(1. 北京航空航天大學(xué) 材料科學(xué)與工程學(xué)院，北京 100191；
2. 中國航發(fā)北京航科發(fā)動機控制系統(tǒng)科技有限公司，北京 100191)
摘 要: 金屬表面熔覆處理是改善其耐磨性的有效手段，但熔覆過程溫度變化較快，不易于直接測量。基于ANSYS模擬計算獲得熔覆層溫度變化，并進行組織分析，構(gòu)建工藝-溫度-與組織性能之間的關(guān)系規(guī)律。利用氬弧作為熱源在銅基體上微區(qū)熔凝制備錫青銅熔覆層。通過金相顯微鏡、電子探針等對熔覆過程溫度場不同位置處的微觀組織觀察分析，確定微觀組織和熱流密度之間的定性關(guān)系。通過對微小熔池內(nèi)部溫度分布的數(shù)值模擬和微觀組織的觀察分析，建立熔池內(nèi)部晶體形態(tài)、大小、分布和過冷度與冷卻速率的關(guān)系模型，重點對錫青銅熔覆層中柱狀晶向等軸晶的轉(zhuǎn)變進行研究。結(jié)果表明：晶粒尺寸、枝晶臂間距、析出相δ相和單質(zhì)Pb大小與熱流密度負相關(guān)，確定了柱狀晶/等軸晶轉(zhuǎn)變(CET轉(zhuǎn)變)與熱流密度的數(shù)學(xué)模型。通過對模擬參數(shù)的調(diào)整可將該模型擴展應(yīng)用至不同材料微區(qū)熔覆制備工藝。
關(guān)鍵字: 微區(qū)熔覆；凝固組織；有限元模擬；熱流密度；CET轉(zhuǎn)變
（1. School of Material Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing100191, China;
2. China Aero Beijing Aero Engine Control System Technology Co., Ltd., Beijing 100191, China）
Abstract:The metal surface cladding is an effective means to improve the wear resistance of the metal, but the temperature of cladding process changes rapidly and is not easy to be measured directly. The temperature change of cladding layer was obtained based on ANSYS simulation calculation, and the relationships between process, temperature and microstructure were established. The tin bronze cladding layer was prepared on the copper substrate, using argon arc as the heat source. The qualitative relationship between the microstructure and heat flux was determined by analyzing microstructure at different positions of the temperature field during cladding process. Through the numerical simulation of the temperature distribution in a small molten pool and analyses of microstructures, the relationship model of the crystal form and size, super-cooling degree and cooling rate was proposed to determine. The results show that the grain size, the dendrite arm spacing and the size of precipitate phase are negatively correlated with the heat flux, and the model of columnar crystal/equiaxial crystal transition (CET transition) and heat flux was established. By adjusting the simulation parameters, the model can be extended to different materials micro-zone cladding processes.
Key words: microzone cladding; solidification microstructure; finite element simulation; heat flux; CET transition
