1.41%C超高碳钢淬火高温回火球化组织的研究

Investigation on spheroidized microstructure of 1.41%C ultra-high carbon steel after quenching and high tempering treatment

采用淬火+高温回火热处理对碳的质量分数为1.41%超高碳钢进行球化处理,研究碳化物超细化的机理,确定最佳的球化工艺参数。结果表明:在850～1100℃范围内淬火时,随着温度的上升,碳化物不断溶入奥氏体,使粗大碳化物颗粒变小,回火后不仅从针状马氏体中析出均匀细小的碳化物,同时在残余奥氏体中也析出大量均匀细小的碳化物,碳化物数量增加。钢中含有抑制碳化物长大的Al和Cr元素,在550～750℃高温回火时,温度越高球化效果越好,即使在1100℃淬火+750℃回火后碳化物颗粒尺寸仍然保持在0.1～0.3μm。

An ultra-high carbon steel containing 1.41%C （mass fraction） was spheroidized by quenching and high temperature tempering treatment. The formation mechanism of uhrafine carbides was investigated, and the optimal spheroidizing parameters were determined. The results show that the carbides are dissolved into the austenite progressively with the increase of quenching temperature in the range of 850-1 100 ℃, and thus the coarse carbides are refined. After tempering, the fine carbides are uniformly precipitated not only from acicular martensite, but also from retained austenite, thus increasing the amount of carbides. As A1 and Cr elements can inhibit the growth of the carbides, the higher tempering temperature is beneficial for spheroidization in the range of 550-750 ℃. The size of carbides is in the range of 0.1-0.3 μm even though the steel was quenched at 1 100 ℃, followed by tempering at 750 ℃.