IN718合金熱機(jī)械疲勞試驗(yàn)非穩(wěn)態(tài)溫度場(chǎng)的數(shù)值模擬IN718合金熱機(jī)械疲勞試驗(yàn)非穩(wěn)態(tài)溫度場(chǎng)的數(shù)值模擬Numerical simulation of transient temperature field during thermomechanical fatigue of IN718 alloy 基于熱機(jī)械疲勞試驗(yàn)，建立IN718高溫合金感應(yīng)加熱過(guò)程中電磁場(chǎng)和溫度場(chǎng)耦合的數(shù)學(xué)模型，對(duì)試樣在循環(huán)加熱條件下的非穩(wěn)態(tài)溫度場(chǎng)進(jìn)行仿真，采用電子背散射衍射技術(shù)對(duì)試樣上的晶粒尺寸進(jìn)行檢測(cè)并對(duì)其數(shù)據(jù)進(jìn)行統(tǒng)計(jì)分析。結(jié)果表明：綜合傳熱系數(shù)和風(fēng)機(jī)電壓呈正相關(guān)的關(guān)系；試樣徑向上存在溫度梯度且隨時(shí)間變化，最大溫差為5 ℃左右，符合試驗(yàn)要求；低周疲勞試樣徑向上不同點(diǎn)的平均晶粒尺寸均有所增長(zhǎng)，且增長(zhǎng)幅度基本相同；由于溫度梯度的影響，熱機(jī)械疲勞試樣徑向上的晶粒尺寸分布不均勻，中心位置和表面位置的平均晶粒尺寸增長(zhǎng)幅度分別為16.94%和5.3%。 A mathematic model describing the induction heating process of IN718 superalloy was developed by coupling the electromagnetic field with the temperature based on the thermomechanical fatigue (TMF) test. The transient temperature fields of the specimen under cyclic heating condition were simulated. After the fatigue test, the grain size of the specimen was measured by electron backscattered diffractometry and the data were analyzed. The results indicate that the comprehensive heat transfer coefficient increases with the increase of the fan voltage. The temperature gradient in the radial direction of the specimen changes with time and the maximum of temperature difference is about 5℃, which meets the requirements of the test standard of TMF. The grain sizes of specimen in the radial direction increase at almost the same rate after the low cycle fatigue test. However, the grain sizes of specimen in the radial direction distribute unevenly after the thermomechanical fatigue test, meanwhile the average grain size at the center and the surface increases by 16.94% and 5.3%, respectively.
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