某公司生产的718H钢和40Cr13钢在低倍检验时发现有严重疏松。通过化学成分分析、低倍检验、夹杂物检验、金相检验等方法，分析了718H钢和40Cr13钢中心疏松缺陷的形成原因。结果表明：718H钢产生疏松缺陷的主要原因是夹杂物聚集；40Cr13钢产生疏松的主要原因是易偏析溶质元素的析出与聚集；最后根据疏松缺陷的产生原因提出了具体的改进措施。

Severe porosity was found in 718H steel and 40Cr13 steel produced by some company. The forming reasons of center porosity of 718H steel and 40Cr13 steel were analyzed through methods of chemical composition analysis, macroscopic examination, inclusion examination, metallographic examination, etc. The results show that:the main reason for porosity of 718H steel was agglomeration of inclusions; the main reasons for porosity of 40Cr13 steel were precipitation and agglomeration of segregation solute elements; finally specific improvement measures were also put forward according to the porosity reasons.