Effects of Stress Relieving on Limit Dome Height of Titanium Tailor-Welded Blanks at Elevated Temperatures

Abstract

This paper aims to study the effect of stress relieving on Limit Dome Height (LDH) of Ti-TWBs at elevated temperatures. This is achieved by developing a newly constructed heating system. The elevated temperature of the system can be varied and monitored by a separately control panel. All Ti-TWBs were prepared and used to examine the LDHs under elevated temperatures. Selected specimens were heat-treated at 600°C within an hour before being formed by HILLE machine. Meanwhile, the temperature of tool heating system was also adjusted from room temperature to 550°C. Specified tests were carried out to examine the stress relieving effects of Ti-TWBs on the LDHs with the temperature control panel. In addition, investigations were carried out to ascertain whether the elevated temperatures of the critical tooling components, i.e. the die and the blank holder, could result in any significant effects on LDHs of Ti-TWBs. The findings show that LDHs of Ti-TWBs can be improved by stress relieving. The stress relieving condition can be obtained by nearly isothermal forming of specimens at a range of 550°C to 600°C.

Thermal forming of light-weight alloys under a multi-stage forming process

“…2 and Table 3, respectively. All specimens were stress-relieved at 650 • C in a furnace for 30 min followed by room cooling [23] in order to eliminate the residual stresses that may be developed during the machining process [24].…”

Effects of tooling temperatures on formability of titanium TWBs at elevated temperatures

“…In reality, undesirable stresses often occur during welding process. The residual stresses [4] inside the weldment could affect the forming behavior of the qualified specimen (refer to EN ISO 15614-11 [5]). Therefore, prior heat-treatment for stress relieving should be used to enhance the drawability of Ti-TWBs.…”

Warm-Forming of Light-Weight Alloys under Multi-Stage Forming Process

“…The size of specimen were prepared and scaled-downed in accordance with the standard ASTM E8 [10]. All specimens were stress-relieved [11] in order to eliminate the residual stresses that may be developed during the machining process [12].…”