K418合金車用增壓渦輪熱裂傾向性分析及預測Hot tearing susceptibility analysis and prediction of K418 superalloy for auto turbocharger turbine wheel

為解決K418合金用于澆注車用增壓渦輪時出現(xiàn)的熱裂問題，采用有限元模擬軟件ProCAST的熱彈塑性模型，對不同澆注工藝下K418合金車用增壓渦輪的充型和凝固過程進行模擬，通過對溫度場、固相分數(shù)和應力場模擬結果的分析，預測熱裂缺陷的形成傾向，模擬結果與實際情況基本吻合。分析結果表明，渦輪葉稍處產(chǎn)生熱裂的根本原因是凝固過程中產(chǎn)生了拉應力，應力值越大，鑄件處于熱裂敏感區(qū)的時間越長，熱裂傾向性越大；采用較高的模殼溫度和較低的澆注溫度有利于降低鑄件的熱裂傾向。

The filling and solidification processes under different pouring processes were simulated by the thermal elasto-plastic stress model in finite element simulation software ProCAST in order to solve the hot tearing problem in the K418 superalloy auto turbocharger turbine wheel. The susceptibility of hot tearing defects was predicted by analyzing the simulation results of temperature field, solid fraction and stress field. The simulation results agree well with the real circumstances. The analysis results show that the main reason for the hot tearing in the blade margin of turbine is the tensile stress induced during the solidification. Both the higher stress and the longer time in the hot tearing sensitive range will result in the higher hot tearing susceptibility of the casting. The higher shell temperature and the lower pouring temperature are advantageous to reducing the hot tearing susceptibility of the casting.

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