【摘要】 通过热模拟实验与组织观察,研究了盾构机轴承套圈用钢42CrMo在热变形中的动态再结晶行为以及锻造镦粗过程道次压下量对组织精细化与均匀化的影响。结合动态再结晶规律,对锻造镦粗过程中的不同压下规程下的组织进行预测,得到在实验条件下:当单道次变形量为1 mm和2 mm时,变形过程中未发生动态再结晶而发生静态再结晶时,晶粒细化不明显,道次压下量越大,变形组织越细小;当单道次变形量为4 mm和8 mm时发生动态再结晶后,变形组织明显细小,但由于处于部分再结晶区,组织存在混晶现象。实验结果有效地验证了预测的准确性。因此,为了使镦粗过程发生动态再结晶以获得均匀细小的组织,在单道次变形量为40%条件下,应提高镦粗锻造温度到1100℃以上;在镦粗锻造温度为1050℃条件下,应加大单道次变形量到52.7%以上。更多还原

【Abstract】 The dynamic recrystallization behaviors of 42CrMo steel for bearing ring of shield tunneling machine during hot deformation and the effect of reduction in pass on the refinement and uniformity of microstructure during upsetting in forging were studied by hot simulation tests and quantitative metallography.Prediction of microstructure under different reduction schedules during upsetting in forging was conducted based on the dynamic recrystallization research.It is concluded that only static recrystallization occurs during deformation when reduction in pass is 1 mm or 2 mm,and the microstructure is refined by the increase of reduction in pass.The microstructure is obviously refined when the reduction in pass increases to 4 mm or 8 mm,while the deformation lies on the partly dynamic recrystallization zone and the mixed grains appear.The predicted results are confirmed by the experimental results.Consequently,in order to make sure fully dynamic recrystallization happen and achieve uniform and refined microstructure during upsetting process,forging temperature should be elevated to 1100 ℃ when reduction in pass is 40% or the reduction in pass is increased to over 52.7% when forging temperature is 1050 ℃.更多还原