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以热处理后的建筑用X90级第三代管线钢为研究对象,分析了热处理对其组织和力学性能的影响。结果表明,经热处理后试验钢组织由板条和粒状贝氏体、M/A以及准多边形的铁素体的多相组织构成。低密度的准多边形铁素体能够提高钢基体的韧性;含Nb析出物可抑制位错的滑移;夹杂在位错之中的极硬M/A可以提高钢的强度。经热处理后,试验钢具有较低的屈强比,较高的延展性能,能有效减少裂纹和开裂的产生,提高材料的安全性能。
Taking the third generation of X90 grade pipeline steel for heat treatment, the effects of heat treatment on its microstructure and mechanical properties were analyzed. The results show that after heat treatment, the microstructure of the test steel is composed of laths and granular bainite, M / A and multi-phase ferrite structure of quasi-polygon. Low-density quasi-polygonal ferrite can improve the toughness of the steel matrix; Nb-containing precipitates can inhibit the dislocation slip; inclusion in the dislocations among the extremely hard M / A can improve the strength of the steel. After heat treatment, the test steel has a lower yield ratio, higher ductility, can effectively reduce the cracks and cracking, improve the safety performance of the material.