Stainless Steel Grades

Chapter 1: What Are Stainless Steel Grades?

Stainless steel grades each consist of carbon, iron, 10.5%-30% chromium, nickel, molybdenum, and other alloying elements. It is a popular metal used in various products, tools, equipment, and structures that serve in many industrial, commercial, and domestic applications.

Corrosion resistance is the most valuable property of stainless steel. Chromium is the alloying element responsible for corrosion resistance. This element reacts with oxygen in air and water and forms a thin, stable chromium oxide film protecting the underlying metal surface. Molybdenum enhances corrosion resistance by protecting the film from pit formation. The protective layer is regenerated after slight abrasions. However, rust can still be formed when the layer is severely damaged after exposure to chlorides, strong cleaning agents, environments with high salinity and high humidity, and after high abrasion.

Aside from corrosion resistance, stainless steels are known for their excellent mechanical properties such as high strength, toughness, ductility, fatigue strength, and wear resistance. Stainless steels can withstand high temperatures, high pressures, and cryogenic environments. They are non-reactive to most chemical substances; hence, they are commonly used in chemical handling equipment and vessels. They also have an aesthetically pleasing, lustrous, and bright surface.

Chapter 2: Categories of Stainless Steel Grades

Stainless steel grades are divided into five main categories:

Austenitic Stainless Steels

Austenitic stainless steel is the most common type of stainless steel. It is named after an English metallurgist named Sir William Chandler Roberts-Austen. It is the most widely used category of stainless steel, which comprises the 200 and 300 series.

Austenitic stainless steels possess a face-centered cubic (FCC) crystal structure by further adding nickel, manganese, and nitrogen. The FCC structure exists at all temperatures. Austenitic stainless steels moderate to high nickel content ranging from 8-12%. Their high manganese and nitrogen contents stabilize the austenitic structure. However, the addition of these elements makes them more expensive. Carbon is present in low concentrations.

Austenitic stainless steels cannot be hardened by heat treatment; hence, they are cold worked to increase their strength and hardness and improve their surface finish. They are non-magnetic and can be slightly magnetic after cold working. They possess high formability and weldability. Since their chromium content is also high (16-30%), austenitic stainless steels possess superior chemical resistance.

Ferritic Stainless Steels

Ferritic stainless steels possess a body-centered cubic (BCC) crystal structure. They have high chromium content ranging from 11% to 27%, but they contain small amounts of nickel. The carbon content of ferritic stainless steel is low (about 0.03%), making it highly ductile and formable. However, like austenitic steels, they cannot be hardened by heat treatment.

Ferritic stainless steels are magnetic. They have high thermal conductivity; hence, they are suitable materials for constructing boilers, heat exchangers, and other applications involving heat transfer. They have a low coefficient of thermal expansion; thus, they are dimensionally stable in a wide range of temperatures. They also have excellent resistance to stress corrosion cracking due to their ferritic structure, which enables them to withstand chlorides, high humidity, and high temperature.

Martensitic Stainless Steels

Martensitic stainless steels possess a body-centered tetragonal crystal structure. They consist of 11.5-18% chromium and 0.1-1.2% carbon. The relatively high strength and brittleness of martensitic stainless steels are attributed to their high carbon content. However, nickel present in martensitic stainless steel is low, which makes them less resistant to corrosion. Martensitic stainless steels are divided into two types based on their carbon content: low carbon martensitic steels (0.05-0.25% carbon) and high carbon martensitic steels (0.61-1.50% carbon). Low carbon martensitic steels provide better corrosion resistance, but high carbon martensitic steels have higher strength and are more brittle.

The hardness and strength of martensitic stainless steels can be increased by heat treatment processes including age hardening, annealing, quenching, and tempering. Martensitic stainless steels are magnetic and impact-resistant. However, they are difficult to weld and form due to their brittleness.

Ferritic and martensitic stainless steels comprise the 400 series.

Duplex Stainless Steels

Duplex stainless steels possess both austenitic and ferritic phases in their microstructures in approximately equal proportions. They are twice as strong as regular austenitic and ferritic stainless steel. Their toughness, ductility, and formability are greater than ferritic steels but never reach the level of austenitic steels. Duplex stainless steels have good resistance to stress corrosion cracking inherited from the ferritic side. Corrosion resistance varies greatly in duplex stainless steels since this property depends on the composition; resistance to pitting and crevice corrosion increases as the content of nickel, molybdenum, and nitrogen are increased. In terms of cost, duplex stainless steels remain a cheaper alternative to austenitic stainless steel.

