非调质N80油井管钢的典型组织缺陷分析及其影响

Analysis of and Influence by Typical Structural Defects of N80 Non-quenched and Tempered Steel for OCTG-making

通过对非调质N80油井管钢的金相组织研究,分析了该钢典型组织缺陷的产生原因及其对力学性能的影响。结果表明,国内使用的非调质N80油井管钢的典型组织为P+F和B+P+F;组织缺陷主要为粗大网状铁素体、片状马氏体组织、过热魏氏组织以及表面脱碳,会使钢材的韧性降低;片状马氏体组织对钢材的使用性能危害最为严重,会使钢材的冲击韧性显著降低,是钢材发生应力腐蚀及断裂的直接原因。

Based on the study of the metallographic structure of the non-quenched and tempered N80 OCTG -purpose steel, an analysis is made to identify the causes responsible for development of typical structural defects of the steel and the influence by such defects on the mechanical properties thereof. The analytical result shows that the typical structures of the domestically-used non-quenched and tempered N80 OCTG-purpose steel are P＋F and B＋P＋F. Relevant main structural defects are course network ferrite, flake martensitic structure, overheated Widmannst？tten structure and surface decarbonization, which reduce toughness of the steel, particularly the flake martensitic structure that is most harmful to operation properties of-the steel, and significantly reduces the steel＇ s impact toughness, being the direct cause for stress corrosion and rupture of the steel.