【摘要】 通过热模拟实验研究了不同变形温度和终冷温度工艺对X70M管线钢显微组织和硬度的影响。结果表明:奥氏体非再结晶区的大变形和变形后快速冷却有助于针状铁素体的形成。经生产验证,采用含有0.065%Nb和0.20%Cr的较为简单的化学成分设计,X70M可以获得屈服强度均值537 MPa、抗拉强度均值663 MPa和-60℃夏比V型冲击功最小值380 J的强韧性能。低屈强比的X70M高强韧性的主要机制在于晶粒细化。当减小碳含量至0.065%以下并且增加针状铁素体的比例,可以将钢管和板卷之间屈服强度的变化控制在约10 MPa水平。更多还原

【Abstract】 Effect of different deformation and cooling processes on microstructure and hardness of low yield strength ratio X70 M steel was investigated by thermal simulation experiment. The results show that both faster cooling and larger deformation process below the nonrecrystallization temperature are helpful to produce acicular ferrite. The industrial production results indicate that the yield strength of X70 M steel with 0. 065% Nb and 0. 20% Cr content is about 537 MPa,and the tensile strength is about 663 MPa,the impact absorbed energy at minus 60 ℃ is greater than 380 J. The higher strength and toughness mechanism of the X70 M steel is grain refinement. When minimize the carbon content lower than 0. 065% and increases the fraction of acicular ferrite,the reduction in yield strength between steel coil and pipe can be controlled within about 10 MPa.更多还原