Comparative analysis of forming performance of 780 MPa grade high strength dual phase steel with different components
The properties of different components of high strength dual phase steel HC420/780 DPD+Z were compared and analyzed.Firstly,on the basis of conventional C-Si-Mn chemical component system,the three kinds of materials with the same strength grade were formed by increasing microalloying elements or changing the original chemical component content.The metallographic structure and me-chanical properties of the three kinds of materials were compared and analyzed.Based on the hydraulic forming experiment machine,the forming limit curves of the three kinds of materials were compared and compared with the three theoretical prediction models.The hole ex-pansion performance and bending performance of the three kinds of materials were compared.Based on AutoForm,the simulation model of the forming process of a car longitudinal beam part was built,and the strain distribution of the three kinds of materials was analyzed.The bending performance verifies whether the material meets the forming requirements of the longitudinal beam.The results show that the mi-crostructure of material with microalloy elements is obviously refined,the martensite presents dispersed and fine state,and the drawing ability of material is enhanced.For material with high carbon component,the contents of C and Cr elements increase,the content of Si el-ement decreases,and there is obvious banded martensite structure,the grain size increases,and the plastic strain ratio r of material in-creases.According to the forming limit curves,it is obtained that the plane major strain of microalloy component material is the maxi-mum,which is about 0.175,and the hole expansion rate is the highest,reaching 26.2%.The 90° bending limit fillet radius is better than the other two kinds of materials,and the cracking risk of longitudinal beam parts is the smallest.The plane major strain of materials with high carbon component is the minimum,which is about 0.133.Conventional component material has the lowest hole expansion rate,only 13.0%and the worst bending performance.Microalloy element material has good comprehensive forming performance of drawing and bending,while high carbon component can obviously improve the bending and hole expansion performance of materials.
万方数据
