L450M管线钢管母材开裂原因及预防措施

为了研究L450M管线钢制管过程中机械扩径后母材开裂的原因，通过对断口进行宏观观察、微观分析以及钢板探伤，分析了管体机械扩径后母材开裂情况。结果显示，管体机械扩径后母材开裂部位以铁素体组织为主，含极少量的C元素，且并无其他元素成分。经分析，确定管体开裂是由于在连铸时冷钢掉入结晶器内未完全熔化、包裹在板坯内，经轧制而形成缺陷，最终导致管体开裂。

Cracking Causes and Preventive Measures of Base Metal of L450M Steel Pipe

In order to find out the causes of the cracking of the base metal after the mechanical expansion of the L450M pipe, through macro analysis, microscopic analysis and plate flaw detection of the cracked fracture, the cracking of the base metal is analyzed of after the mechanical expansion of the line pipe body. The results show that the cracked part of the base metal of the line pipe body after mechanical expansion is mainly ferrite, containing a very small amount of C element, and no other element components. It is determined that the pipe body cracking is due to the defects formed by the cold steel falling into the mold, incomplete melting and wrapping in the slab during continuous casting, and finally leading to the pipe body cracking.