Liu Yang, Ma Heng, Wang Zhaoyu, Chen Xuehui, Huo Xiaoxin, Wu Hongyan, Du Linxiu
The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China.
Laiwu Iron and Steel Group, Yinshan Steel Co., Ltd., Jinan 271104, China.
Materials (Basel). 2025 Mar 4;18(5):1148. doi: 10.3390/ma18051148.
In order to find the optimal heat input for simulating the welding of the coarse-grained heat-affected zone (CGHAZ) of a novel Q690 MPa V-N microalloyed medium and heavy plate, the study investigated the precipitation of V (C, N), microstructural changes, and impact toughness under five different heat inputs (E). The results show that in the CGHAZ, as the heat input increases, the dominant microstructure changes from intragranular acicular ferrite (IGAF) and lath bainitic ferrite (LBF) to polygonal ferrite (PF) and a small amount of IGAF. At the same time, the area fraction of the brittle phase martensite/austenite (M/A) constituents increased from 4.96% to 7.95% as heat input increased, and the microhardness difference between the M/A constituents and the matrix significantly increased. In addition, with the E increases, the fraction of high-angle grain boundaries (HAGBs), which can hinder crack propagation, increases from 59.2% to 62.2% and then decreases from 62.2% to 49.3%. Moreover, the impact toughness of the simulated CGHAZ of the Q690 MPa V-N microalloyed medium and heavy plate first increases from 62 J to 100 J and then decrease to 20 J.
为了找到模拟新型Q690 MPa V-N微合金化中厚板粗晶热影响区（CGHAZ）焊接的最佳热输入，该研究调查了在五种不同热输入（E）下V（C，N）的析出、微观结构变化和冲击韧性。结果表明，在CGHAZ中，随着热输入的增加，主要微观结构从晶内针状铁素体（IGAF）和板条贝氏体铁素体（LBF）转变为多边形铁素体（PF）和少量IGAF。同时，随着热输入增加，脆性相马氏体/奥氏体（M/A）组元的面积分数从4.96%增加到7.95%，且M/A组元和基体之间的显微硬度差异显著增大。此外，随着E增加，能够阻碍裂纹扩展的大角度晶界（HAGBs）的比例从59.2%增加到62.2%，然后从62.2%降低到49.3%。而且，Q690 MPa V-N微合金化中厚板模拟CGHAZ的冲击韧性先从62 J增加到100 J，然后降低到20 J。
