微Ti处理380CL车轮钢闪光对焊工艺与组织调控

Flash butt welding process and microstructure controlling of 380CL wheel steel with micro Ti treatment

关键词:  Ti微合金化|车轮钢|闪光对焊|硬度|热模拟

Key words:  Ti microalloying|wheel steel|flash butt welding|hardness|thermal simulation

摘要:

为解决轮辋闪光对焊(FBW)后微裂纹率和炸裂率偏高的问题，选取6.75 mm厚380CL车轮钢为研究对象，通过研究一元化闪光对焊参数对接头硬度的影响规律，建立闪光对焊温度场控制机制. 通过Ti微合金化技术思路进一步降低380CL闪光对焊焊缝的硬化倾向. 结果表明，为保证380CL闪光对焊后的成材率，需采取温度梯度较大的焊接规范，配合合理的顶锻量，从而获得最优的焊接接头. 在烧化量19 mm，钳口距离36 mm，烧化速度1.2 mm/s，带点顶锻时间0.5 s，顶锻量7 mm的闪光对焊参数下，6.75 mm厚380CL车轮钢可获得最低的硬度值140HV2. 对微Ti处理的380CL车轮钢进行了焊接热模拟，在1 000 ℃以上时的顶锻变形抗力降低，组织晶粒细化，显著降低了380CL闪光对焊后微裂纹率和炸裂率. 以上研究具备向高强度轮辋用钢的闪光对焊做进一步推广和应用示范.

Abstract:

In order to solve the problem of high micro-cracking rate and bursting rate after rim flash butt welding (FBW), the 380CL wheel steel with thickness of 6.75 mm is taken as the research object. By studying the influence of the unified flash butt welding parameters on the joint hardness, the control mechanism of the flash butt welding temperature field is established in this paper. The hardening tendency of the 380CL after FBW is further reduced by the Ti microalloying technology. It’s shown that in order to ensure the well-done production rate after flash butt welding of 380CL, it is necessary to adopt a welding specification with a large temperature gradient and a reasonable forging amount to obtain an optimal welded joint. Under the FBW parameters of the burnt amount of 19 mm, the jaw distance of 36 mm, the burning rate of 1.2 mm/s, the point upset forging time of 0.5 s, and the upset forging of 7 mm, the 380CL wheel steel with thickness of 6.75 mm can obtain the lowest hardness value of 140HV2. The welding heat simulation of the micro-Ti treated 380CL wheel steel was carried out. The deformation resistance of the upset forging at 1 000 °C or higher was reduced, and the grain refinement of the microstructure was remarkably reduced, which significantly reduced the micro-cracking rate and the burst rate after FBW of 380CL. The researches above have been further promoted and applied demonstration of FBW to high-strength rim steel.