X70管线钢热煨弯管的外弧裂纹分析
Cracking Analysis on the External Arc of Induction Heat Bend X70 Steel Pipe
霍向东,，郭林，黎剑锋，黄克坚
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作者单位：江苏大学材料学院,江苏大学材料学院,番禺珠江钢管有限公司，番禺珠江钢管有限公司
中文关键字：弯管; 裂纹; 氧化; 自由能
英文关键字：bend pipe; cracks ; oxidation; free energy
中文摘要：采用光学显微镜、扫描电镜和X-射线能谱仪，对热煨弯管过程中在外弧拉伸区出现的横向裂纹进行了研究。管线钢具有针状铁素体(AF)和粒状贝氏体(GB)组织，弯管工艺对弯曲段整体和局部的力学性能无明显影响；铸坯加热过程中Cu的富集弱化晶界强度，弯管过程中外弧拉伸区产生最大的拉伸应变，一起导致了裂纹产生。
英文摘要：Experimental methods, such as OM, SEM and X-EDS, were used to study the transverse cracks appeared on the external arc of tensile region during pipe bending. The pipe line steel consists of acicular ferrite (AF) and granular bainite (GB), and bending process has no obvious influence on mechanical properties of whole or local bending segment. Copper phase enrichment during slab reheating weakens grain boundaries, and maximal tensile strain occurs on the external arc of tensile region during pipe bending. They both induce the cracks.