摘要
通过力学性能测试和微观组织分析,研究了回火温度对低碳贝氏体X80管线钢组织及低温冲击韧性的影响。结果表明,低碳贝氏体X80管线钢在300℃回火2 h后达到最佳强韧性匹配,屈服强度在625 MPa,-40℃夏比冲击功为315 J,冲击断口呈现明显的韧性断裂形貌,-60℃夏比冲击功也达到了268 J。低碳贝氏体管线钢轧态组织以粒状贝氏体为主,经过300℃回火2 h后,组织与TMCP状态基本相似,仍保持粒状贝氏体组织,但是MA组元略细小;经过600℃回火2 h后,贝氏体出现粗化,并且出现多边形铁素体组织。低温韧性的改善是由于回火处理过程中富碳残留奥氏体发生转变,M/A组元由岛状转变为点状及细条状,粒状贝氏体晶间细化的M/A组元更好的阻碍了裂纹的扩展。
Effect of tempering temperature on low temperature toughness and microstructure of low carbon bainitic X80 pipeline steel was studied by mechanical properties test and microstructure analysis.The results indicate that the strength and low temperature toughness have the best matching at 300 ℃tempering for X80 low carbon bainitic pipeline steel.The YS ( yield strength) remains at 625 MPa.The charpy absorbed energy at -40 ℃reaches 315 J and 268 J at -60 ℃.TMCP process produced low carbon pipeline steel is mainly GB ( granular bainite) structure.The microstructure remains the same with the as rolled state after tempered at 300 ℃for 2 h.The GB starts to coarsing and some PF ( polygon ferrite) starts to appear in the microstructure after tempered at 600℃.The low temperature toughness improvement is due to the transform of M/A components at the grain boundary from islands to spots and strips in the process of tempering.All these microstructure can inhibit the propagation of the crack.
出处
《金属热处理》
CAS
CSCD
北大核心
2014年第10期108-112,共5页
Heat Treatment of Metals
关键词
X80管线钢
低碳贝氏体
回火组织
低温韧性
X80 pipeline steel
low carbon bainitic steel
tempering microstructure
low temperature toughness