Precipitation-Hardened Stainless Steels

Precipitation-hardened (PH) stainless steels contain small amounts of copper, aluminum, titanium, and molybdenum. After the stainless-steel elements have been alloyed, the stainless steel is subjected to age hardening treatment in order to precipitate these elements as hard intermetallic elements. The precipitate phase impedes the movement of dislocations, the defects in the crystal lattice structure, and imparts excellent strength and hardness to stainless steels. PH stainless steels have corrosion resistance comparable to austenitic stainless steels.

PH stainless steels are categorized into three types: martensitic, austenitic, and semi-austenitic PH stainless steels. Austenitic PH steels retain their crystal structure at all temperatures. Semi-austenitic PH steels remain austenitic after solution treatment and quenching; the austenitic structure is converted into martensitic after cryogenic treatment or cold working.

Leading Manufacturers and Suppliers

Chapter 3: Stainless-Steel Grades

There are over 150 stainless steel grades, but only around 15 of them are commonly used. The most popular stainless steel grading system was developed by the Society of Automotive Engineers (SAE). Other grading systems were developed, like the Universal Numbering System (UNS) for Metals and Alloys, and they can vary in different regions.

The stainless-steel grades and their properties are the following:

Austenitic Chromium-Nickel-Manganese Alloys (Grade 200 series)

Grade 201 Stainless Steel

Grade 201 stainless steel is an austenitic stainless steel containing 16-18% chromium and 3.5-5.5% nickel. It is a substitute for grade 304 stainless steel and high nickel alloys. Due to its lower nickel content, it offers below-average protection from corrosion. However, it is cheaper than other stainless steel, and the concentration of manganese and nitrogen can be increased to improve its yield strength. The versatility of grade 201 is owed to its good formability and weldability.

Grade 202 Stainless Steel

Grade 202 stainless steel is an austenitic stainless steel containing 17-19% chromium, 4-6% nickel, and 7.5-10% manganese. It is one of the stainless-steel grades widely used for precipitation hardening and has good corrosion resistance, high hardness, toughness (even at lower temperatures), strength, and weldability. It almost has similar properties with grade 302, but grade 202 has lower yield strength. Grade 202 can be machined in an annealed condition. Like grade 201, grade 202 is also cost-efficient.

Austenitic Chromium-Nickel Alloys (Grade 300 series)

Grade 301 Stainless Steel

Grade 301 stainless steel is austenitic stainless steel. It offers the same corrosion resistance with grade 304 in mildly corrosive environments at ambient temperatures; however, the corrosion resistance of grade 301 is lower in extremely corrosive and high-temperature environments due to its lower chromium content (16-18%).

Grade 301 stainless steel possesses high strength and is available in annealed and cold-worked conditions. The annealed variation of this grade offers high formability, while the cold worked variation has higher strength. 301 stainless steel becomes magnetic when cold worked. It is suitable for welding. However, welded grade 301 parts need annealing to dissolve the precipitated chromium carbide induced by welding and prevent the intergranular attack.

Grade 301L stainless steel is a variant of grade 301 that has improved ductility and weldability. It does not need to be annealed for maximum corrosion resistance. Another variant is the grade 301LN stainless steel, which contains higher nitrogen and has a higher work hardening rate. Annealing is not necessary for these variants.

Grade 302 Stainless Steel

Grade 302 stainless steel is an austenitic stainless steel containing about 18% chromium and 8% nickel. Its chemical composition is almost the same as the grade 304, except for slightly higher carbon content. Grade 302 has high toughness, tensile strength, yield strength, and corrosion resistance. Grade 302 stainless steel is processed at low speeds and high feed volumes to overcome their work hardening tendencies. Due to gummy chip formation, it is advised to use chip breakers on all tooling. The recommended welding methods for grade 302 are resistance and shielded fusion welding. Post weld annealing must be performed.

