410 type and 416 type can be strengthened by heat treatment, the hardness is 35～45HRC, the machining performance is good, it is used for general purpose heat-resistant and corrosion-resistant stainless steel bolts. Type 416 has a slightly higher sulfur content and is a free-cutting stainless steel.

　　 420 type, sulfur content? R0.15%, improved mechanical properties, can be strengthened by heat treatment, the maximum hardness value is 53 ~ 58HRC, used for stainless steel bolts that require higher strength.

　　 precipitation hardening stainless steel

　　17-4PH, PH15-7Mo, they can obtain higher strength than the usual 18-8 type stainless steel, so they are used for high-strength, corrosion-resistant stainless steel bolts.

　　 A-286, a non-standard stainless steel, has higher corrosion resistance than the commonly used 18-8 type stainless steel, and still has good mechanical properties when the temperature increases. Used as high-strength, heat-resistant, corrosion-resistant stainless steel bolts, and can be used at 650-700°C.

　　Austenitic stainless steel

　　The commonly used grades are 302, 303, 304, and 305, which are the so-called "18-8" austenitic stainless steels. Both the corrosion resistance and the mechanical properties are similar. The starting point for selection is the production process of stainless steel bolts, and the method depends on the size and shape of the stainless steel bolts, as well as the quantity produced.

　　302 type is used for machined screws and self-tapping bolts.

　　 303 type In order to improve the cutting performance, a small amount of sulfur is added to the 303 type stainless steel, which is used to process nuts with bar materials.

　　304 type is suitable for processing stainless steel bolts by hot heading process, such as longer size bolts and large diameter bolts, which may be beyond the scope of cold heading process.

　　305 type is suitable for processing stainless steel bolts by cold heading process, such as cold-formed nuts and hexagonal bolts.

　　 309 type and 310 type, their Cr content and Ni content are higher than 18-8 type stainless steel, suitable for stainless steel bolts working at high temperature.

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

　　321 type and 347 type, 321 type contains relatively stable alloying element Ti, 347 type contains Nb, thus improving the material's resistance to intergranular corrosion. It is suitable for stainless steel standard parts that are not annealed after welding or are in service at 420～1013℃.