Effect of Nb on Mechanical Properties of HAZ for High-Nb X80 Pipeline Steels

• Published in: Journal of iron and steel research, international international, 2013-12, Vol.20 (12), p.53-60
• Main Authors: CHEN, Xiao-wei, LIAO, Bo, QIAO, Gui-ying, GU, Yu, WANG, Xu, XIAO, Fu-ren
• Format: Article
• Language: English
• Subjects: Alloy plating; Alloy steels; Alloying elements; Applied and Technical Physics; CGHAZ; Engineering; HAZ; Heat affected zone; High strength low alloy steels; high-Nb X80 grade pipeline steel; Iron and steel industry; Machines; Manufacturing; Materials Engineering; Materials Science; mechanical property; Metallic Materials; microstructure; Niobium; Physical Chemistry; Processes; Steels; welding thermal cycle; X80管线钢; 力学性能; 合金元素; 热模拟机; 粗晶热影响区; 铌
• ISSN: 1006-706X; 2210-3988
• DOI: 10.1016/S1006-706X(13)60216-2

The mechanical properties of heat affected zone （HAZ） of two commercial high-Nb X80 grade pipeline steels with different alloy elements were investigated using thermal simulation performed on a Gleeble-3500 thermal simulator. The results showed that the high-Nb steels have excellent weldability. Ernbrittlement regions appear in coarse grain heat affected zone （CGHAZ） and intercritically heat affected zone （ICHAZ） ~ Softening region appears in fine-grain heat affected zone （FGHAZ）, and the strength here was even lower than 555 MPa as required in the standard. Meanwhile, with the increase of heat input, the strength and the toughness of HAZ of steel with high Nb, C and lower alloy decrease notably. Therefore, take into account the welding procedure during manufacture of weld pipe, suitable amount of alloy elements, such as Cr, Ni, Cu, Mo and so on, is necessary for high Nb X80 heavy- thick steel plate.