Grade 304 Stainless Steel

Grade 304 stainless steel is the most popular austenitic stainless steel. It contains 18% chromium and 8% nickel: thus, deriving its old name 18/8. Grade 304 has excellent chemical, oxidation, and corrosion resistance in a wide range of temperatures. However, it is susceptible to pitting corrosion and stress corrosion cracking when exposed to chlorides. Low and high carbon content variants of grade 304 are available, which are the grade 304L and grade 304H, respectively.

Aside from excellent corrosion resistance, grade 304 stainless steels have high ductility. Hence, they can be easily formed and machined into varieties of products. They can be severely deep-drawn. Grade 304 has higher formability than grade 316. However, they require annealing after cold working to minimize work hardening.

Grade 305 Stainless Steel

Grade 305 stainless steel is austenitic stainless steel that contains 18% chromium, a minimum of 10% nickel, and a high amount of carbon. It has good chemical and corrosion resistance and high strength. It has a low rate of work hardening due to its elevated nickel content. The low rate of work hardening makes grade 305 suitable for deep drawing applications. Grade 305 can be welded with resistance and fusion methods; however, oxyacetylene welding is not recommended.

Grade 309 Stainless Steel

Grade 309 stainless steel is an austenitic stainless steel containing a minimum of 22% chromium, 12% nickel, and a low amount of carbon. It possesses excellent corrosion and oxidation resistance, high tensile and creep strengths maintained at high temperatures. It can withstand saline environments. Grade 309 stainless steels can be rolled, formed, stamped, and deep drawn readily; annealing is required after cold working to prevent work hardening and maintain its ductility.

Grade 316 Stainless Steel

Grade 316 stainless steel is the most popular and widely used stainless steel grade next to grade 304. It is an austenitic stainless-steel containing elevated amounts of molybdenum and high amounts of silicon, manganese, carbon, chromium, and nickel. High molybdenum concentration makes grade 316 more resistant to pitting and crevice corrosion than grade 304 in saline environments. Grade 316 has good forming and welding characteristics; annealing is usually not required after welding thin sections.

Grade 316 has two variants: grade 316L and grade 316H stainless steel. Grade 316L has lower carbon content and is insusceptible to chromium carbide precipitation. Hence, grade 316L is preferred when a project requires much heavy welding. Meanwhile, Grade 316H has higher carbon content; therefore, it has higher tensile and yield strength and is more suitable in high-temperature applications.

Grade 321 Stainless Steel

Grade 321 stainless steel is a titanium-stabilized austenitic stainless steel with good corrosion resistance. It has excellent resistance to chromium carbide precipitation when exposed to high temperatures. It also has higher creep and stress rupture properties than grade 304. All these properties are maintained in high temperatures.

Grade 321H is a modification of grade 321. It has an enhanced creep resistance, and its higher carbon content increases its strength at higher temperatures.

Grade 347 Stainless Steel

Grade 347 stainless steel is a niobium-stabilized austenitic stainless steel. Like grade 321, grade 347 is also insusceptible to chromium carbide precipitation and has excellent intergranular corrosion resistance. It has higher creep and stress rupture properties than grade 304. It has good corrosion resistance and offers oxidation resistance slightly better than grade 321.

Ferritic and Martensitic Chromium Alloys (Grade 400 series)

Grade 409 Stainless Steel

Grade 409 stainless steel is ferritic stainless steel stabilized by the presence of titanium and/or niobium. It has good mechanical properties and corrosion resistance that are maintained at high temperatures. It has good formability and welding characteristics. It can be welded by various methods such as arc, resistance spot, and seam welding. However, grade 409 welding requires preheating to 150-2600C and post-weld annealing to improve ductility. It is not suitable for aesthetic applications as it tends to form light surface rusting.

Grade 410 Stainless Steel

Grade 410 stainless steel is a heat-treatable, general-purpose martensitic stainless steel containing 11.5% chromium. Processes such as hardening, tempering, and polishing are performed in grade 410 stainless steels to elevate wear resistance, corrosion resistance, and overall mechanical properties. It is compatible with water, air, hot gases, food products, and most chemicals such as mild acids, nitric acid, concentrated sulfuric acid, dilute acetic acid, and naphtha. However, grade 410 is only suitable for mildly to moderately corrosive environments due to their lower nickel content.

