Dou Guishan, Cao Rui, Cai Changliang, Han Cheng, Guo Xili, Jiang Yong, Chen Jianhong
State Key Laboratory of Advanced Processing and Recycling of Non-Ferrous Metal, Lanzhou University of Technology, Lanzhou 730050, China.
Department of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China.
Materials (Basel). 2021 Feb 15;14(4):926. doi: 10.3390/ma14040926.
The impact toughness of low-Cr heat-resistant steel weld metal is an important problem to broaden the application of low-Cr heat-resistant steel. In this study, the microstructure and impact toughness of 12Cr1MoVR low-alloy heat-resistant steel weld metals with various boron contents (B1 = 0.0028%, B2 = 0.0054%, and B3 = 0.0079%) were investigated. The microstructures of all weld metals were composed of block ferrite, carbides, and inclusions. Results indicated that with increased B content, prior austenite grain sizes decreased, and minor microstructure changes could be found. With the increase in B content from 0.0028% to 0.0054% to 0.0079%, the ductile-brittle transition temperature of the weld metals decreased from 30 to 0 to -14 °C, the toughness of weld metal increased, and the hardness slightly decreased, all of which are directly related to the refinement of prior austenite grain size because of the addition of B content. However, on the top-shelf zone, such as at the testing temperature of 80 °C, ductile fracture dominates the fracture surface; with the increase in B content, the size and density of inclusions increased gradually, which led to the decrease of the impact toughness at 80 °C when the B content was 0.0079%.
低铬耐热钢焊缝金属的冲击韧性是拓宽低铬耐热钢应用范围的一个重要问题。在本研究中，对硼含量不同（B1 = 0.0028%、B2 = 0.0054%和B3 = 0.0079%）的12Cr1MoVR低合金耐热钢焊缝金属的微观结构和冲击韧性进行了研究。所有焊缝金属的微观结构均由块状铁素体、碳化物和夹杂物组成。结果表明，随着硼含量的增加，先共析奥氏体晶粒尺寸减小，且微观结构有轻微变化。随着硼含量从0.0028%增加到0.0054%再增加到0.0079%，焊缝金属的韧脆转变温度从30℃降至0℃再降至 -14℃，焊缝金属的韧性增加，硬度略有下降，所有这些都与因添加硼含量而导致的先共析奥氏体晶粒细化直接相关。然而，在高温区，如在80℃的试验温度下，韧性断裂在断口上占主导；随着硼含量的增加，夹杂物的尺寸和密度逐渐增大，当硼含量为0.0079%时，导致80℃下的冲击韧性下降。
