1000MPa级双相钢弯曲性能试验

弯曲性能是衡量汽车用超高强钢板冲压成形的重要指标。通过14种典型DP980CR和DP980GI超高强钢板的弯曲极限试验,深入分析1000MPa级超高强钢板的弯曲极限Rmin/t,并研究了各向异性和剪切质量对弯曲极限的影响规律。研究结果表明,宝钢1000MPa级超高强DP钢的弯曲极限与进口材相近,DP980CR的Rmin/t约为2,DP980GI的Rmin/t约为2.2。超高强DP钢的弯曲极限与延伸率间无相关性,这与经典塑性理论有所不同。各向异性对超高强钢板相对弯曲半径影响显著,0°方向的相对弯曲半径明显高于90°方向试样,进口材料和宝钢材料均如此。边部质量对超高强钢板弯曲极限影响显著,冲裁后弯曲极限比铣削状态降低,而毛刺带位于弯曲外侧,进一步降低弯曲极限,Rmin/t达到3.6。

Experimental study on bending properties of 1000MPa DP steel

Bending property is one of the key parameters to evaluate the formability of UHSS(Utra High Strength Steel).In this paper,bending tests of 14 kinds of DP cold rolled steel and hot-dip coated steel were carried out and relative limit bending-radius Rmin/t of 1000MPa class DP steel and its influence factors were experimentally studied.The results showed that Rmin/t of Baosteel DP980CR was about 2.0 and DP980GI was about 2.2,which was close to the imported steels.Different from plastic forming theory,Rmin/t of UHSS does not have relationship with elongation.Anisotropy has great influence on UHSS's bendability and limit bending radius along rolling direction is obviously greater than that perpendicular to rolling direction.Besides,limit bending radius of UHSS is greatly influenced by the edge quality of specimens.Specimens with cutting edge has lower limit bending radius than those with milling edge.Moreover,specimens with edge burr on out-side of bend is worst,which Rmin/t is about 3.6.