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利用常规力学性能测试设备和透射电镜研究了不同回火温度对一种高强度X120管线钢的显微组织与力学性能的影响。结果表明,试验钢经回火处理后板条间M/A膜明显弱化,贝氏体板条出现粗化和合并,板条间界呈锯齿状发展,原有析出相长大并有含Nb第二相进一步析出;随着回火温度的升高,试验钢中的贝氏体板条宽度增大,小角度晶界所占比例增加。热轧态试验钢的力学性能优良:R eL=920 MPa,R m=1100 MPa,A=13.0%,KV2(-20℃)=227 J;但是随着回火温度从450℃升高到610℃,材料的屈服强度从910 MPa增大至970 MPa;冲击吸收能量(-20℃)从213 J降至173 J;抗拉强度在1010 MPa和982 MPa之间波动,530℃回火时最小。
The effects of different tempering temperatures on the microstructure and mechanical properties of a high-strength X120 pipeline steel were investigated using conventional mechanical properties testing equipment and transmission electron microscopy. The results show that the M / A film of the slab after tempering is obviously weakened, the bainite slab appears coarsening and merging, and the slab boundary develops in a jagged pattern. The original precipitated phase grows and contains Nb The second phase further precipitation; with the tempering temperature increases, the test steel bainite lath width increases, the proportion of small-angle grain boundaries increased. The mechanical properties of the hot-rolled steel are excellent: R eL = 920 MPa, R m = 1100 MPa, A = 13.0%, KV2 (-20 ℃) = 227 J; however, as the tempering temperature increases from 450 ℃ to 610 ℃, the yield strength of the material increased from 910 MPa to 970 MPa; the impact absorption energy (-20 ℃) decreased from 213 J to 173 J; the tensile strength fluctuated between 1010 MPa and 982 MPa, .