The Investigation Of Casting Martensite Precipitation Hardening Stainless Steels Impeller Materials And Technics

The investigations on turbo compressor casting impeller's material and casting, hot isostatic pressing and vacuum heat treatment technics.was made to replace welding impellers and milling impellers. It's very important to save energy sources, decrease costs and shorten producing periods.The test material is ZG0Cr13Ni5Mo2Cu2Nb, which is named FV520(B) generally. The casting methods include investment static casting and centrifugal casting. The hot isostatic pressing (HIP) and vacuum heat treatment are made after casting. The test analyses the effects on smelt and casting to ZGOCr13Ni5Mo2Cu2Nb steel's mechanical property and impeller's shaped quality. The centrifugal casting in vacuum furnace with electroslag remelting steels is best method.HIP improves the strength, plasticity, toughness and fatigue resistance. Homogenizing treatment can makes steel's chemical composition more even, and homogenizes microstructure so that it improve integrate mechanical property.The solution treatment temperature of ZGOCr13Ni5Mo2Cu2Nb steel is 1100℃ mostly. Considering heat treatment deformation and cost, the solution treatment temperature may be 1050℃ too. Following middle treatment increasing, the material's strength and hardness increase and it's plasticity and toughness decrease appreciably. The material gain higher plasticity and toughness with middle treratment at 750℃ commonly, and gain higher strength at 850℃.The intensity peak value aging temperature of ZGOCr13Ni5Mo2Cu2Nb steel is between 450 and 500℃, and it's toughness peak value aging temperature is between 610 and 640 ℃.