半固态挤压高硅铝合金二次加热的微观组织演变

Microstructure Evolution of an Extruded High Silicon Semi-solid State Aluminum Alloys During Reheating

本实验研究了半固态挤压高硅铝合金二次加热微观组织演变规律,以获得具有细小、近球状晶粒的组织。研究结果表明,二次加热功率和二次加热温度是影响二次加热过程的两大主要因素,随加热功率的增加,坯料心部和边部的组织差异变大,而随二次加热温度的升高,细小、不规则的晶粒逐渐长大并呈现出球化趋势。分析各工艺下的微观组织,得到适合于触变成形的二次加热工艺为:加热功率7 kW、加热温度530℃。此条件下获得的平均晶粒直径为35.2μm,抗拉强度为418.5 MPa。

The present work aimed to investigate the rule of reheating an extruded high silicon aluminum alloy into semi-solid state,so as to obtain a near globular microstructure.The results showed that reheating power and reheating temperature are two key parameters which affect considerably the reheating process.The increase of heating power can magnify the difference of microstructure for core and edge parts of billets.And with the increase of reheating temperature,the fine and irregular grains grow gradually and spheroidizes.The optimum reheating process parameters suitable for thixoforming were determined to be 7kW (power) and 530℃ (temperature),by analyzing the microstructure for different process.Under this processing condition,the average grain diameter of the resultant specimen experienced reheating was 35.2μm and the ultimate strength was 418.5 Mpa.