Austenitic stainless steel

Commonly used trademarks are 302, 303, 304, 305 four trademarks, the so-called "18-8" type austenitic stainless steel four trademarks. Whether it is corrosion resistance, or its mechanical functions are similar. The starting point for selection is the production process method of the fastener, and the method depends on the standard and shape of the fastener, and also depends on the quantity produced.

Type 302 is used to select machined screws and self-tapping bolts.

Type 303 is to improve the cutting function. A small amount of sulfur is added to the type 303 stainless steel, which is used to select bars for processing nuts.

Type 304 is suitable for the use of hot forging process to process fasteners, such as longer standard bolts and large diameter bolts, which may be beyond the planning of cold forging process.

Type 305 is suitable for processing fasteners with cold heading technology, such as cold-formed nuts and hexagonal bolts.

Type 309 and Type 310 have higher Cr content and Ni content than 18-8 type stainless steel, which are suitable for fasteners that operate at high temperatures.

Types 316 and 317, they both contain alloying element Mo, so their high temperature resistance and corrosion resistance are higher than 18-8 type stainless steel.

Types 321 and 347, 321 type contains relatively stable alloying element Ti, 347 type contains Nb, thereby improving the material's anti-intergranular corrosion function. It is suitable for fasteners that are not annealed after welding or are in service at 420~1013C.