φ177.80 mm×10.36 mm P110无缝管坯裂纹缺陷分析及预防

Defect analysis and prevention of cracking in φ177.80 mm×10.36 mm P110 seamless pipe billet

牌号30MnCr22φ177.80 mm×10.36 mm管坯热处理升钢级后转变成P110钢级管坯,后续无损检测时发现该管坯表面存在裂纹,通过将该裂纹取样进行宏观断口分析、金相分析、断口扫描分析和能谱分析,确定出该裂纹的性质及产生原因是管坯原材料中含有Ti、O、Si、Al等元素,钢坯冶炼不够纯净,在热处理淬火过程中应力过大所致,诱发产生淬火裂纹,在后续生产时从钢坯冶炼、热处理淬火温度选取及钢管冷却温度控制等几个方面予以优化,避免此类裂纹缺陷的产生,达到工艺优化、消除缺陷的目的。

Brand 30 MnCr22 φ177.80 mm×10.36 mm steel tube blank was converted to P110 steel tube billet after upgrading by heat treatment. Some cracks were observed on the surface of tube billet in the subsequent nondestructive testing. The crack was sampled for macro-fracture analysis, metallographic analysis, fracture scanning analysis and energy spectrum analysis. The property of cracks was determined. It was found that the raw materials of tube billet contained Ti, O, Si and Al. The smelting of steel billet was not pure enough. The stress in the quenching process of heat treatment was too large to induce the formation of quenching cracks. In the process of subsequent production, the formation of such crack defects could be avoided by optimizing the steel billet smelting, selection of quenching temperature in heat treatment as well as control of cooling temperature for steel tube. Therefore, the aims to optimize process and eliminate defect could be achieved.