China is a big country producing stainless steel, which is widely used in the field of springs, especially small springs. With the development of stainless steel production, many varieties have been developed naturally. More than 50 types have been developed at present, which basically meets domestic production. And development needs. Briefly introduced some new varieties currently developed.
1. What are the types of stainless steel materials for small springs?
(1) Initial formation of austenitic stainless steel system. In order to eliminate the grain boundary corrosion fatigue of stainless steel caused by carbon element, 0Cr18Ni9 and 00cr17ni2mo2 were developed. In order to improve its special properties, Cu, Ti, Nb, Mn, Cr, Si and N can be added.
(2) Development of nitrogen-containing stainless steel. In stainless steel, nitrogen is used instead of carbon. Nitrogen and carbon in austenitic stainless steel have many common characteristics. The effect of nitrogen stabilization of austenite is greater than that of nickel, which is equivalent to the effect of carbon stabilization of austenite. The combination of nitrogen and manganese can replace the more expensive nickel.
(3) Nitrogen is also one of the most effective solid solution strengthening elements in austenite. The affinity of nitrogen and chromium is less than the affinity of carbon and chromium, and precipitation of Cr2N is rarely seen in austenitic steels. Therefore, nitrogen can increase the strength of stainless steel without reducing its corrosion resistance.
(4) Development of super ferritic stainless steel for small springs. Ferritic stainless steel has good corrosion resistance and oxidation resistance, and its stress corrosion performance is superior to austenitic stainless steel. The price is cheaper than austenitic stainless steel. But there are also shortcomings such as poor weldability and high brittleness, which limits its production and use. By reducing the content of carbon and nitrogen, the addition of stable elements such as Ti, Nb, Zr, Ta, and the addition of weld metal toughening elements such as Cu, AI, V can improve the weldability and brittleness of ferritic steels.
(5) Development of small spring super austenitic steel. The content of chromium, molybdenum and nitrogen in super-austenitic steel is obviously higher than that of ordinary stainless steel. The most famous of them is 6% molybdenum steel (245s-Mo), which has good local corrosion resistance. Under the conditions of sea water, aeration, clearance and low-speed erosion, it has good pitting corrosion resistance (PI 40) and good resistance to stress corrosion. It is an alternative material for nickel-based alloys and titanium alloys