钢管表面铜金属污染的危害性分析

天然气输气管线钢管的母材在现场检测时发现硬度不合格现象，通过宏观观察、电镜扫描、金相分析及微观硬度测试等多种检测方法确定钢管表面有铜金属污染存在。铜金属污染实质上属于异金属夹杂，产生的原因是冶炼操作不当，合金料未完全熔化或浇注系统中掉入异金属。该异金属夹杂物由于与基体的组织、性能均不同，与基体组织有明显的界限，会割裂基体的连续性，降低材料的力学性能，在受力过程中成为应力集中点从而降低钢管的使用寿命。

Hazard analysis of copper metal pollution on surface of steel pipe

The unqualified hardness was observed during the field test of base metal of steel pipe for natural gas transmission. Through macroscopic observation, scanning electron microscopy (SEM), metallographic analysis, and microhardness test, it was found that there was copper metal pollution on the surface of steel pipe. Copper metal pollution was essentially belonged to heterometallic inclusion, which was caused by improper smelting operation, incomplete melting of alloy material or falling of foreign metal into gating system. Because the structure and properties of such dissimilar metal inclusions were different from the matrix, there were obvious boundaries with the matrix structure, which would split the continuity of the matrix and reduce the mechanical properties of the material. It would become the stress concentration point in the process of stress, and consequently reduce the service life of the steel pipe.