Direct deformation spheroidization (DDS) of carbides in warm conditions can improve the microstructure and performance of bearing steel. In this study, based on the carbide spheroidization mechanism, a set of multiaxial constitutive equations was developed to predict the microstructure evolution of bearing steel 52100 during warm skew rolling (SR). The derived multiaxial constitutive equations were implemented in DEFORM-3D software through a user subroutine. FE simulation of warm SR was performed to predict the formation and microstructure evolution of bearing steel balls (BSBs). The distribution of the normalized dislocation density, carbide phase transformation fraction and carbide spheroidization fraction within BSBs was predicted via FE simulation of warm SR. To validate the FE simulation results, warm SR experiments were conducted to produce BSB specimens with 30 mm diameter. The microstructure of BSB specimens was observed to analyze their microstructure distribution in the longitudinal and transversal sections. The predicted and experimental results were compared, and the results show that the predicted carbide spheroidization distribution agrees well with the experimental results. This indicates that the formation and microstructure of BSB during warm SR can be predicted well using the derived multiaxial constitutive equations.

中文翻译：

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温斜轧中轴承钢球形成组织的数值预测与实验验证

碳化物在温暖条件下的直接变形球化（DDS）可以改善轴承钢的组织和性能。在这项研究中，基于碳化物的球化机理，建立了一套多轴本构方程来预测52100轴承钢在热斜轧（SR）过程中的组织演变。通过用户子例程在DEFORM-3D软件中实现了导出的多轴本构方程。进行了热SR的有限元模拟，以预测轴承钢球（BSB）的形成和微观组织演变。通过BSB预测归一化位错密度，碳化物相变分数和碳化物球化率的分布有限元模拟温暖的SR。为了验证有限元模拟结果，进行了热SR实验，以生产直径为30 mm的BSB标本。观察BSB试样的微观结构，以分析其在纵向和横向截面中​​的微观结构分布。比较了预测结果和实验结果，结果表明预测的碳化物球化分布与实验结果吻合良好。这表明，使用导出的多轴本构方程可以很好地预测温暖SR期间BSB的形成和微观结构。