Abstract: According to the analysis on outer fold defect of Φ85 mm x 8 mm tube of 37Mn5 steel (0. 39% C, 1. 30% Mn) , it is obtained that the ~ 20 μm brittle inclusions-silicate and SiO2 existing at grain boundary in steel is main reason for formation of tube outer fold. With controlling thickness of top slag ≤50 mm in ladle after LD tapping, (FeO)≤l% , white slag time ≥15 min and soft argon blowing ≥10 min in LF refining, shield casting in whole process, the [ 0 ] is (11. 6 - 17. 1) x 10^-6 and the rating of inclusions in steel of A series is 0 ~ 2. 0，of B and C series is 0 and of D series is 0. 5 ~ 1. 0, that are available to control the formation of outer fold of steel tube.

Key words: 37Mn5 Steel Tube, Outer Fold,, Reason for Formation,, Process Control

摘要： 通过对37Mn5钢(%:0.39C、1.30Mn)Φ85 mm×8 mm管外折叠缺陷的分析,得出钢晶界处存在尺寸～20μm的硅酸盐和SiO2等脆性夹杂物是钢管外折叠形成的主要原因。通过控制转炉出钢后钢包顶渣厚度≤50mm,LF精炼(FeO)≤1%,白渣时间≥15 min,软吹氩≥10 min,全程保护连铸,使[O]为(11.6～17.1)×10^-6,钢中夹杂级别A类为0～2.0,B、C类为0,D类为0.5～1.0,有效地控制钢管外折叠的发生。

关键词: 37Mn5钢管, 外折叠, 成因, 工艺控制