種々の下部組織を持つ工業用純アルミニウム溶接熱影響部の再結晶挙動

Abstract

Recrystallization behaviour of commercial pure aluminium may be affected by the morphology of substructures.In this study, commercial pure Al of 10 mm thick plate was prepared. That was machined to the plates of various thickness, then these were full annealed at 600°C for 30 min.All plates were made equal to 2 mm thick plates by three kind of treatments, these were cold-rolling, cold-rolling and 200°C×30 min. annealing (in this report, quasi stabilized treatment=Q.S.T.) and hotrolling. Each treatment induced another type of substructure, i.e. tangled dislocations, statically recovered structure, and dynamically recovered structure.Recrystallization behaviour of these three types of substructure-induced specimens was studied by isothermal heat treatments at various temperatures.And, softened width and recrystallized grain diameter at the electron beam weld heat affected zone of substructure-induced plates were compared. Test plates were 100 mm×100 mm square plates of 2 mm thickness.Obtained results were as follows;(1)Annealing at 200°C for 30 min. after cold-rolling gave smaller recrystallized grain diameter and hieher recrvstallization temperature than cold-rolled test specimens.(2)The higher the hot-roing temperaturc, the higher the recrystallization tempcrature became, but slight change of recrystallized grain diaameter was observcd.(3)While hardness of substructure-induced test speciren was below 30, hot-rolled test specimens had higher recrystallization temperature and smaller grain diameter than cold-rolled with or without Q.S.T.specimens.(4)Softened width and grain diameter of electron beam weld heat affected zone of cold-rolled plates were larger than these of cold-rolled with Q.S.T.or hot-rolled plates.