Grade 410 can be welded by most conventional welding methods. To mitigate the risk of cracking, it should be preheated between 150° and 260°. Post welding annealing should also be performed. This grade maintains its ease of machinability after tempering and annealing processes. Grade 410 steels are used in refinery equipment, turbines, pumps, valves, and as a material for machine elements such as bolts, screws, nuts, and bushings.

Grade 420 Stainless Steels

Grade 420 stainless steel is martensitic stainless steel with high carbon content of 0.15 to 0.45% and a minimum chromium content of 12%. It is a higher form of grade 410. Its strength significantly increases by about 1000 MPa when hardened and stress relieved. Its corrosion resistance is lower than austenitic and ferritic stainless steel, but it is enough to withstand mild acids, alkali, freshwater, normal atmospheric conditions, and food products. It has good ductility in its annealed state but has poor corrosion resistance; hence, it is utilized in the fully hardened, surface grounded, or polished condition.

Grade 420 can be machined easily, but its machinability decreases with increasing hardness. Grade 420 steels with hardness greater than 30 HRC are difficult to machine. Grade 420 is widely used in making cutting tools (e.g., knives, dies), cutlery, needles, surgical tools, and bushings.

• Grade 420HC

  Stainless steel grade 420HC has higher carbon content than grade 420 but is considered to be a softer steel when compared to other steel types and is rated as a mid range steel. Its higher carbon content gives 420HC higher hardness. Grade 420HC is ideal for the manufacture of cutting tools since it has good edge retention and sharpens easily. The significance of edge retention refers to the ability to maintain a sharp edge. Grade 420HC is more expensive than grade 420 and has lower corrosion resistance.

  Knives made using 420HC are popular with hunters and fishermen since 420HC holds up well in hostile weather conditions. Since it is less expensive than steel, it is used to make lower cost knives that are sold by large retailers. Stainless steel grade 420HC sharpens easily but does not hold its edge like a steel blade, which requires that it be sharpened frequently.

• Grade 420J2

  Stainless steel grade 420J2 is inexpensive and is corrosion resistant in mild atmospheres such as domestic and industrial environments. Additionally, grade 420J2 is resistant to dilute nitric acid, carbonic acid, ammonia, crude oil, detergent solutions, vinegar, food acids, several petroleum products, and steam.

  What differentiates stainless steel grade 420J2 from other steels is its strength and impact resistance in conditions of hardening and tempering. It can be turned, drilled, and bent. Grade 420J2 can be annealed at 730° C up to 790° C or 1346° F up to 1451° F.

  Stainless steel grade 420J2 is used to manufacture surgical instruments, daggers, swords, budget knives, diving knives, domestic scissors, and hair cutting scissors.

Grade 430 Stainless Steel

Grade 430 stainless steel is ferritic stainless steel primarily composed of chromium and iron; the concentrations of carbon, nickel, and other alloying elements are very low, making grade 430 stainless steels less expensive. It has good heat and corrosion resistance which can handle organic acids and nitric acids. Being ferritic stainless steel, it has excellent stress corrosion cracking resistance. Grade 430 has good machinability and formability and a low work hardening rate. However, it has a low ductility rate and is prone to galling.

Grade 434 Stainless Steel

Grade 434 stainless steel is the most common non-hardenable ferritic stainless steel, which contains high molybdenum to increase its corrosion and heat resistance. Its performance is close to that of grade 430.

As a very widely used ferritic stainless steel, grade 434 is capable of withstanding temperatures of up to 1500°F. Due to its exceptional resistance to high temperatures, it cannot be hardened by heat treatment and is cold formed like low carbon steel. The main use of stainless steel grade 434 is as auto trim.

Grade 440 Stainless Steel

Grade 440C stainless steels are high carbon steels with high hardness, wear resistance and strength after heat treatment. The high hardness of grade 440 makes it suitable for applications such as valve components and ball bearings. Grades 440A and 440B have similar properties as 440C with lower percentages of carbon in grade 440A.

All grades of 440 stainless steel are commonly used with grade 440C being more readily available. Grade 440F is a machining type of grade 440 stainless steel with a carbon content that is similar to grade 440C.

Grade 440 stainless steels should not be used in high temperature applications due to the risk of being over tempered. All sub-grades of grade 440 have similar properties with grade 440C having similar corrosion resistance as stainless steel grade 304.

