Mechanism of Internal Surface Crack Formation of Seamless Modified 9Cr-1Mo Steel Tube Rolled by Mandrel Mill and Its Application
The hot workability of modified 9Cr- 1Mo, as a grade of heat resistant steels, is inferior to that of low-alloy steel,so the inner surface crack (ISC) easily occurs in seamless boiler tubes produced by the Mandrel Mill under improper rolling conditions. With the aid of FEM, the metal flow status during the rolling process was analyzed in 140mm 8-stand mandrel mill of Bao Steel. Both the metallographic shape and size of the ISC together with the result from the simulation show that the ISC of seamless tube forms at the elongation stage of shell. The mechanism of the ISC was discussed. With its initiation in stand No.1 and No.2 due to poor hot workability of modified 9Cr-1Mo steel, the ISC develops in subsequent passes.Based upon the mechanism devised was a special roll pass system which substantially upgraded the yield of qualified products.
seamless tube T91 mandrel mill defect crack mechanism roll pass
LI Sheng-zhi XU Jie YIN Yuan-de XUE Jian-guo FENG Yuan
Department of Materials Forming and Control Engineering, Anhui University of Technology, Maanshan 24 Department of Materials Forming and Control Engineering, Anhui University of Technology, Maanshan 24 Steel Tube & Pipe Company of Bao Steel Co., Ltd, Shanghai 200941, China
国际会议
北京
英文
273-276
2007-09-18（万方平台首次上网日期，不代表论文的发表时间）