Can 18-8 and 304 stainless steel wire insert material be used interchangeably? The short answer is yes, since 304 Stainless Steel belongs to the 18-8 family.

The long answer lies in understanding the slight, yet significant differences between 18-8 and 304 Stainless Steel. At first glance, they are thought to be equivalent due to their nearly identical chemical compositions. Take for instance the concentration of the main elements -Chromium and Nickel-, which offer stainless steel its corrosion resistance (Chromium), and its durability and shine (Nickel), see Table 1.

Although both materials perform comparably in many applications, 304 stainless steel tends to provide enhanced corrosion resistance and durability because of its standardized composition and consistent manufacturing methods.

304 Stainless Steel wire is designated within the Unified Numbering Systems (UNS) that uses the prefix (S) to identify specific stainless steel alloy. For 304 that designation is S30400 and is the default material for helical coil screw thread inserts manufactured in accordance with AS7245 and NASM8846 and certified to NAS1130, NASM21209, NASM122076 Series, and NASM124651 series. 304 Stainless Steel is also default material for metric inserts in accordance with AS7245 and MA1565 and certified to NA0276, MA3279, MA3280, MA3281, MA3329, MA3330 and MA3331.

KATO Fastening Systems manufactures both Tangless and tanged screw thread inserts using several material options including Nitronic 60, Phosphor Bronze and Inconel X750. However, Stainless Steel (most popular) is the only material listed in the above referenced specifications. 304 Stainless Steel has a wide range of uses such as: industrial, automotive, aviation, and aerospace applications, having an operating temperature range between -320°F and 800°F.