塑性变形与调质处理耦合作用对40Cr钢锭焊接接头疲劳性能的影响研究

Study on Fatigue Properties of 40Cr Steel Welded Joint under Plastic Deformation and Quenching & Tempering

本研究以40Cr钢锭为试验材料,利用拉-压对称循环载荷,通过疲劳断口形貌和S-N曲线,探究了镦粗变形与调质处理的耦合作用对40Cr钢锭焊接接头疲劳性能的影响。结果表明:经过镦粗+调质处理的焊接试样的疲劳强度优于母材和镦粗态焊接试样;疲劳断口SEM形貌观察表明,调质处理的焊接试样断口韧窝组织更加致密,韧性更好;镦粗+调质态的S-N曲线方程分别为lgN=63.6-24.1lgS,lgN=60.6-22.4lgS,lgN=83.4-31.2lgS。

40Cr steel ingot was selected as object.The effect of upsetting and quenching and tempering on fatigue property of 40Cr welded joint was investigated by fatigue fracture morphology and S-N curves under tensile-compress cyclic loading.The results showed that fatigue strength of welded sample after upsetting and quenching and tempering was better than that of base metal and welded sample after upsetting.SEM morphology of fatigue fracture showed that the dimple of welded sample fracture after quenching and tempering was more fine,accompanying with a better toughness.In addition,S-N curve equations for base metal,upsetting and quenching and tempering were also obtained respectively,lgN=63.6-24.1lgS,lgN=60.6-22.4lgS,lgN=83.4-31.2lgS.