Effect of preaging on the precipitation behaviour of AlMgSi1

Abstract

Abstract AlMgSi1 alloys show a deteriorated artificial aging behaviour if they are stored at room temperature between solution treatment and artificial aging (“negative room temperature storage effect”). The present work deals with a preaging step – immediately after solution treatment – which reduces this effect. Mechanical tests and electric resistivity measurements demonstrate that preaged samples are stable even for long room-temperature storages, and they have an excellent artificial-aging behaviour. Preaging may be also beneficial if artificial aging is carried out at higher temperatures to reduce aging time. Higher aging times are combined with a loss of strength and ductility, which is less pronounced for preaged samples. TEM investigations demonstrate that preaged samples show finer precipitates than conventionally-aged ones.