selecting stainless steel materials for fasteners
2022-12-09
In general, we need to consider the following aspects when selecting stainless steel materials for fasteners: 1. Requirements on mechanical properties of fastener materials, especially strength. 2. Requirements of working conditions on corrosion resistance of materials. 3. Requirements of working temperature on heat resistance (high temperature, strength, oxidation resistance) of materials. 4. Requirements for material processing performance in terms of production process. 5. Other aspects, such as weight, price and purchase, should be considered. Through the comprehensive and comprehensive consideration of these five aspects, the brand, variety, specification and material standard of fasteners are finally determined. What are the common stainless steel materials for fasteners? 1. Austenitic stainless steel The commonly used grades are 302, 303, 304 and 305, namely the so-called "18-8" austenitic stainless steel. Both corrosion resistance and mechanical properties are similar. The starting point for selection is the production process method of fasteners, which depends on the size and shape of fasteners, and also depends on the quantity of production. Type 302 is used for machined Screws and self tapping bolts. In order to improve the cutting performance of Type 303 stainless steel, a small amount of sulfur is added to the Type 303 stainless steel for processing nuts with bars. Type 304 is suitable for processing fasteners with hot heading process, such as bolts with long specifications and bolts with large diameters, which may be beyond the scope of cold heading process. Model 305 is applicable to processing fasteners by cold heading process, such as cold formed nuts and hexagon bolts. The Cr content and Ni content of Type 309 and Type 310 are higher than those of Type 18-8 stainless steel, and they are suitable for fasteners working at high temperatures. Type 316 and 317 both contain alloy element Mo, so their high temperature resistance and corrosion resistance are higher than those of type 18-8 stainless steel. 321 and 347, 321 contains relatively stable alloy element Ti, and 347 contains Nb, thus improving the resistance to intergranular corrosion. It is applicable to fasteners that are not annealed after welding or serve in 420~1013C.
Mr. andy