百米高速重轨钢中大型MnS夹杂的形成原因

大型MnS是引起百米高速重轨夹杂物超标和超声波探伤不合的重要原因.理论计算表明,对于U75V重轨钢,在凝固末期固相分率大于0.98时,MnS才能在液相中析出.利用扫描电镜配合能谱仪分别对铸坯和钢轨试样中Mns夹杂进行了研究.结果表明,铸坯边部是尺寸小于10 μm的球状MnS,中心为尺寸小于30 μm扇形或条状MnS,钢...

Formation reason of large MnS in hectometer high speed heavy rail steel

The existence of large MnS is an important reason to cause the inclusion overproof and nonconformity in ultrasonic flaw detection.Theoretical calculation for U75V steel shows that MnS inclusion is formed in the liquid steel at final period of solidification when the solidification fraction is greater than 0.98.MnS inclusion in casting slab and heavy rail were examined by SEM and EDX.The results showed that MnS were globular with the size less than 10 μm in the border and sector or banding with the size less than 30 μm in the centre of the casting slab;the size of single MnS was less than 100 μm in the head part of heavy rail and less than 400 μm in the waist part of heavy rail.It is concluded that large MnS distributed in gathering form induces the inclusion overproof and nonconformity in ultrasonic flaw detection rather than those distributed in single form.