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60年代发现有些含有钼钒等合金元素的低合金钢用于制造汽包,当焊缝拘束度大又有应力集中,在消除应力回火时焊缝热影响区有再热裂缝倾向。BHW38和18CuNiMoTi钢均属于再热裂缝敏感的钢。结607镍(SG-2)焊条,在350℃以下与结607焊条有同样的强度,而在350℃以上强度较一般结607焊条低得多,焊后消除应力回火,焊缝首先释放应力,故能预防再热裂纹产生。结607镍焊条用于焊接BHW38钢400吨/时汽包下降管时都避免了再热裂缝产生。用于退修焊补18CuNiMoTi钢汽包封头插入式人孔圈焊缝的大裂缝也取得满意的结果。结607镍焊条虽含有1.4%左右的镍,在350℃长期时效没有发现时效脆化现象。
In the 1960s, some low-alloy steels containing alloying elements such as molybdenum and vanadium were found to be used in the manufacture of steam drums. When the weld confinement is large and stress concentrated, there is a tendency of reheat cracking in the heat-affected zone of the weld when the stress-tempering is eliminated. Both BHW38 and 18CuNiMoTi steels are reheat crack-sensitive steels. The junction 607 nickel (SG-2) electrode has the same strength as the 607 electrode under 350 ° C, and the strength is much lower than that of the conventional 607 electrode above 350 ° C. After welding, the stress-tempering is relieved and the weld first releases the stress , It can prevent reheat cracks. The knot 607 nickel electrode avoids reheat cracking when used to weld the 400 t / h drum drop tube of the BHW38 steel. Satisfactory results were also obtained for the large cracks in welds of 18CuNiMoTi steel drum head plug-in manhole welds repaired. Although the 607 nickel electrode contains about 1.4% nickel, aging embrittlement is not found at 350 ℃ for long time.