CB80高强度耐低温管线管热处理工艺研究

摘要

以淬火硬度、金相组织和晶粒度为评价尺度,确定CB80管线管的最佳热处理制度;利用透射电镜及EDS, 对CB80管线管第二相粒子的形貌及成分进行分析.分析认为:淬火温度为1 020℃,回火温度在560～580℃时,CB80管线管的性能满足API Spec 5L-2012标准对X80QO钢级的要求,且具备较高的低温冲击性能;Nb、V、Ti在1 020℃时能充分溶解于奥氏体中,并在回火过程中析出,从而起到强化作用,提升钢管性能;调质态下的CB80管线管中析出物主要为NbC和少量的TiN; CB80调质样管的微观组织主要由回火马氏体板条以及析出物构成,回火后马氏体中的碳化物较少,位错密度不高.%The optimum heat treatment procedure for a CB80 linepipe is determined by evaluating its quenching hardness, microstructure and grain size.The analysis shows that when the quenching temperature is 1 020℃ and the tempering temperature ranges in 560～580℃, the performance of a CB80 linepipe will meet the requirements of API Spec 5L-2012 for X80QO steel grade, and it will have pretty good low-temperature impact properties.Nb, V and Ti can fully dissolve in austenites at 1 020 ℃ and precipitate during tempering, which will strengthen and improve the performance of a pipe.The precipitates in a quenched and tempered CB80 linepine are mainly NbC and a small amount of TiN.The microstructure of a quenched and tempered CB80 sample is mainly composed by tempered lath martensites and precipitates.After tempering, the martensite will show fewer carbides and less dislocation density.