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阀门密封面由于受到磨损,经常采用堆焊的办法进行修复。要求堆焊焊条在室温下硬度不能太高,以便切削加工;而在运行的高温下,应保持较高的硬度;对焊条还要求具有较好的焊接性能。堆557硼是属于16Cr20Ni8sih6B用于600℃以下的高压阀门密封面的堆焊焊条,基本上可以满足上述要求。高桥热电厂有一批材料为2Cr13的阀门阀芯,曾选用堆557硼焊条进行堆焊,其堆焊工艺如下: 堆焊前,先将阀芯预热到500～600℃,然后进行堆焊,焊后立即进行680～720℃回火处理。但在进行切削加工时,金属成块地爆裂。虽经多次回火,仍无法进行切削加工。经金相分析研究,此种焊条,其堆焊层金属组织结构是奥氏体加少量碳化物和少量硅共晶,还有少量的铁素体。这种焊条的堆敷金属所以有较高的硬度、
Valve sealing surface due to wear and tear, often using surfacing approach to repair. Requirements surfacing electrode hardness at room temperature can not be too high, in order to cutting; and at high temperatures, should maintain a high hardness; also requires the electrode has better welding performance. Heap 557 boron is 16Cr20Ni8sih6B 600 ℃ for the following high-pressure valve sealing surface welding electrodes, basically meet the above requirements. Takahashi Thermal Power Plant has a group of materials for the valve spool 2Cr13, had selected heap 557 boron electrode surfacing, the surfacing process is as follows: Before surfacing, the valve core preheated to 500 ~ 600 ℃, and then surfacing, Welding immediately after the 680 ~ 720 ℃ tempering. However, during the cutting process, the metal burst into blocks. Despite repeated tempering, still can not be cut. Metallographic analysis of the study, the electrode, the surfacing metal structure is austenitic plus a small amount of carbide and a small amount of silicon eutectic, as well as a small amount of ferrite. This electrode deposited metal so have a higher hardness,