带有空间双裂纹的金属拉伸试件脉冲放电止裂与力学性能

CRACK PREVENTING USING ELECTROMAGNETIC HEATING AND MECHANICAL PROPERTY IN METAL TEST PIECE WITH DOUBLE SPACE CRACK

为解决电磁热裂纹止裂技术应用的关键问题,采用数值模拟和试验的方法研究金属试件止裂和止裂后的力学性能。应用热—电耦合的分析方法模拟研究带有预制双裂纹的标准合金钢拉伸试件脉冲放电止裂瞬时的温度场,并为实施止裂试验提供了工艺参数;应用ZL-2超强脉冲电流发生装置实现了空间双裂纹的止裂试验,放电后两个裂纹尖端附近均熔化形成焊口,裂尖的曲率半径在放电瞬间增大了几个数量级,可达到止裂的目的;借助微机控制电子万能试验机对止裂后的合金钢试件进行拉伸试验,并对止裂后裂尖处金相组织进行分析,研究断口的形态。研究结果表明:在合适的脉冲放电电压下,电磁热效应可以实现空间裂纹止裂,并有效地提高试件的力学性能。

For solving the key problem in application of crack arrest using electromagnetic heating, the crack preventing and the mechanical property of metal test piece is studied by using numerical simulation and experiment methods. The temperature around the crack tips is simulated when crack arresting in alloy tension test piece with prepared double cracks by pulse current discharge, the thermal-electrical coupling theory is applied in numerical simulation, and the results of numerical simulation are applied to confirm the technique parameter of crack prevention. The crack arrest experiment is finished by using super pulse current generating equipment ZL-2. The deposit joints can be formed around the crack tips, and the radius of curvature around the crack tip will be increased by some orders of magnitude instantly after pulse current discharged. So the goal of crack preventing can be reached. After crack arresting, the tension test is applied by using PC-control universal tester. The microstructure around crack tip and the fracture are analyzed. The research results show that if the pulse discharged voltage is suitable, the space crack arrest can be realized, and the mechanical property of tension test piece grows up after crack prevention.