淬火温度对40Cr13塑料模具钢耐腐蚀性能的影响

对40Cr13塑料模具钢进行不同温度(960,1020,1080,1140℃)淬火处理,研究了淬火温度对该钢组织与硬度的影响,然后进行200℃的低温回火处理,通过浸泡试验与电化学测试研究了其耐腐蚀性能。结果表明:不同温度淬火后,试验钢组织均为淬火马氏体、碳化物与少量残余奥氏体;随着淬火温度的升高,组织变得粗大,碳化物减少,当淬火温度为1140℃时,组织中存在沿奥氏体晶界析出的网状碳化物;随着淬火温度的升高,试验钢的硬度先增加后减小。当淬火温度由960℃升高到1080℃,经回火后试验钢在FeCl₃溶液中的腐蚀速率减小,试验钢表面点蚀孔直径变小,数量增多,但深度变浅;试验钢在NaCl溶液中的自腐蚀电位增大,自腐蚀电流密度降低,腐蚀速率减小,腐蚀倾向降低;最佳淬火温度为1020℃,此时淬火马氏体组织较细小,硬度最大,回火后试验钢的耐腐蚀性能较好。

Effect of Quenching Temperature on Corrosion Resistance of 40Cr13 Plastic Die Steel

40Cr13 plastic die steel was quenched at different temperatures(960,1020,1080,1140℃),and the effect of quenching temperature on microstructure and hardness was studied.The steel was tempered at 200℃,and the corrosion resistance of the steel was studied by immersion test and electrochemical test.The results show that the microstructure of the test steel after quenching at different temperatures was composed of quenched martensite,carbides and a small amount of retained austenite.The microstructure became coarse with increasing quenching temperature,and the number of carbides decreased.When the quenching temperature was 1140℃,network carbides precipitated on austenite grain boundaries in the microstructure.The hardness of the test steel increased first and then decreased with increasing quenching temperature.When the quenching temperature increased from 960℃ to 1080℃,the corrosion rate of the test steel after tempering in FeCl₃ solution decreased;the diameter and depth of pitting holes on the surface of the test steel decreased,and the number increased.The free-corrosion potential of the test steel in NaCl solution increased,and the free-corrosion current density decreased;the corrosion rate decreased and the corrosion tendency decreased.The optimum the quenching temperature was 1020℃;at this point,the quenched martensite was relatively small,and the hardness was the largest;the corrosion resistance was relatively good.