304不锈钢无缝钢管表面黑白斜条纹的形成机理研究

Formation Mechanism Study of Black and White Diagonal Stripes on Surface of Seamless 304 Stainless Steel Pipes

检测304不锈钢无缝钢管表面黑条纹及白条纹区域的化学成分、金相组织、相结构和粗糙度,并分析研究黑白斜条纹的形成机理。测试结果表明:黑条纹及白条纹区域成分、金相组织及相结构基本相同,均在正常范围内,但白条纹区域粗糙度明显较黑条纹区域大;穿孔导板使用后期对圆钢表面磨损程度不同,使荒管表面粗糙度不同,从而导致成品钢管表面出现黑白斜条纹。适当降低穿孔导板的使用寿命,适时更换新穿孔导板,可杜绝成品钢管表面黑白斜条纹的产生。

The composition, microstructure, phase structure and roughness in the area of the black and white stripes are observed and inspected on the surface of seamless 304 stainless steel pipes and the formation mechanism of the black and white stripes is analyzed. The analysis result shows that the composition, microstructure and phase structure are nearly identical and all within the standard range in the area of either the black or white stripe hut the roughness of the white stripe area is obviously larger than that of the black stripe. The different degree of wear on the guide plate during the later period of hot piercing process causes the different roughness on the shells, which leads to occurrence of the black and white stripes on the surface of finished products. Therefore the occurrence of the black and white stripes on the surface of finished products can be avoided through shortening the working period of the guide plate properly and changing the guide plate with a new one on time.