由于高级管线钢要求较低的碳含量,因此通常靠提高锰含量来保证其强度。锰还可以推迟铁素体→珠光体的转变,并降低贝氏体的转变温度,有利于形成细晶粒组织。但锰含量过高会对管线钢的焊接性能造成不利影响。当锰含量超过1.5%时,管线钢铸坯会发生锰的偏析,且随着碳含量的增加,这种偏析更显著。锰对于X40~X70级,厚度为16~25mm管线钢抗HIC性能也有影响,主要分为三种情况:含 Because of the lower carbon content of advanced pipeline steels, the strength is usually guaranteed by increasing the manganese content. Manganese can also delay the ferrite → pearlite transformation, and reduce the bainite transformation temperature, is conducive to the formation of fine grain structure. However, the high manganese content will adversely affect the weldability of pipeline steel. When the manganese content exceeds 1.5%, segregation of manganese occurs in the pipeline steel slab, and this segregation becomes more significant as the carbon content increases. Manganese for X40 ~ X70 grade, the thickness of 16 ~ 25mm HIC pipeline steel also has an impact on performance, mainly divided into three cases: with