16Mn钢空心锻件探伤缺陷形成原因分析及工艺改进

Cause Analysis and Process Improvement of Defects of 16Mn Steel Hollow Forgings

对执行电炉(EBT)+钢包精炼(LF)+真空脱气(VD)+真空浇注(VC)双真空工艺路线生产的16Mn钢空心锻件进行了探伤,发现锻件(对应钢锭水口端)存在缺陷。对缺陷试样进行了宏观断口分析、扫描电镜观察及能谱分析。结果表明:筒体锻件缺陷是由大尺寸夹杂物导致的,缺陷处夹杂物主要成分为MnO-SiO_(2)-Al_(2)O_(3)-CaO、Al_(2)O_(3)-MgO-ZrO_(2)-CaO和SiO_(2)-Al_(2)O_(3)-ZrO_(2)。其中MnO-SiO_(2)-Al_(2)O_(3)-CaO和Al_(2)O_(3)-MgO-ZrO_(2)-CaO是脱氧过程和精炼合金化过程形成的,SiO_(2)-Al_(2)O_(3)-ZrO_(2)形成于浇注过程的导流管内壁冲刷,凝固过程该类夹杂物进一步聚集、合并、长大。基于以上分析提出了工艺改进措施,采用改进措施生产的锻件,探伤质量问题得到有效改善。

The flaw detection of 16Mn steel hollow forgings produced by the double vacuum process line of EBT+LF+VD+VC was carried out,and defects in forgings (corresponding to steel ingot nozzle end) were found.Macroscopic fracture analysis,SEM observation and energy spectrum analysis were carried out.The results show that the defects in cylinder forgings are caused by large inclusions,the main components of inclusions in defects are MnO-SiO_(2)-Al_(2)O_(3)-CaO,Al_(2)O_(3)-MgO-ZrO_(2)-CaO and SiO_(2)-Al_(2)O_(3)-ZrO_(2).And MnO-SiO_(2)-Al_(2)O_(3)-CaO and Al_(2)O_(3)-MgO-ZrO_(2)-CaO are formed in deoxidation process and refining alloying process.SiO_(2)-Al_(2)O_(3)-ZrO_(2) is formed by the honeycomb duct scour of the inner wall in the pouring process,the inclusions are further aggregated,merged and grown during solidification.Based on the above analysis,the process improvement measures were put forward,and the quality problems of flaw detection were effectively improved.