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采用热-力学模拟实验方法研究了X70QS无缝管线钢管在不同冷却速度下的组织演化,并测试典型组织X70QS的力学性能、抗氢致开裂性能、抗硫化物应力开裂性能和动态腐蚀性能。结果表明,当冷却速度小于5℃/s时,X70QS钢的转变组织为PF+P。随冷却速度增大,粒状贝氏体组织的含量不断增加;当冷却速度达到40℃/s时,X70QS钢形成的组织为B粒+PF+P+MA。与组织类型为PF+P+MA的X70QS相比,B粒+PF+P+MA组织具有更好的强韧性。在严格控制带状组织和条状夹杂物形成的条件下,B粒+PF+P+MA组织类型的X70QS具有很好的抗HIC性能和抗SSCC性能。在模拟工况条件下,动态腐蚀速率也较小。
The microstructure evolution of X70QS seamless pipe steel under different cooling rates was studied by means of thermo-mechanical simulation experiment. The mechanical properties, hydrogen-induced cracking resistance, stress-cracking resistance and dynamic corrosion resistance of X70QS were tested. The results show that when the cooling rate is less than 5 ℃ / s, the transformation of X70QS steel is PF + P. As the cooling rate increases, the content of granular bainite increases continuously. When the cooling rate reaches 40 ℃ / s, the microstructure of X70QS steel is B grains + PF + P + MA. Compared with X70QS with PF + P + MA, B + PF + P + MA had better toughness. Under the strict control of the formation of banded and strip inclusions, the X70QS of B grain + PF + P + MA tissue type has good anti-HIC performance and anti-SSCC performance. Under simulated working conditions, the dynamic corrosion rate is also small.