模具钢4Cr5MoSiVl超声探伤缺陷的分析和工艺改进

山钢特钢事业部新区采用铁水+废钢→100 t电弧炉→双工位LF→双工位VD→圆坯连铸(Φ500 mm断面)→步进式加热炉→950轧机轧制的流程生产模具钢4Cr5MoSiV1,个别批次的4Cr5MoSiV1模具钢存在探伤不合格缺陷,通过对该批次探伤不合格缺陷部位运用超声波进行定位,对所取试样进行金相和扫描电镜分析,最终确认了铸坯的心部缺陷及轧制压缩比小,是造成该批次4Cr5MoSiV1钢探伤不合格的主要原因,并提出了相应的改进措施。

Cause Analysis on Defect of Die Steel 4Cr5MoSiVl by Ultrasonic Detection and Process Improvement

The die steel 4Cr5MoSiV1 was produced with the path of hot metal + scrap→100 t EAF→double LF→ double VD→ round billet continuous casting (section Φ 500 mm)→ step reheating furnace→ 950 rolling mill,in the special steel division new district of Shandong Steel. There are defects in the detection of individual batches die steel 4Cr5MoSiV1. By using the ultrasonic testing to locate the defect location, and analyzing with the way of Metallographic analysis and scanning electron microscopy (SEM) , finally confirmed the center defect and the rolling compression ratio small are the main reasons of the testing substandard batch of steel 4Cr5MoSiV1, and the corresponding improved measures are put forward.