What are the materials used in stainless steel screws?

What are the commonly used stainless steel screws?
: 1, precipitation hardening stainless steel and is used for high strength and corrosion resistant stainless steel stainless steel screws. 17-4PH and PH15-7Mo can get higher than the usual strength of 18-8 stainless steel.
2, martensite stainless steel, hardness in good 35-45HRC machining performance, the type 410 and 416 type can be strengthened by heat treatment, for general purpose heat corrosion resistant stainless steel screws. Free cutting stainless steel, type 420, type 416 slightly higher sulfur content. To improve the mechanical properties of the sulfur content of R0.15% can be improved by heat treatment. The maximum hardness value of 53-58HRC for high strength stainless steel screws.
3, austenitic stainless steels: representative grades is chromium for about 18%, nickel containing 8% chromium nickel austenitic stainless steel, austenitic stainless steel alloying elements the basic is chromium and nickel. Often referred to as 18-8 stainless steel, chromium and nickel composition basically guarantees the microstructure of the steel is stable austenite.
, 4 ferritic stainless steel, corrosion resistance and heat resistance than type 410, type 430 ordinary steel. Magnetic, but it can not be strengthened by heat treatment, and is suitable for corrosion resistance and heat resistance of slightly higher strength requirements of stainless steel screws in general.
, 5 austenitic stainless steel: the so-called "18-8" the four type austenitic stainless steel. Whether it is corrosion resistant, commonly used models for 302, 303, 304, 305 or four models, its mechanical properties are similar. The starting point is production process of stainless steel screws, stainless steel screws and the method depends on the size and shape, but also depends on the number of production.
Type 302 to use mechanical processing and self tapping screw bolt. Type 303 stainless steel by adding a small amount of sulphur, type 303 in order to improve the cutting performance. For the bar nut processing. For example, a long bolt type 304 specifications, suitable for the processing of stainless steel screws during hot upsetting process. Large diameter bolts, are beyond the scope of the cold heading process. For example, cold forming nut, six angle bolt. The 305 type is suitable for the cold heading process of stainless steel screws. The Cr content and Ni content were higher than those of type 18-8 stainless steel, type 309 and type 310. Stainless steel screw suitable for working at high temperature. All containing alloying elements Mo and therefore its high temperature strength and corrosion resistance than the 18-8 type stainless steel, 316 and 317. Type 321 contains more stable alloy element Ti, 347 type Nb, which improves the resistance to intergranular corrosion. Stainless steel standard parts, Type 321 and 347, which are suitable for welding without annealing or serving at 420-1013.