Regardless of stainless steel plate or heat resisting steel plate, the comprehensive properties of austenitic steel is best, both sufficient strength, and has excellent plasticity and hardness is not high, one of the reason of which is that they have been widely used. Austenitic stainless steel is similar to the vast majority of other metal materials, and its tensile strength, yield strength and hardness increase with the decrease of temperature, while the plasticity decreases with the decreasing of temperature. Its tensile strength is more uniform in the temperature range of 15~80 C. More importantly, with the decrease of temperature, the impact toughness decreases slowly, and there is no brittle transition temperature. Therefore, the stainless steel can maintain sufficient plasticity and toughness at low temperature.
Stainless steel heat resistant performance is refers to the high temperature, not only has the oxidation resistance or the gas medium corrosion resistance performance namely the heat stability, at the same time in the high temperature double has enough strength namely the heat intensity.
The effect of chromium: chromium is the main alloying elements in austenitic stainless steel, austenite stainless steel stainless steel and corrosion resistance is mainly due to the quality will be promoted under the action of chromium steel passivation and make steel stable passivation results. Effects of chromium on the 1, the organization: in austenitic stainless steel in the formation and stabilization of iron chromium is a strong body element, narrow the austenite region, with the increase in steel content, appearance of ferrite in austenitic stainless steel (delta) organization, research shows that in Ni Cr austenitic stainless steel, when the carbon content is 0.1%, the chromium content of 18%, to obtain stable single austenite the required minimum nickel content, about 8%, in this regard, the commonly used 18Cr - 8Ni type Cr Ni austenitic stainless steel is chromium, nickel content ratio of one of the most suitable. In austenitic stainless steel, with chromium content Increased intermetallic phase (such as delta phase) forming tendency increases, when the steel containing molybdenum, chromium containing content will increase the formation of X will be equal, as mentioned earlier, sigma, Chi precipitates not only significantly reduce steel plastic and toughness, and under some conditions but also reduce the corrosion resistance of the steel, the improvement of chromium content in austenitic stainless steel can be the martensite transformation temperature of hydrocarbon (MS) decreased, thereby improving the stability of austenite matrix. Therefore, high chromium (such as more than 20%) of austenitic stainless steel even after cold working and low temperature treatment is also difficult to obtain martensitic organization.
Chromium is strong carbide forming elements, there is no exception in the austenitic stainless steel, austenitic stainless steel chromium carbides are common Cr23C6; when containing molybdenum or chromium in steel, are visible due Cr6C carbides formed under certain conditions on the performance of steel will have an important impact on them. The influence of chromium on performance, 2 general: to master, as long as the austenitic stainless steel remain completely austenite without delta ferrite formed body, improve the Cr content in steel not only has a significant influence on the mechanical properties, effects of chromium on performance of austenitic stainless steel is the largest corrosion resistance, the main performance is: to improve the performance of steel chromium oxidation resistant and acid chloride medium medium; in nickel and molybdenum and copper composite under the action of chromium resistant steel improve some reductive medium, organic acid, urea and alkali properties of medium chromium steel; improve localized corrosion For example, intergranular corrosion. Corrosion performance. Stress sensitivity of stadium gymnasium intergranular austenitic stainless steel are the major factors affecting the carbon content of steel in crevice corrosion and certain conditions, the effect of other elements on the intergranular stadium mainly depending on the dissolution and precipitation behavior of carbides in austenite and. Stainless steel, chromium can increase the solubility of carbon and chromium depletion reduced, thus increasing chromium content on intergranular corrosion resistance of austenitic stainless steel is good, chromium is very effective to improve the corrosion resistance of austenitic stainless steel corrosion and crevice, while there are molybdenum or molybdenum and nitrogen in steel, the chromium according to the research of strengthening, while Mo resistance gymnasium and crevice corrosion resistance of chromium is about 30 times times then, nitrogen and chromium, but a lot of research, such as austenitic stainless steel As a result, there is no chromium or chromium content is low, and the corrosion resistance of molybdenum and nitrogen will be lost or not significant.
The effect of chromium stress corrosion of austenitic stainless steel with medium resistance, experimental conditions and the actual use of the environment varies in MgCl2 in boiling solution, the role of chromium is generally harmful, but in the water medium containing Cl- and oxygen, high temperature and high pressure water and corrosion for the origin of stress corrosion conditions, improve Cr content in steel on stress corrosion resistance, at the same time, can also prevent the chromium austenitic stainless steel and nickel alloy as the content increased and prone to intergranular corrosion tendency of stress, the caustic stress corrosion (NqOH), chromium effect is beneficial, in addition to chromium has an important effect on the negative Austenitic stainless steel corrosion resistance, can significantly improve the steel antioxidant, anti - and anti salt corrosion resistance.