无碳化物贝氏体钢渗碳后的深冷处理

采用热磁分析、显微硬度分析与直读光谱分析等相结合的方法,对无碳化物贝氏体钢进行渗碳后的深冷处理工艺优化。结果表明:无碳化物贝氏体钢在1193K渗碳空冷后,测试有效硬化层样品的热磁曲线,可以得到有效硬化层的深冷处理温度宜低于134K。经123K深冷处理和463K回火,有效硬化层残留奥氏体含量约为12.2%(质量分数)。通过深冷处理使渗碳钢近表面层得到显著硬化,再经低温回火使近表面层硬度均达到810HV_(1.0)左右,渗碳钢的硬度梯度分布趋于合理。

Cryogenic Treatment of Carbide-flee Bainite Steel After Carburizing

The cryogenic treatment (CT) process of carbide-free bainite steel after carburizing was optimized by the method combining thermal magnetic analysis,microhardness analysis and direct reading spectrometric analysis.The results show that cryogenic treatment temperature of the hardened layer should be lower than 134K by measuring thermal magnetic curve of the sample after carburizing at 1193K and air cooling (AC).After cryogenic treatment at 123K and tempering (T) at 463K,retained austenite content of the hardened layer is about 12.2％ (mass fraction).The near surface layer of carburized steel is hardened dramatically through the cryogenic treatment,and the hardness of near surface layer reaches about 810HV1.0 after low temperature tempering.The distribution of hardness gradient of carburized steel tends to be reasonable.