高能瞬时电脉冲处理对42CrMo钢组织与性能的影响

Effect of High-Energy and Instantaneous Electropulsing Treatment on Microstructure and Properties of 42CrMo Steel

采用XRD、SEM及TEM等手段,研究了42Cr Mo钢经高能瞬时电脉冲及传统处理后组织与性能的变化。结果表明,480 ms电脉冲处理后水冷(EPQ)处理可细化42Cr Mo钢的晶粒和组织,促进残余奥氏体及孪晶马氏体的形成,处理后的综合力学性能比传统淬火(TQ)态42Cr Mo钢提高32%;随后的180 ms电脉冲处理后空冷(EPT)处理可提高EPQ态42Cr Mo钢中残余奥氏体的稳定性,促进复相组织的形成,处理后的综合力学性能比其经传统回火(TT)处理后提高13.9%。

42 Cr Mo steel was widely used in many industry fields for its excellent hardenability and high temperature strength.Many transmission mechanisms and fasteners,such as roller and heat-resistant gear,are made of this steel.However,the ductility of 42 Cr Mo steel is relatively low after quenching and tempering.During high tempering Mo riched carbides at grain boundary and undecomposable martensite at low tempering are the main reasons for poor ductility of 42 Cr Mo steel.Grain refinement can enhance both strength and ductility significantly,but traditional refinement technology will cause intergranular oxidation so that strengthening effect was weak.Although thermomechanical treatment can achieve dynamic recrystallization,its refinement effect is unstable.Elecropulsing treatment,which makes significant change in microstructure and properties of metals,has been applied in many fields such as,modification of solidified microstructure of liquid metal,healing of fatigue crack,nanocrystallization of amorphous materials and so on.Moreover,this process can produce superior mechanical properties in metals.In order to improve the mechanical properties of 42 Cr Mo steel better,high-energy and instantaneous electropulsing treatment was applied.In this contribution,42 Cr Mo steel was subjected to traditional and electropulsing treatment individually.It was found that EPQ treatment（480 ms electropulsing treatment,water cooled） results in finer grain,promoting the formation of retained austenite and twin martensite;EPT treatment（180 ms electropulsing treatment,air cooled） can stabilize retained austenite in EPQ specimen and induce multiphase structure.Mechanical properties results indicate that strength-ductility balance of EPQ and EPQ＋EPT specimen are 32% and 13.9% higher than that of TQ（traditional quenched）and EPQ＋TT（traditional tempered） specimen respectively.