Chapter 4: Forms of Stainless Steel

As with any form of metal alloy, stainless steel is shaped and formed for easy delivery for manufacturing and production processing. Stainless steel suppliers and manufacturers produce raw stainless steel in a shape that fits the product for which it will be used. Coils are used in a wide variety of ways including kitchen appliances, automotive parts, and medical instruments while stainless steel bars are used to produce cutlery, plumbing, and construction materials.

Coils

Stainless steel coils are flat strips that are rolled from stainless steel sheets and come in thicknesses of 0.02 mm up to 6 mm (0.0008 inch up to 0.23 inch). The initial form of stainless steel is slabs that are put through a Z mill, a series of rollers, to produce stainless steel coils. The Z mill process produces wide coils that are referred to as mill edge coils.

The wide coils are further processed using slitting that slits the coils into strands that become a batch of coils, which are referred to as strip coils, slit coils, banding, or strips. How the coils are wound determines what type of coil they are with the different types being pancake, ribbon, or bobbin. Typically, coils are wound on top of a strip that has even edges, which is limited in the size of its outer diameter (OD) to enable safe handling of the coil.

There are an endless number of uses for stainless steel coils such as the auto industry that uses stainless steel for the structure of automobiles. A very common use for stainless steel coils is in the manufacture of equipment for food production including counter tops and processing machines. Aside from these two predominant uses, stainless steel coils are used in the aerospace industry, defense, pipelines and fittings, and construction.

Bars

Stainless steel bars come in several forms and are referred to as rods, rounds, and round bars. They are made of various grades of stainless steel with grades 304 and 316 being the most common. Stainless steel bars can be flat, round, hexagonal, octagon, or square depending on the company that is processing them. Although stainless steel bars can be used in the shape that they are produced, in the majority of cases, they are melted down to be reworked into channels, tubing, or extruded angles.

Of the various forms of stainless steel, bars are the most economical since they have greater volume than other forms. Additionally, bars are easier to ship and process predictably. The different shapes of stainless steel bars is an indication of the application for which they will be used and how they will be processed.

The first step in manufacturing stainless steel includes the melting of the raw materials, which takes eight to twelve hours. The molten stainless steel is cast into bars, which are hot rolled into different shapes. Once the bars are formed, they are annealed by being heated and cooled through quenching or air hardening. When the stainless steel is completely cooled, it is descaled or pickled to remove oxide film, the result of the hot forming process.

Foil

Stainless steel foil is thin strips of stainless steel with a thickness of 0.2 mm (0.008 inch) and width of 300 mm (12 inches) or less. It has all of the properties and characteristics of stainless steel and is used in the production of heat exchangers, capacitors, and fuel cells. One of its predominant uses is in the manufacture of sensitive medical instruments and food processing equipment.

Several grades of stainless steel are used in the fabricating of stainless steel foil including grades 301, 304, 316, 409, 430, and duplex 2205. As with all stainless steel products, stainless steel foil comes in several forms, which include full hard, half hard, and quarter hard.

Of the grades of stainless steel foil, grade 304 is used the most for the production of foil due to its adaptability, versatility, and availability. It provides high quality performance at a relatively low price. The qualities of grade 304 that makes it ideal for the production of stainless steel foil are its low thermal and electrical conductivity and being non-magnetic. Additionally, aside from its high corrosion resistance, grade 304 is easily formable and is capable of being formed and shaped into any configuration.

Stainless steel foil is thin, flexible, layered, and can be wrapped around equipment, objects and other items as a layer of protection. It is readily available and can be purchased directly from the manufacturer or online. The popularity of stainless steel foil is due to its strength and longevity.

Plate

Stainless steel plates come in different sizes and thicknesses. They are made from slabs that are 4 inches thick or thicker. To reach the proper dimensions for stainless steel plates, the slabs are cold or hot rolled where they are fed through a set of rollers that reduce their thickness. Cold rolling is used in conditions where the metal needs increased strength or a very precise thickness. All of the various grades of stainless steel can be formed into stainless steel plates with grades 304 and 316 being the most common.

