| PANG Ming,TAN Wen-dan.Effect of Preheating Temperature on Residual Stress Field of Laser Melting RuT300 Valve Seats[J],48(8):296-301 |
| Effect of Preheating Temperature on Residual Stress Field of Laser Melting RuT300 Valve Seats |
| Received:November 23, 2018 Revised:August 20, 2019 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2019.08.039 |
| KeyWord:laser melting preheating temperature RuT300 valve seats residual stress crack suppression |
| Author | Institution |
| PANG Ming |
Civil Aviation University of China, Tianjin , China |
| TAN Wen-dan |
Civil Aviation University of China, Tianjin , China |
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| Abstract: |
| The work aims to study the effect of preheating temperature on residual stress field of laser melting RuT300 valve seats, so as to break through the bottleneck of crack suppression technology of laser melting valve seats made of vermicular graphite cast iron RuT300 and provide support for parameter optimization of crack suppression in engineering. Based on the thermal elastoplastic theory, a mathematical and physical model for residual stress field analysis of laser melting RuT300 valve seats was established. The effects of preheating temperature, laser melting parameters and changes of material performance parameters on residual stress were considered in the model. The effect of preheating temperature on residual stress field of laser melting RuT300 valve seats was closely related to the cooling rate of molten pool, the peak temperature, etc. When the preheating temperature was between 25 ℃ and 150 ℃, stress reduction due to the mismatch of thermal expansion deformation in space of laser melting RuT300 valve seats caused by the decrease of cooling rate with the increase of preheating temperature played a major role, thus decreasing circumferential residual stress value of valve seats with the increase of preheating temperature. When the preheating temperature was between 150 ℃ and 250 ℃, the increase of stress caused by the intensified thermal expansion deformation induced by the peak temperature rise with the increase of preheating temperature played a major role, resulting in the increase of circumferential residual stress value of valve seats with the increase of preheating temperature. The variation of preheating temperature affects the cooling rate and the peak temperature of valve seats, and the variation of residual stress value is the result of the combined effect of cooling rate and peak temperature of valve seats. By adjusting and controlling the preheating temperature reasonably, the residual stress value of laser melting RuT300 valve seats can be reduced to the minimum, thus reducing the tendency of crack formation of laser melting valve seats. |
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