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在实验室条件下对热轧X120管线钢进行两种不同工艺淬火,研究了回火温度对不同淬火态试验钢组织力学性能的影响。试验结果表明:直接快冷工艺下,显微组织以板条铁素体+马氏体为主;缓冷+直接快冷工艺下以粒状贝氏体+板条铁素体+马氏体为主。随回火温度升高,两种试验钢强度均出现起伏,在400~500℃范围内回火后,冲击功和伸长率均得到改善;采用直接快冷工艺在350℃和600℃回火后出现断口分离现象,从而导致力学性能波动,而缓冷+快冷工艺在回火过程中力学性能稳定性较好。因此,采用缓冷+快冷工艺+(450~500℃)回火,其力学性能达到X120级管线钢性能要求。
Under different laboratory conditions, the hot rolling of X120 pipeline steel was quenched by two different techniques. The effect of tempering temperature on the microstructure and mechanical properties of different quenched test steels was studied. The results show that the microstructure is dominated by lath ferrite and martensite under the direct fast cooling process, while the granular bainite + lath ferrite and martensite are the Lord. With the increase of tempering temperature, the strength of both tested steels fluctuated. After tempering in the range of 400-500 ℃, both the impact energy and elongation were improved. After direct tempering at 350 ℃ and 600 ℃ Fracture separation appears, resulting in mechanical properties fluctuations, and slow cooling + fast cooling process in the tempering process better mechanical properties. Therefore, the use of slow cooling + fast cooling process (450 ~ 500 ℃) tempering, the mechanical properties of X120 to achieve pipeline performance requirements.