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21 4N(5Cr2 1Mn9Ni4N)钢为汽车发动机排气阀用奥氏体耐热钢 ,该钢主要通过碳、氮化物沉淀硬化 ,在 70 0℃使用温度下具有高的强韧性和耐磨性 ,并具有冷热交变的组织稳定性和抗氧化性 ,广泛用于制造排气阀。由于 2 1 4N钢的热变形温度范围窄 ,该钢最佳锻轧温度为 110 0～ 980℃ ,冷加工硬化效应强 ,变形抗力较 1Cr18Ni9Ti钢高 30 % ,在锻造、热轧、冷拔时易产生裂纹。冷拔时两道次变形量≤ 1 10 ,钢中冷轧代替冷拔 ,加入提高钢的热塑性的稀土等微量元素和控制工艺参数是降低钢材表面裂纹、提高成品率的主要措施
21 4N (5Cr2 1Mn9Ni4N) steels are austenitic heat-resistant steels for automobile engine exhaust valves, which are primarily hardened by precipitation of carbon and nitride and have high toughness and wear resistance at temperatures up to 70 ° C. With alternating hot and cold tissue stability and oxidation resistance, widely used in the manufacture of exhaust valve. Due to the narrow heat treatment temperature range of 2 1 4N steel, the optimum forging temperature of this steel is 110 0 ~ 980 ℃, the cold work hardening effect is strong, the deformation resistance is 30% higher than that of 1Cr18Ni9Ti steel, and it is easy to be used in forging, hot rolling and cold drawing. Cracking. Cold drawing two times deformation ≤ 1 10, instead of cold drawing steel cold drawing, adding to improve the steel’s thermoplastic rare earth and other trace elements and control of process parameters is to reduce the surface of steel cracks and improve the yield of the main measures