The distinction between stainless steel plate and stainless steel sheet is their thickness. If the thickness of the stainless steel is 6 mm (0.25 inch) or greater, then it is regarded as being stainless steel plate. A further difference between the two is their means of measurement with stainless steel plate having its thickness measured in inches while stainless steel sheet is measured in gauges. As is common with all forms of stainless steel, both forms are measured in millimeters.

Stainless steel plate is a popular material for the manufacture of a wide assortment of products due to its resistance to abrasion, ease of cleaning, and pleasing appearance. How stainless steel plate is used is dependent on its grade with grades 304 and 316 being the most common with grade 304 being divided into 304, 304H, and 304L.

Rod

Stainless steel rods come in different shapes and are used in support structures, appliances, and machinery. The sizes of stainless steel rods vary according to their metal content and intended use. They range in diameter from 1.5 mm to 152.4 mm (0.625 in to 6 in). In construction, they are used as reinforcement for masonry and fence posts.

A unique characteristic of stainless steel rods is their alloy content, which varies from stainless steel bars. Rods have a low carbon content and high manganese content that gives them better wear resistance. High carbon content makes stainless steel harder and brittle, which makes it prone to cracking. The increased manganese content in stainless steel rods makes them more durable.

Stainless steel rods are extruded from a stainless steel billet. The process for extruding rods begins by heating the billet such that it is malleable but not molten. The heated metal is forced by a hydraulic process through a die made of hardened steel that has the final shape of the rod. As they exit the die, the extruded rods are sent to the drawing area where they are pointed, drawn, straightened or cold rolled.

The shapes of stainless steel rods include:

• Square
• Hollow
• Solid
• Round
• Hexagonal
• Flat
• Rectangular
• Octagonal

Sheets

Stainless steel sheets are thin, flat sheets of stainless steel that are less than 6 mm (0.25 in) thick, which is measured in inches or mm. They are made from slabs of stainless steel that has been passed through a Z mill that compresses the slabs to the correct thickness for the sheets. The normal thickness of stainless steel slabs is four or more inches, which is the reason they have to be compressed by the multiple rollers of a Z mill.

The rolling process can be hot or cold. In the hot rolling process, stainless steel slabs are heated above their recrystallization temperature. It is a faster process than cold rolling and can decrease the thickness of the metal to 0.28 mm (0.011 in). The cold rolling process involves passing cold slabs through the rollers of a Z mill multiple times to reach precise thicknesses and dimensions.

Stainless steel plates and sheets are produced using the same process. They are differentiated by their thickness with sheets being less than 6 mm (0.25 in) while plates have a thickness that is greater than 6 mm (0.25 in). Aside from their mm or inch measurements, stainless steel sheets are measured in gauges that are different from the gauges used to measure other sheet metals.

Strips

Stainless steel strips are an extension of stainless steel sheets that are thin, long, and narrow strips. They are also known as stainless steel coils and come in various widths. Although the width of stainless steel strips is standard, they are available in lengths to meet the needs of an application or the preferences of customers. The popularity of stainless steel strips is due to their exceptional strength and smooth even lustrous finish.

The two processes used to produce stainless steel strips are cold rolling and hot rolling. The thickness of cold rolled stainless steel strips varies between 0.1 mm up to 3 mm (0.004 in up to 0.12 in) with widths of 100 mm up to 2000 mm (4 in up to 79 in). Cold rolled stainless steel strips have smooth flat surfaces with extremely accurate measurements, good mechanical properties, and can be processed into coated plates.

Hot rolled stainless steel comes in thicknesses of 1.8 mm up to 6 mm (0.07 in up to 0.23 in) with widths of 50 mm up to 1200 mm (2 in up to 47 in). Stainless steel strips that have been hot rolled have low hardness, are easy to process, and can be easily stretched. Unlike cold rolled stainless steel strips, hot rolled strips have dark rough surfaces due to the scale that forms on the strips during the heating process.

Stainless steel strips are made from series 200, 300, and 400 stainless steels and can be divided into austenitic, ferritic, martensitic, duplex, PH, and super austenitic grades. The various grades of stainless steel strips are designed to meet the needs of a wide range of applications from aerospace and automobile manufacturing to home appliances and computers.

