Effects of melt holding time on as cast microstructure and tensile properties of Sr-modified AS31alloy

摘要

Melt holding time has important influences on the modification effect of Sr modified AS31 alloy. Effects of different melt holding time (30min, 60min, 90min and 120min) at 700°C on as cast microstructure and tensile properties both at ambient temperature and elevated temperature of Sr-modified AS31 alloy were studied. There exist polyhedral shape, fine fibers shape and a few Chinese script Mg_2Si particles in Sr-modified AS31 alloys. And the average grain size is smallest in Sr-modified AS31 alloys with holding time at 700°C for 30min. The ultimate strength, yield strength and elongation at both ambient temperature and 150°C decrease gradually when the melt holding time increases from 30min to 120min. In the process of smelting of Sr-modified AS31. The burning loss of Sr element becomes more serious with the prolongation of melt holding time, which contributes to the modification effect reducing.