Effect of Thermal Drilling Condition on Burring in Ultrahigh Strengh TRIP Sheet Steels

摘要

Effect of thermal drilling condition on burring of 0.2C-(1.0-2.5)Si-(1.0-2.0)Mn (mass%) ultrahigh strength TRIP-aided sheet steels with polygonal ferrite matrix (TDP steels) was investigated for automotive applications.The combined rotational and downward force of the thermal drilling tool bit created friction heat. The height of the bushing was roughly 3 to 4 times the initial sheet thickness.The bushings are ideal for thread applications,as the strength of threads was significantly increased. We found that the burring and tapping contributed to the improvement of the tensile strength of 980 MPa class TRIP steel.