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1981年,我厂金工车间磨床班职工发现一批用于ND_4型内燃机车的柴油机进气阀座(材料为Cr12MoV钢),在热处理后导磁性下降,不能在平面磨床上进行平面磨削。开始,认为这是材料混乱造成的。但经过化学夺析,结果是含碳1.54％、铬11.80％、钼0.57％、钒0.20％,符合Cr12MoV钢的成份,从而排除了对混料的怀疑。因此,考虑到导磁性下降的主要原因在热处理工艺。一、热处理工艺分析进气阀座在RYD 45-9型中温盐浴炉和RYD35-13型高温盐浴炉中加热。热处理工艺是:预热温度为780～800℃,保温4.5～
In 1981, the workers in the grinder workshop of our factory found a group of diesel engine intake valve seats (made of Cr12MoV steel) for ND_4 diesel locomotives. After the heat treatment, their magnetic permeability dropped and they could not be ground flatly on the surface grinder. At first, think this is caused by material confusion. But after chemical analysis, the result is carbon 1.54%, 11.80% chromium, 0.57% molybdenum, 0.20% vanadium, in line with the composition of Cr12MoV steel, which ruled out the doubt on the mixture. Therefore, the main reason for the decrease of permeability is considered in the heat treatment process. First, the heat treatment process analysis Inlet valve seat in the RYD 45-9-type medium temperature salt bath furnace and RYD35-13-type high-temperature salt bath furnace heating. Heat treatment process is: preheating temperature of 780 ~ 800 ℃, insulation 4.5 ~