基于Mn配分的700T低碳钢的残余应力演变规律

Residual stress evolution of 700T low carbon steel based on Mn partition

回火是改善材料残余应力的必要手段,但低碳钢因其碳含量较少,导致回火过程残余应力的松弛度不足,制约了低碳高强钢的生产和应用。通过应力实测、组织表征和塑性行为分离等研究了低碳钢不同回火阶段的塑性行为及其对残余应力的影响。结果表明:Mn配分是低碳钢残余应力松弛的主要机制。在600~650℃Mn配分阶段保温15 min,试验钢的残余应力水平由388.23 MPa下降至88.11 MPa,为回火前的22.70%,试验钢的屈服强度、抗拉强度及断后伸长率分别由618 MPa、728 MPa和13.75%上升至701 MPa、807 MPa和16.77%。因此,利用低碳钢在回火过程中的Mn配分行为,不仅可以充分松弛其内部的残余应力,而且可以进一步提高其力学性能。

Tempering is a necessary means to improve the residual stress of materials.However,due to the low carbon content of lowcarbon steel,the relaxation of residual stress during tempering is insufficient,which restricts the production and application of low-carbon high-strength steel.The plastic behavior of low carbon steel at different tempering stages and its effect on residual stress were studied by stress measurement,microstructure characterization and plastic behavior separation.The results show that Mn partition is the main mechanism of residual stress relaxation in the low carbon steel.After tempering at 600-650℃for 15 min,the residual stress of the experimental steel is reduced from 388.23 MPa to 88.11 MPa,22.70%of that before tempering,and the yield strength,tensile strength and elongation are increased from 618 MPa,728 MPa and 13.75%to 701 MPa,807 MPa and 16.77%,respectively.Therefore,the Mn partition behavior of low carbon steel during tempering can not only fully relax its internal residual stress,but also further improve its mechanical properties.