What Is Austenitic Stainless Steel?

The most commonly seen type of this metal, austenitic stainless steel is also called 18-8 or casually referred to as the 300 series. These designations come from the composition of the metal, which is made up of 18 percent chromium and 8 percent nickel. 

This group has a higher resistance to corrosion than other steels do, such as martensitic or ferritic steels. And even though austenitic stainless steel cannot be heat treated, there are methods of cold working that will improve the strength. Age hardening processes can also help. An excellent choice for projects that are exposed to very low temperatures, 18-8 stainless steel also works well in high heat and is non-magnetic. 

Fasteners Made From Stainless Steel   

                                                                                              

Around 80 percent of the stainless steel fasteners on the market are made from 18-8 grade. There are a few highly recognized and commonly seen grades including:

• ·        Type 305 (Chromium and Nickel alloys) – This alloy is very dependable due to a high nickel content that allows for easier forming and cold heading.

• ·        Type 384 (Chromium, Nickel and Carbon alloys) – Especially developed for cold heading, this type has a high nickel content (between 17 and 19 percent) that increases the cost of raw materials considerably.

• ·        Type 303 & 303Se (Chromium and Nickel alloys) – This type is good for hot forging, although should be avoided when cold heading processes are required. Used for large nuts that will be machined heavily.

• ·        Type XM7 (Chromium, Nickel and Copper alloys) – Modified from type 302, this type is excellent for cold heading and costs less than the popular 305 and 384 varieties.

• ·        Type 316 (Chromium, Nickel, Molybdenum and Carbon alloys) – The addition of molybdenum makes this type resistant to surface pitting. It also has a higher tensile strength in extreme temperatures than other austentitic types.

There are others on the market and the development of stainless steel continues. With more applications requiring varied specifications, the drive to create better, stronger, more dependable metal fasteners just keeps growing. Austentitic stainless steel is widely used today and that is not likely to change any time soon. This grade delivers superior corrosion resistance, is non-magnetic and holds up in a variety of extreme temperatures.