Wire

Stainless steel wire has many uses that include spring wire, cutting wire, cold heating wire, and roping wire. Each type is used in a different way and has properties to meet the needs of an application. The gauges of stainless steel wire include 14 AWG up to 44 AWG with other gauges manufactured to meet the requirements of customers. The various gauges are further differentiated by the grade of stainless used to manufacture them.

Spring wire is the most common form of stainless steel wire. It is made from 300 series and 400 series stainless steel with the selection of grade determined by the required properties, spring design, and fabrication method. The outstanding characteristic of stainless steel spring wire is its ability to withstand varying levels of heat.

Cutting stainless steel wire is known for its rigidity and surface hardness. It has excellent machinability and surface hardness. Stainless steel cutting wire received its name from its ability to retain its roundness when it is cut. It is exceptionally machinable with consistent dimensional tolerances and can be rapidly cut, which saves the life of tools.

Cold heating stainless steel wire is used in the manufacture of bolts, nuts, nails, and screws. It is produced to the strictest industrial standards to ensure the quality of connectors. The main characteristics of cold heating stainless steel wire are its tensile strength and microstructure that remains stable over time.

Roping stainless steel wire is a unique form of wire that is used to assemble wire rope. It comes in several sizes and a wide range of diameters. Unlike other forms of stainless steel wire, roping stainless steel wire is used in unison with other wires that are the same or different. The critical factors for roping stainless steel wire are its diameter, which influences the diameter of the wire rope, and its tensile strength. Additionally, roping stainless steel wire has to be exceptionally flexible to work in unison with other wires to which it is attached.

Chapter 5: Application of Stainless-Steel Grades

Due to its excellent mechanical properties and corrosion resistance, stainless steel can be found in a variety of products, equipment, and structures. The applications of the stainless-steel grades include but are not limited to the following:

Grade 201 Stainless Steel Applications

Grade 201 stainless steel is used in structural members, decorative materials, household items, cooking utensils, windows, doors, automotive parts, railroad cars, and trailers.

Grade 202 Stainless Steel Applications

Grade 202 stainless steel is formed into sheets, coils, and plates in order to manufacture household items, kitchenwares, structural members, automotive trim, hose clamps, and railway cars.

Grade 301 Stainless Steel Applications

Grades 301 and grade 301LN stainless steels are used in aircraft components, structural components for railcar, automobiles, trucks, trailers, appliances, cooking utensils, kitchenwares, wiper blade clips and holders, screen frames, and curtain walls.

Grade 301L stainless steels are used in pressure vessels, door and drainage parts, utensils and appliances parts, and structural components for railcars.

Grade 302 Stainless Steel Applications

Grade 302 stainless steels are commonly used in food handling equipment, cooking utensils, kitchenware, pressure vessels, and medical tools. They are widely sold in spring (conical compression springs), screen, cable, and wire forms.

Grade 304 Stainless Steel Applications

Grade 304 stainless steels are used to manufacture deep-drawn sinks, pans, pots, and troughs. Grade 304 is also used in mechanical fasteners (nuts, bolts, and screws), industrial plant equipment (pressure vessels, storage vessels, tubing), kitchenware, cutlery, cooking utensils, decorative pieces, and architectural paneling.

Grade 305 Stainless Steel Applications

Grade 305 stainless steels are formed into deep drawn parts, cups, pans, bowls, eyelets, rivets, and screws.

Grade 309 Stainless Steel Applications

Grade 309 stainless steels are used to construct boilers, furnaces, ovens, heat exchangers, kilns, aircraft engines, and automotive exhaust parts.

Grade 316 Stainless Steel Applications

Grade 316 stainless steels are commonly used in constructing chemical storage tanks, heat exchangers, reactors, furnaces, and other process equipment. Grade 316 is preferred in marine environments and in the refinery industry. It is also used in architectural panels and railings.

Grade 321 and 347 Stainless Steel Applications

Grade 321 and grade 347 stainless steels are used in aircraft and aerospace components, expansion joints, bellows, furnace parts, heat exchangers, heating element tubing, and chemical process equipment.

Grade 409 Stainless Steel Applications

Grade 409 stainless steels are originally developed for automotive exhaust systems, but their application has expanded to catalytic converters, mufflers, fuel filters, heat exchangers, and agricultural machinery.

