The Influence Of Hot-forming Technology On The Properties Of High Strength Steel

With the rapid development of automotive industry, the newappeal of safety, environmental protection and energy-efficient has beenproposed in automotive field, the emergence of high strength steel makethe call coming true. Hot forming technology is a new technique whichcombines traditional thermal forging manufacturing technology and coldstamping skill in recent years. That produce motor vehicle structuralcomponents using high strength steel not only satisfy safety andcapability of crash, but also lighten the weight of car body, theseperformance reach the goal of energy conservation and emissionsreduction. High strength steel hot forming technique has broad market,so the insiders pay close attention to this technology.The technological parameters have great influence on sheetproperties after hot forming. This article in hot forming process affectthe performance of high strength steel as the theme, with high strengthsteel22MnB5boron as the research object, studied the variation of sheetmechanical property and microstructure in different heating temperature.Finally, it had been improved that900℃was the optimal heatingtemperature. Besides, the austenite grain size using grain boundarycorrosion method was more accuracy than using oxidation method. Onthis basis, sheet was been heated for900℃and keep warm for3minusing electrical heating method, then stretched at strain rate of0.1s-1、 0.01s-1、0.001s-1in different forming temperature900℃,800℃,700℃,600℃,500℃. After analysing date it gained the true stress-true straincurve, and strain hardening exponent N. The result had obtained thatsheet formability was better forming above600℃. With formingtemperature reducing, the stress increased at the same strain rate. Inorder to gain optimal technical parameters, the three factors of heatingtemperature, soaking time and forming temperature were considered.Designing orthogonal experiment optimized technical parameters. Theresult obtained the influence orders of sheet different performance on theimpact of three factors. Also gained the optimal parameters group:heating temperature900℃, soaking time5min,forming temperature700℃，and sheet had good formability in this working condition.