抄録
Effect of two step aging and cold rolling treatment on the hardness of Ti-15V-3Cr-3Sn-3Al alloy and its welds. Two step aging treatment was made by a process aged at 673 K for various times and aged at 773 K for 86.4 ks after solution treatment. The cold rolling treatment was made by a process solution-treated, 20% or 50% cold rolled and aged at 673 K for various times.
The two step aging treatment accelerated the precipitation of alpha phase, increased the volume fraction of alpha phase and increased the age hardening in both specimens solution-treated at 1573 K and 1073 K.
As the aging time at first step 673 K was up to 100 ks, fine alpha phase was observed, the duplex microstructure consisting of fine alpha phase and corse alpha phase was observed above the time.
The cold rolling treatment accelerated the precipitation of alpha phase in 1073 K solution treatment. The microstructure after aging showed fine spherical precipitates of alpha phase by cold rolling treatment.
The two step aging treatment and the cold rolling treatment caused the hardness increase in not only the base metal but also the weld heat affected zone.
