不同基板预热温度对激光金属沉积成形过程热应力影响的研究

研究不同基板预热温度对激光金属沉积成形过程热应力的影响,对于降低成形过程的热应力,抑制成形过程裂缝的产生,减小成形过程试样和基板的翘曲变形具有非常重要的意义。根据有限元分析中的"单元生死"技术,编程建立了基板预热对激光金属沉积成形过程热应力影响的三维多道多层数值模拟模型,详细分析了基板未预热和分别预热到200℃、300℃、400℃、500℃、600℃时对沉积成形过程VonMise’s热应力、X方向、Y方向以及Z方向热应力的影响。在与模拟过程相同的参数下,利用镍基合金粉末分别在基板未预热和分别预热到300℃、400℃、500℃、600℃时进行了成形试验,试验的结果跟数值模拟结果吻合较好。

In order to decrease the thermal stress, restrain the generation of cracks, and reduce the shape distortion of sample and substrate, it is of great importance to have an in -depth understanding of the effects of different substrate preheating temperature on the thermal stresses during laser metal deposition shaping (LMDS) process. Based on the"element life and death"theory of FEA, a three -dimensional multi - track and multi -layer model for LMDS is developed. Through the model, the effects of substrate pre- heating on thermal stresses are deeply researched by setting the temperature of substrate at room temper- ature or 200℃, 300℃, 400℃, 500℃, 600℃. The distribution regularities of Von Mise’s effective stress, X-directional, Y-directional and Z -directional thermal stresses are obtained. LMDS experi- ments without substrate preheating or under300℃, 400℃, 500℃, 600℃ are carried out with nickel - based super alloy by using the same process parameters as in simulation. The results show good agree- ment with the numerical simulations.

国家高技术研究发展计划(863计划2002AA420060);;辽宁省教育厅高校科研项目(20060380)