S355J2W钢自阻加热弯曲成形回弹控制与质量分析

为研究S355J2W高强钢板自阻加热弯曲成形过程中电流密度对回弹的影响及成形件的质量,设计了自阻加热V形弯曲试验和自阻加热几字形弯曲试验,通过改变自阻加热时加载的电流密度大小对成形后零件的回弹现象进行研究.根据试验结果,选择成形精度最高、回弹现象最小的几字形零件进行质量分析,并将其与室温成形的几字形零件进行对比,从而研究自阻加热弯曲成形工艺的优势.将所选取的两个几字形零件分别划分为9个不同的区域,对不同区域的试件进行显微组织观察与力学性能测试,将单向拉伸试验、冲击落锤试验与显微硬度的测试结果作为评价成形件质量的标准,同时将两个零件在力学性能上的差异与显微组织观察的结果联系起来.结果表明:随着电流密度的增大,S355J2W钢自阻加热弯曲成形过程中的回弹得到改善;相比于室温成形的几字形零件,采用自阻加热弯曲成形工艺可以很大程度地改善回弹现象;并且自阻加热成形件的组织更加均匀,其力学性能指标,如抗拉强度,延伸率,冲击韧性和显微硬度也有所提高.

Study on the springback and quality of S355J2W steel in resistance heating bending

In order to investigate the influence of the current density on the springback and quality of S355J2W steel parts formed by resistance heating bending, the V-shaped and cap-shaped resistance heating bending experiments were designed.The springback of steel parts after forming was studied by varying current densities in resistance heating.According to the test results, the quality of the parts with the highest forming accuracy and the smallest springback were selected to compare with the parts formed at room temperature to study the advantage of resistance heating bending.The selected two parts were divided into 9 different regions.The microstructure and mechanical properties of these regions, such as strength, hardness, elongation, and impact toughness were used as the standard to evaluate the quality of the formed parts.Moreover, the differences in mechanical properties of the two parts were explained by the results of microstructural observation.The results showed that the springback of S355J2W steel in resistance heating bending was improved with the increase current density.Compared to the parts formed at room temperature, resistance heating bending process can greatly improve the springback and quality.At the same time, the mechanical properties were also improved in resistance heating bending.