P92无缝钢管裂纹失效分析  

Crack failure analysis of P92 seamless steel pipe

作　　者：刘晓蓉 刘科虹 葛东伟 杨文庆 田光荣 张瑞锋 Liu Xiaorong;Liu Kehong;Ge Dongwei;Yang Wenqing;Tian Guangrong;Zhang Ruifeng(Inner Mongolia Northern Heavy Industry Group Corp.Ltd.,Baotou 014030,China)

机构地区：[1]内蒙古北方重工业集团有限公司,内蒙古自治区包头014030

出　　处：《锻压技术》2025年第3期219-224,共6页Forging & Stamping Technology

摘　　要：采用挤压工艺生产P92无缝钢管过程中,通过对无缝钢管内壁缺陷反射波密集区进行多方面分析,依据宏观检验手段观察到开裂区表面及深度情况,利用断口扫描电镜分析微观断口形貌特征,借助金相检测明确非金属夹杂物、裂纹及基体显微组织特点。分析裂纹产生原因,发现钢管在正火过程中生成大量的δ铁素体相,在受到应力作用时,马氏体组织较脆,细小裂纹极易在塑形较差的δ铁素体处产生。尤其是δ铁素体周围的M_(23)C_(6)碳化物熟化,降低了材料的晶界强度,同时,钢液内聚集形态的颗粒状BN夹杂物导致基体不连续性,进一步加剧了细小裂纹的扩展。因此,坯料在热处理时需将加热温度和时间控制在合理的范围内。In the production of P92 seamless steel pipes by extrusion process,the refection wave intensive area for inner wall defect of seamless steel pipe was analyzed in many aspects,and based on macroscopic inspection,the surface and depth of the cracking areas were observed.Then,the microscopic fracture morphology characteristics were mastered by fracture scanning electron microscope analysis,and the non-metallic inclusions,cracks and matrix microstructure characteristics were clarified by metallographic inspection.Furthermore,the causes of cracks were analyzed,and it was found that a large amount ofδ-ferrite phase was generated in the steel pipe during the normalizing process.When subjected to stress,the martensitic structure was brittle,and small cracks were easily generated in theδ-ferrite with poor plasticity.In particular,the ripening of M_(23)C_(6)carbide aroundδ-ferrite reduced the grain boundary strength of the material.At the same time,the granular BN inclusions in the form of aggregates in the molten steel led to matrix discontinuity,which further aggravated the expansion of small cracks.Therefore,the heating temperature and time of the billet should to be controlled within a reasonable range during heat treatment.

关 键 词：P92无缝钢管 裂纹 Δ铁素体 氧化 BN夹杂物 

分 类 号：TG142.1[一般工业技术—材料科学与工程]