A356铝合金半固态连铸坯半固态剪切变形特性研究

摘要

The experiments to explore the rheologic properties of semisolid continuous casting billets of A356 alloy in the semisol id state have been carried out by means of the multifunctional rheometer.The obt ained results show that the deformation rate is increased with the increasing lo ading time,the maximum strain can reach 120%,which is one time larger than that of th e traditional mold casting billet;and that the strain can be rapidly eliminated to 10% after unloading.Moreover,it is experimentally found that there is a criti c stress to make the billet deformed,named critic sheer stress.The value of it i s increased with the decrease of the heating time.The rheologic properties can b e expressed by the five elements mechanical model H1－〔N1|H2〕－〔N2|S〕 and is modified with the increase of heating time.%利用多功能流变仪对A356铝合金半固态连铸坯在半固态 温度下进行了静态剪切变形试验。结果表明，在恒定载荷作用下，变形速度随加载时间延长 而增大，其最大变形量可达120%以上，比普通连铸坯料提高一倍以上。卸载后变形可以迅速 恢复，残余变形量只有10%左右。此外，这种坯料在半固态温度下存在一个发生变形的临界 切应力，其数值随保温时间的延长而减小。半固态连铸坯的流变特性可以用H1－〔N1 |H2〕－〔N2|S〕五元件机械模型来描述，并随保温时间的延长而改善。