基于GCr15轴承钢淬回火组织的时效尺寸变化预测模型

Prediction of Dimensional Change of GCr15 Bearing Steel during Aging Based on Quenched and Tempered Microstructure

轴承钢在服役过程中的尺寸变化及尺寸稳定性对轴承的精度保持性和服役性能有着重要影响。针对轴承钢尺寸变化行为的预测问题,提出基于高碳铬轴承钢亚稳组织转变的时效尺寸变化预测模型。对比时效尺寸变化的预测值与测量值,预测值的相对误差不超过5%,两者吻合良好。然后,基于时效尺寸变化预测模型分析淬火和回火工艺对时效阶段尺寸变化的影响规律。分析结果显示,淬火工艺决定了时效尺寸变化程度的上下限,且上限随淬火加热温度提高而增加。回火工艺决定其起点,且提高回火温度可以显著降低时效尺寸变化程度。分析结果还显示,淬火态GCr15轴承钢在180℃等温回火2 h即可获得较高的尺寸稳定性。该时效尺寸变化预测模型可为预测GCr15轴承时效尺寸变化程度及优化和控制淬回火工艺提供依据。

The dimensional change and its stability of bearing steel during service are of great importance to the precision retaining ability and service performance of bearings. To forecast the dimensional changes of bearing steel during aging, a prediction model based on microstructure state of quenched and tempered high carbon chromium bearing steel is proposed. According to the microstructure transformation kinetics and unit cell volume during tempering, a tempering dimension change model is established and the predicted dimensional changes are in good agreement with the experimental results. Based on the prediction model, the effects of quenching and tempering process on the dimensional changes of aging stage are analyzed. The analysis results show that the quenching process determines the upper and lower limits of dimensional change during aging, and the upper limits increase with the increase of heating temperature. Tempering process determines its starting point, and increasing tempering temperature can significantly reduce the dimensional change during aging. The results also show that quenched GCr15 bearing steel can obtain high dimensional stability after isothermal tempering at 180 ℃ for 2 h. This prediction model can provide the theoretical basis for the prediction of dimensional changes during aging and the optimization of quenching and tempering process for high carbon chrome bearing steel.