A kind of the hot rolled large H-beam steel with low CSiMnCuNi alloy system bearing Nb was designed.Based on the production process of the hot-rolled large H-beam steel,the effects of rolling temperature,reduction rate,and cooling method on the microstructure and mechanical properties of large H-beam steel were explored.The results show that the microstructure consisting on coarse granular bainite with M/A island size of about 3-5μm,a small amount of ferrite with grain size of 10-15μm,lath bainite and the mechanical property with the yield strength of 531 MPa are obtained from thick gauge and large H-beam steel under air cooling condition.Furthermore,the impact energy shows a steep decline trend with the experimental temperature and the impact energy is only 40 J at-40℃.However,the microstructure consisting on fine lath bainite,granular bainite with distributing M/A island like dotting shape,a small amount of ferrite with grain size of 6-10 μm and the mechanical property with the yield strength of 662 MPa are obtained from thick gauge and large H-beam steel under water cooling condition.In correspondingly,the impact energy slowly decreases with temperature and the impact energy is 194 J at-40℃.The thinner specifications large H-beam steel with a large reduction ratio show a more fine-granular bainitic,ferrite microstructure and a more excellent comprehensive mechanical property with yield strength of 625 MPa.Also,the impact energy is almost in a level straight line with the experimental temperature,and reaches 262 J at-40℃.
large-size H-beam steelbainitehigh strength and toughnessmicroalloyingrolling process
维普
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