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本文对F12马氏体钢与ZG15crIMoV珠光体耐热钢异质接头的焊接,在江苏谏壁电厂三十万瓩机组施工中,分別选用热817、热407、热337三种焊条,在常温状态下并经运行温度555℃时效后对碳扩散的问题进行了试验,对裂缝的产生作了综合分析。这类异质接头,当焊前和焊接过程中的预热温度、焊后热处理不当及氢的原因将导致裂缝的产生。选用热817或热407焊条的焊接接头均产生碳扩散,前者硬度高冲击韧性低,后者对裂缝的敏感性较大。用热337焊条的焊接接头,对防止碳扩散有显著效果,机械性能也较满意,为保证其高温强度与F12钢管相等,焊缝中心厚度必须为F12钢管厚度的1.2倍以上。为此对电力部颁布的电力建设施工及验收技术规范(火力发电厂承压管道焊接篇)中:“焊接异种钢焊条(焊丝)及焊后热处理温度推荐表”内关于12—cr—IMo—V与1 1/2cr—1/2Mo,Icr—1/2Mo—V等低合金耐热钢焊接时,为防止碳扩散,不应推荐热407焊条,应推荐含铌元素的如热337焊条为佳。
In this paper, welding F12 martensitic steel and ZG15crIMoV pearlite heat-resistant steel heterogeneous joints, Jiangsu Jianbi Power Plant 300,000 瓩 unit construction, were selected hot 817, hot 407, hot 337 three kinds of welding rod, at room temperature state Under the operating temperature of 555 ℃ after aging on the issue of carbon diffusion test carried out a comprehensive analysis of the production of cracks. Such heterogeneous joints, when pre-welding and welding process, preheating temperature, improper post-weld heat treatment and hydrogen will lead to the formation of cracks. The use of hot 817 or hot 407 welding rod joints produce carbon diffusion, the former high hardness and low impact toughness, which is more susceptible to cracks. With hot 337 welding rod joints, to prevent carbon diffusion has a significant effect, mechanical performance is also more satisfactory, in order to ensure that its high temperature strength and F12 equal to the center of the weld pipe thickness of F12 pipe must be 1.2 times more. To this end, the Ministry of Electric Power issued the construction and acceptance of electric power construction specifications (thermal power plant pressure pipe welding articles): “Welding dissimilar steel electrode (wire) and heat treatment temperature after welding table recommended” on the 12-cr-IMo- V and 1 1 / 2cr-1 / 2Mo, Icr-1 / 2Mo-V and other low-alloy heat-resistant steel welding, in order to prevent the proliferation of carbon, heat 407 electrodes should not be recommended, good.