Springback and hardness of aluminum alloy sheet part manufactured by warm forming process using non-isothermal dies

Abstract

Abstract Generally, aluminum alloy sheet parts manufactured through hot forming still need to undergo heat treatment before meeting performance requirements. Nevertheless, warm forming parts have performances equivalent to cold forming parts, while the blank heating during warm forming is carried out before forming, which leads to longer processing time and lower efficiency. In this paper, a warm forming process using dies to apply force and heat the blank simultaneously was studied. A series of warm bending experiments called non-isothermal bending employing tool temperatures ranging from 25 °C to 400 °C were carried out to obtain the influence of temperature on springback and hardness of sheet parts. Meanwhile, isothermal bending experiments at 200 °C and 300 °C were carried out for comparison in which the temperatures of blank and dies were kept the same. The results showed that the springback of non-isothermal bending parts is about 10% less than that of isothermal bending parts when the blank temperature is the same during bending. Moreover, the hardness of non-isothermal bending parts is maintained above 150 HV while that of isothermal bending parts is only 132.8 HV at 200 °C and 115.1 HV at 300 °C. Thus, it is indicated that the warm forming process using high temperature dies to heat and bend the blank simultaneously can achieve good forming accuracy and favorable part performance, with no need for successive heat treatment.