Grade 410 Stainless Steel Applications

Grade 410 stainless steels are used to manufacture cutlery, knives, flatware, cutting tools, bolts, bushings, and nuts. They are used to construct petroleum fractionating equipment, gas turbines, pumps, shafts, and valves.

Grade 420 Stainless Steel Applications

Grade 420 stainless steels are commonly found in cutlery, surgical and dental instruments, scissors, blades, and other cutting tools. Grade 420HC and grade 420J2 are used in economical knives and cutting tools.

Grade 430 Stainless Steel Applications

Grade 430 stainless steels are used in kitchen utensils, sinks, dishwasher linings, pipes, tubes, and automotive trim.

Grade 434 Stainless Steel Applications

Grade 434 stainless steels are used in automotive trim, furnace chambers, range hoods, gas burners, steam iron bases and flatware, and chemical process equipment.

Grade 440 Stainless Steel Applications

Grade 440 stainless steels are used in valves, valve seats, ball bearings, and cutlery.

Stainless Steel Screws

Stainless steel screws have superior mechanical properties and corrosion resistance, making them a suitable fastener for a variety of environments.

Self-Drilling Screws

Self-drilling screws are screws that can tap its hole as it is drilled into the material. They require a pre-drilled or pre-punched hole. They are used in softer and thinner materials.

Self-Tapping Screws

Self-tapping screws are screws that can drill their own holes in the material. They can be used in wood, plastic, and metal substrates.

Thread Cutting Screws

Thread cutting screws are screws that drill threads in predrilled holes on a material.

Chapter 6: Top Stainless Steel Manufacturers

Cleveland-Cliffs

Cleveland-Cliffs is a world leader in the production of stainless for the auto industry, construction, and power companies. The company has been operating for over 150 years and is the largest flat rolled steel manufacturer in North America. One of its goals, over the years, has been to drastically lower emissions from steel production, which has been successfully lowering over the last ten years. Cleveland-Cliffs manufactures over 50 grades of stainless steel.

Source 21, Inc.

Source 21 manufactures stainless steel coils and strips and custom processes any grade of stainless steel. The company uses rolling for reducing the thickness of stainless steel to reach the appropriate gauge and thickness to meet customer needs. Rolling produces stainless steel with a consistent gauge to prevent weakness or deformation. Using Z milling, Source 21 gradually reduces the thickness of stainless steel to produce high quality coils and strips.

North American Stainless (NAS)

NAS is one of the largest stainless steel producers of high quality stainless steel in the United States. The company produces cold and hot rolled coil, sheets, and plate in a variety of stainless steel grades for several industries. The central focus of their production is on grades 201, 301, 304, 309, 310, 316, and 321, which are available in the basic forms of stainless steel. NAS is one of the largest recyclers of steel with the goal of reducing waste and reusing metals.

Metalmen Sales, Inc.

Metalmen Sales is an on demand supplier of stainless steel with 100 years of industry experience. The company’s metal working processes include rolling, slitting, tempering, shearing, and heat treating to produce high quality stainless steel. Metalmen has a huge inventory of stainless steel foil, rods, bars, strips, coils, sheets, and plates in a wide selection of grades, including PH stainless steel.

Cada Stainless & Alloys

Cada is a distributor of basic stainless steel grades with most grades having been annealed or tempered. The company has available stainless steel with a rough gray finish, dull finish, bright silvery finish, and mirror finish. Cada provides stainless steel with a PVC coating to prevent scratching or other damage during shipping. The company has been in business for 35 years and provides stainless to the auto industry, oil and gas production, appliance industry, and chemical processing.

Conclusion

• Stainless steel is a type of steel containing a minimum of 10.5% chromium, nickel, molybdenum, and other alloying elements. It has excellent mechanical properties and corrosion resistance and can withstand high temperatures, cryogenic environments, and high pressures.
• The categories of stainless steel are austenitic, ferritic, martensitic, duplex, and precipitation-hardened stainless steel.
• There are over 150 stainless steel grades, but only around 15 of them are commonly used. The SAE developed the most widely adapted stainless steel grading system.
• Stainless steel is a popular metal used in a variety of products, tools, equipment, and structures that serve in many industrial, commercial, and domestic applications.
• Stainless steel screws offer excellent corrosion resistance. The most common types of stainless-steel screws are self-drilling, self-tapping, and thread-cutting screws.

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