The Fabrication of Products Using Stainless Steel
How is stainless steel fabricated?
Stainless steel can be fabricated using any of the traditional forming and shaping methods. Austenitic stainless steel can be rolled, spun, deep drawn, cold forged, hot forged, or stippled using force and stress. Though stainless steel has a great deal of strength and a high hardening rate, it is very ductile, which enables it to be cold formed.
Deciding on the type of stainless steel for a project requires an understanding of the many grades, which are divided into four families – austenitic, ferritic, martensitic, and duplex. The largest of the four groups is austenitic made from combining steel, nickel or manganese, and nitrogen. It is the main choice for producing a wide variety of products. Ferritic stainless steel contains carbon steel and chromium. Martensitic stainless steel comes in four types with a combination of iron, chromium, and carbon. How the materials are combined and depending on the addition of other alloys determines the type of martensitic stainless steel. Duplex stainless steel is a combination of austenite and ferrite in various percentages and ratios.
Grades of stainless steel are numbered. The type of numbering system depends on who is doing the grading since they vary between Great Britain, the International Organization of Standardization, Japan, Europe, Germany, and China. Regardless of the classification system, every organization has the same basic requirements and standards that define what stainless steel is.
The method of fabrication used to shape stainless steel depends on the grade and its type of alloys. Each grade has different qualities that makes it easier or more difficult to shape. They all have the one commonality of corrosion resistance and endurance though some may have lesser versions of these qualities.
Types of Stainless Steel for Fabricating
Different types and grades of stainless steel have varying uses. When choosing stainless steel for a project, careful consideration has to be given the use of the product, method of forming, and equipment to be used. A miscalculation of any of these factors can lead to an unfortunate outcome.
There are five basic types of stainless steel that manufacturers use to create industrial and household products. What has to be kept in mind is the varying grades of stainless steel beyond these five types.
Ferritic stainless steel has a chromium base with a low amount of carbon. It is not ideal for conditions where welding is needed but is perfect for marine environments with its high corrosion resistance.
Austenitic stainless steel is the most commonly used. It can be welded, formed, shaped, and reconfigured for multiple purposes. Austenitic stainless steel is formed by combining nickel, manganese, and nitrogen. The austenitic form of stainless steel can be cold worked, which improves its hardness, strength, and stress resistance. It can also be heated to be shaped but returns to its original strength when cooled. Austenitic stainless steel is classified in the 200 and 300 series of stainless steel.
Duplex stainless steel has a combination of the characteristics of austenitic and ferritic offering the benefits of both, which gives its name using 50% of each alloy. It has twice the strength of other stainless steels and is able to withstand extreme pressure conditions. The low cost of duplex stainless steel makes it attractive though it is the least used of the varieties of stainless steel.
Martensitic stainless steel is a composition of iron, chromium, and carbon, a 410 grade of stainless steel. It has high strength, hardness, and wear resistance but is poor for welding and has low plasticity. Martensitic stainless steel is used for cutting tools and dental and surgical instruments.
Precipitation hardening (PH) stainless steel is corrosion resistant and can be heated treated to reach tensile strengths of 850MPa and higher, up to four times harder than austenitic stainless steel. It is an alloy produced by combining copper, molybdenum, aluminum, and titanium. There are three types of PH stainless steel - low carbon martensitic, semi-austenitic, and austenitic.
How Stainless Steel Products are Used
Modern appliances and industrial products are made of stainless steel due to its ability to adapt to extreme temperatures, corrosion and rust resistance, and superior strength. Consumers have become rather particular about the types of products they require. One of their main stipulations is that products necessitate limited care and can endure all forms of use. The popularity of stainless steel rests in its ability to meet the exacting requirements of consumers, especially its ability to maintain its appearance in stressful conditions.
Stainless steel is non-porous and scratch resistant. Its sturdiness makes it perfect for environments that require sanitary and antiseptically clean conditions such as large kitchens and medical facilities. Counter tops, cookware, and utensils in the food processing industries are made from stainless steel to meet the exacting requirements of food boards and health inspectors. In the medical field, infection can easily be passed by unclean hands and instruments. Since stainless steel can withstand the various disinfecting treatments that health professionals demand, it is widely used in the production of surgical instruments and tools.
One of the more popular uses for stainless steel is in the manufacture of storage tanks for the obvious reasons of its resistance to corrosion and rust. Agriculture, fire protection, fuel transport and storage, and other industries that require strong and sturdy storage tanks depend on stainless steel to store their products in huge amounts. This is especially true for the chemical industries that have to have metal tanks that do not interact with the stored substance.
The uses of stainless steel are endless due to its tensile strength, resistance to corrosion and rust as well as its sleek clean appearance. It is used to produce products from subway trains and airplanes to garden implements and tools. Each year, new and innovative designs are introduced to make use of its special qualities.
Making the Decision to Use Stainless Steel for Fabricating a Product
With the wide variety of grades and families of stainless steel, selecting the right grade for a project can be difficult. There are important considerations when designing a stainless steel product. Since stainless is known for its strength and corrosion resistance, it is natural to assume that all stainless steel has these features. Each grade and type of stainless steel does have these characteristics to varying degrees. The grade and type determines the percentage and amount of corrosion resistance, strength, and durability of a particular type. Before making the decision to produce a product using stainless steel, it is wise to study the properties of each type and grade.
The appearance and strength of stainless steel has made it a common part of construction projects. It can be seen as exterior ornamentation such as railings, siding, and fixtures as well as in interior forms like countertops and backsplashes. Its main attractiveness as a construction material is its low maintenance.
Since the 1930’s, stainless steel has played a major part in the production of automobiles. Initially, it was used for exhaust systems, trim, and other non-structural purposes. With the advent of increased emissions standards, stainless steel has become an important component in the structure and design of automobiles.
Stainless steel has had a significant impact on the medical instrument industry due to its ability to be easily sterilized and its corrosion resistance. Aside from surgical instruments, implants, such as hip joints, are made from stainless steel. Pins and plates used to repair broken bones depend on stainless steel.
High carbon grades from 304 to 347 are the most popular and widely used in a variety of industries from the chemical processing of paper to the production of foods and beverages. The 400 series is less corrosion resistant and has a lower cost than the 300 series. It is usually used for surface finishes for its appearance.
Stainless steel, in its many forms, has become a necessary part of product production. Since its introduction over a hundred years ago, producers and manufactures have come to rely on its indestructible qualities for the creation of many of the items we depend on. Though there have been other metals developed in the last thirty years, it is very likely there will be more forms of stainless steel in the future.