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本文用TEM、SEM及X射线衍射仪研究了GCr15轴承钢热轧未退火料经780℃温挤压,短时间加热预处理,再重新加热到855℃淬火及回火后的显微组织形态和亚结构。结果表明,形变热处理使碳化物细化,细小AlN质点的析出可以钉扎晶界,使奥氏体晶粒细化。与此同时马氏体中的位错组态也发生变化——板条马氏体及孪晶马氏体碎化,位错密度增加。钢球滚道区域的残留奥氏体在交变负荷作用下产生诱发马氏体相变。上述因素使经双细化工艺处理的GCr15钢疲劳寿命比常规处理的提高2倍多。
In this paper, by TEM, SEM and X-ray diffraction GCr15 bearing steel hot-rolled unannealed material by 780 ℃ warm extrusion, short-time heating pretreatment, and then reheated to 855 ℃ after quenching and tempering the microstructure and Sub-structure. The results show that the deformation heat treatment can refine the carbides, and the precipitation of fine AlN particles can pin the grain boundaries and refine the austenite grains. At the same time, the dislocation configurations in martensite also changed - lath martensite and twin martensite fragmentation, dislocation density increased. Residual austenite in the ball raceway region induces martensitic transformation under alternating load. The above factors make the fatigue life of GCr15 steel treated by double refinement process more than twice as much as conventional treatment.