Whether it is stainless steel plate or heat-resistant steel plate, austenitic steel plate has the best overall performance, sufficient strength, good plasticity and not too hard, which is one of the reasons they are widely used. Austenitic stainless steel is similar to the vast majority of some other metal structural materials, its tensile strength, yield strength and hardness, with the lowering of the ambient temperature and increase; plasticity will be reduced with the lowering of the temperature and with it. In the temperature range of 15 to 80 ℃, the tensile strength increases more uniformly. More importantly: as the ambient temperature decreases, the impact toughness decreases more slowly, and there is no brittle transition temperature. So stainless steel at low temperatures can maintain sufficient plasticity and toughness. The heat resistance of stainless steel refers to the high temperature, both oxidation resistance or resistance to corrosion of gaseous media performance that is thermal stability.
The influence of chromium
Chromium is the most important alloying element in austenitic stainless steel, austenitic stainless steel stainless and corrosion resistance is obtained mainly due to the role of the club mass, chromium promotes the passivation of steel and make steel to maintain a stable passivation state results. The effect of chromium on performance: in general, as long as the austenitic stainless steel to maintain a complete austenitic organization and no δ ferrite formation, etc., only to improve the chromium content of steel will not have a significant impact on the mechanical properties, chromium on austenitic stainless steel performance is the greatest impact on corrosion resistance, mainly as follows: chromium to improve the steel resistance to oxidizing media and acid chloride media performance; in nickel and molybdenum and copper composite role, chromium to improve the steel resistance Some reducing media, organic acids, urea and alkali media performance; chromium also improve steel resistance to local corrosion, such as intergranular corrosion. Pitting corrosion, crevice corrosion and the performance of a certain condition of stress corrosion. Although according to the study of molybdenum resistance to pitting and crevice corrosion for chromium about 3 times, nitrogen for chromium 30 times, but a large number of studies, austenitic stainless steel if no chromium or chromium content is low, molybdenum and nitrogen resistance to pitting and crevice corrosion will be lost or not significant enough.
The role of chromium on austenitic stainless steel stress corrosion resistance, with the experimental media conditions and the actual use of the environment varies, in MgCl2 boiling solution, the role of chromium is generally harmful, but in aqueous media containing Cl- and oxygen, high temperature and high pressure water and pitting corrosion for the origin of stress corrosion conditions, improve the chromium content of steel is beneficial to stress corrosion resistance, at the same time, chromium can also prevent austenitic stainless steel and alloy Due to the increase in nickel content and the tendency of intergranular stress corrosion, the cracking (NaOH) stress corrosion, the role of chromium is also beneficial, chromium in addition to austenitic stainless steel corrosion resistance has an important impact, but also significantly improve the performance of this type of steel oxidation, sulfide and melt salt corrosion resistance.
Post time: Feb-10-2023