Effects of V–N Microalloying on Microstructure and Property in the Welding Heat Affected Zone of Constructional Steel

Metals

Shengjie Yao¹  Guodong Wang²  Kaiyu Cui²  Hongyun Zhao²  Xinchen Nan²  Haifeng Yang²  Zhengrong Li³ 

[1] Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology (Weihai), Weihai 264209, China;State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China;State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization, Pangang Group, Panzhihua 617000, China;

关键词: vanadium;    nitrogen;    constructional steel;    HAZ;    microstructure;    hardness;   

DOI  :  10.3390/met12030480

来源: DOAJ

【 摘 要 】

Shielded metal arc welding and welding thermal simulation experiment were carried out for constructional steel containing 0% V and 0.10% V, and the microstructure, precipitation feature, microhardness HV0.2, and −20 °C impact value in the welding heat affected zone (HAZ) were investigated. The results showed that in the coarse-grained heat affected zone (CGHAZ), V and N were completely dissolved in the matrix of steel containing 0.10% V to promote the growth of prior austenite grains, meanwhile the fraction of high angle grain boundaries (HAGBs) decreased, thereby leading to the mean −20 °C impact value decreases from 87 J to 18 J. In the grain refined heat affected zone (GRHAZ), V(C, N) precipitates experience re-dissolution and re-precipitation at grain boundaries, V–N microalloying changes the microstructure from lath bainite + granular bainite + small amount of polygonal ferrite to polygonal ferrite + pearlite + martensite, thereby leading to the mean microhardness decreases from 335 HV0.2 to 207 HV0.2, and the mean −20 °C impact value decreased from 117 J to 103 J. In the intercritical heat affected zone (ICHAZ), V(C, N) precipitates experience re-dissolution, re-precipitation, and growth, causing the formation of micro-sized V(C, N) precipitates, thereby leading to the mean −20 °C impact value decreases from 93 J to 62 J.

【 授权许可】

Unknown