Impact toughness and electrochemical corrosion resistance of simulated coarse-grained HAZ of weathering steel Q420qNH

ZHANG Xiazhou; CHEN Yanqing; WANG Fenghui; ZHANG Xi; ZHAO Yingjian

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Impact toughness and electrochemical corrosion resistance of simulated coarse-grained HAZ of weathering steel Q420qNH
Vol. 48, Issue 10, Pages: 48-53(2018)
Published：2018
DOI：
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DOI：

ZHANG Xiazhou, CHEN Yanqing, WANG Fenghui, et al. Impact toughness and electrochemical corrosion resistance of simulated coarse-grained HAZ of weathering steel Q420qNH[J]. Eletric Welding Machine2018, 48(10): 48-53. DOI：

摘要

使用热模拟试验机模拟耐候桥梁钢Q420qNH在不同焊接热输入下热影响粗晶区的热循环过程

研究粗晶区低温冲击韧性和耐电化学腐蚀性能。结果表明

随着热输入的增加

焊接热影响粗晶区组织由板条状贝氏体逐渐向粒状贝氏体过渡

8/5

为30 s时

组织完全为粒状贝氏体

晶粒尺寸逐渐粗化

大角度晶界密度降低

止裂性能降低

吸收冲击功降低。此外

随着热输入的增加

腐蚀电流密度逐渐上升

交流阻抗值逐渐下降

焊接热模拟粗晶区的耐蚀性下降。最终确定耐候桥梁钢Q420qNH热输入不宜超过36 kJ/cm。

Abstract

Impact toughness and electrochemical corrosion resistance of simulated coarse-grained HAZ of weathering steel Q420 qNH are studied in the paper. The coarse-grained HAZ is simulated by Gleeble2000 D thermal simulation tester upon different heat input energy. The results show that the impact energy decreases with the increase of heat input energy

because the microstructure changes gradually into granular bainite（GB） from lathlike bainite（LB）

and the high-angle grain boundary density of coarse-grained HAZ reduces gradually. In addition

the electrochemical corrosion resistance of coarse-grained HAZ is influenced by the heat input energy.As the heat input energy increases

the corrosion current density gradually increases and the AC impedance value gradually decreases.It is determined that the heat input energy should not exceed 36 kJ/cm for the weathering steel Q420 qNH.