异种材料淬火过程的有限元模拟

FEM simulation of quenching process for dissimilar material welded using steel and titanium alloy

钛合金扩散焊接轴承钢材料由于含有钒、铜、镍中间层,在淬火过程中容易从多层材料界面处开裂。因此利用纳米显微力学探针测量了材料的弹性模量,然后采用ANSYS有限元软件对淬火中钛合金焊接轴承钢材料进行了有限元（FEM）模拟,根据得到的温度场以及应力场分布,找出了容易诱发界面处产生裂纹的原因。模拟表明淬火初期由于整体材料发生收缩而引起整体热应力的增加,淬火后期由于轴承钢发生马氏体相变,轴承钢体积开始膨胀,组织应力相应增加,抵消了一部分热应力的值,最终部件的残余应力是这两种应力共同作用的结果。高的淬火温度,增加了淬火过程中试件内部的应力值,容易引起过渡层处产生微裂纹从而导致局部开裂,因此,合适的淬火温度应取在830-860℃范围内且尽可能取偏其下限。

The material of bearing steel bonded on titanium alloy included V, Cu, Ni transition layers, which produced easily cracking on transition layer during quenching process. The elastic modulus of the materials was measured by nano indenter Ⅱ , and then the quenching process for bearing steel bonded on titanium alloy surface was simulated by FEM using ANSYS software. Based on the temperature and stress fields of integrated samples, which were obtained by simulation, the main reason of producing fracture on transition layers were found. Because integrated samples contract as it cooled during initial quenching process, the heat stress starts to increase. Subsequently, the martensitic transformation in bearing steel led to sample＇s cubic expansion, and the structure stress starts to increase and counteracts some heat stress, both of which induces the final residual stress distribution. The higher quenching temperature increases the internal stress of sample, which is easy to generate cracks, and then fracture occurs on transition layer, so the proper quenching temperature is in the range of 830 - 860℃, and the lower temperature is better.