QT600球墨铸铁激光淬火相变层残余应力测试研究

Study on residual stress of QT600 nodular cast iron hardened by laser quenching

利用CO2激光器对QT600球墨铸铁进行了激光淬火处理试验,用X-350A型X射线应力仪测定QT600激光淬火后的表面及其断面残余应力规律,分析了QT600激光淬火后的残余应力形成机理。试验结果表明,在CO2激光工艺参数为输出功率P=800-1200W、光斑直径=3.5-4.0mm、扫描速度V=6-8mm/s的条件下,QT600激光淬火后的残余应力均为压应力,其值在-250MPa以上。在QT600材料表面及断面上测定了Ψ=0°4、5°和90°方向上的残余应力,其值的变化范围小,表明淬火后材料组织结构比较均匀,无明显织构,有利于提高材料的使用寿命。

QT600 nodular cast iron was processed with laser quenching by using a CO2 laser. The distribution of residual stress on surface and in hardened layer of laser quenching sample were studied with a X-ray stress analyzer (X-350A type). The forming mechanism of the residual stress was discussed. The results show that the compressive residual stresses of the laser quenched sample is higher than- 250 MPa under quenching parameters of the power P = 800-1200 W, laser spot diameter Φ = 3.5-4.0 mm and scanning velocity V = 6-8 mm/s. The residual stresses on surface and in hardened layer of the sample at the directions of Ψ-0°, 45° and 90° were measured, respectively. The results show that no significant difference is observed for the residual stresses in different directions. It is indicated that there are no obvious texture in the laser quenched QT600 cast iron.