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１５ＭｎＶＮｑ－Ｃ钢为九江长江大桥主要用钢．其过热区低温韧性较优化前１５ＭｎＶＮｑ－Ａ钢有大幅度改善。为分析１５ＭｎＶＮｑ－Ｃ钢焊接过热区低温韧性改善的原因，本文采用热模拟技术对比研究了过热区组织及其对韧性的影响，过热区Ｖ（Ｃ、Ｎ），Ｔｉ（Ｃ、Ｎ）的析出行为及其析出相对组织和韧性的影响。结果指出，含微量Ｔｉ（０．０１２％）的１５ＭｎＶＮｑ－Ｃ钢过热区低温韧性的改善与难溶的ＴｉＮ析出相粒子有关。由于微量Ｔｉ的存在，降低了过热区固溶Ｎ含量，促进了韧性较高的针状铁素体的形成，从而改善了过热区的低温韧性。
15MnVNq-C steel for the Jiujiang Yangtze River Bridge main steel. The overheating zone of low temperature toughness before optimization 15MnVNq-A steel has greatly improved. In order to analyze the reason of low temperature toughness improvement in 15MnVNq-C steel overheated zone, the thermal simulation was used to study the microstructure and the influence on the toughness of the overheated zone. The overheating zone V (C, N) and Ti (C, N) Behavioral and its impact on the relative organization and resilience. The results indicate that the improvement of low temperature toughness of 15MnVNq-C steel with a trace amount of Ti (0.012%) is related to the precipitation of precipitated particles of TiN. Due to the presence of trace amount of Ti, the content of solute N in the overheated zone is reduced and the formation of acicular ferrite with high toughness is promoted, thereby improving the low temperature toughness of the overheated zone.