GB1979-80结构钢低倍组织缺陷评级图是检验的依据。但在实际生产中常出现一些标准未涉及到的现象。40Mn2氧气瓶钢热酸腐蚀时就出现过异常现象,对这种现象应如何评价呢?我们针对一批40Mn2钢坯酸蚀试验中出现的所谓黑、白两色区域(图1)进行了分析、鉴定。金相观察表明,黑、白两区的组织不同(图2)。白区组织为片状珠光体和呈网络块状的铁素体,黑色区为点状和球状珠光体,即典型的退火珠光体。将试样经840℃ GB1979-80 low magnification structural steel structural defect rating map is the basis for testing. However, some phenomena that are not covered by the standards often appear in actual production. 40Mn2 oxygen tank hot acid corrosion appeared abnormal phenomenon, how to evaluate this phenomenon? We for a group of 40Mn2 billet acid corrosion test appears in the so-called black and white areas (Figure 1) were analyzed, Identification. Metallographic observation shows that the black and white districts are different (Figure 2). The white zone is organized into lamellar pearlite and network massive ferrite. The black zone is spot-shaped and spherical pearlite, which is typical annealed pearlite. The sample by 840 ℃