厚规格718H模具钢探伤不合格原因分析及控制

厚规格718H模具钢在超声波探伤时发现在厚度1/2位置出现探伤不合格的情况,对其进行了低倍检验、光学显微镜检验、扫描电镜观察和能谱分析。结果表明,探伤不合的主要原因是连铸坯中心疏松和中心偏析缺陷,没有轧合、消除或改善,从而遗留到钢板厚度中心区域造成。针对以上原因,采取了一系列冶炼、轧制措施,钢板探伤合格率明显提高,100 mm及以上厚度钢板探伤合格率由96.18%提高到99.16%。

Analysis and control of flaw detection unqualified reasons for die steel 718H of thick specifications

During ultrasonic flaw detection of die steel 718H with thick specifications, the disqualification at 1/2 of the thickness of the die steel was found. Inspected by macroscopic examination, optical microscope, SEM and energy spectrum, the results show that the main reasons for the defects are loose center and segregation defects of continuous casting billet, which are left in the central area of steel plate thickness without rolling, eliminating or improving. According to the above reasons, a series of control measures of smelting and rolling were adopted, and the pass rate of steel plate flaw detection was significantly increased, from 96.18% to 99.16% for steel plate with thickness of 100 mm and above. Key words: flaw detection; segregation; loose center; rolling; free surface of metal