Research On Property Of Super-high Manganese Steel And High Chromium Cast Iron And The Appliance Research Of LFC Process On Large Heat-resistant Crucible And Water Pump Impeller

The effect of ageing treatment on microstructure and strain hardening ability during the process of uniaxial small compressive deformation of Super—high manganese steel was investigated. The results showed that the strain hardening ability of super—high manganese steel could be enhanced by appropriate ageing treatment meanwhile the strain hardening ability was not relevant to initiative hardness. For the Super—high manganese steel treated by various ageing techniques , the relation between true stress and true strain accorded with Hollomon equation in sections, behaving as double n, getting excellent hardening under small compressive deformation. the microstructure of the dense dislocations, some stacking faults, the great amount of deformation twins, some intersecting twins and ultrafine carbides in a nano-scale has been observed under the condition of the uniaxial small scale compressive deformation. By thin film TEM observed and X-ray structure analysis no deformation-inducing martensite has been observed, and it is shown that the work hardening mechanism of Super-high manganese steel can be attributed to composite strengthening of dislocation , twin, stacking and precipitation of ultrafine carbides.The effects of quenching process (including austenitizing temperature, austenization holding time and quenching rate) and temper temperature on mechanical properties of KmTBCr26 high chromium cast iron have been investigated by measuring hardness and impact toughness. The results show that the quenching process has prominent well-regulated influence on the hardness of the samples, and the optimal austenitizing temperature which produce the highest hardness is 980~1020°C and the optimal austenization holding time is related to the original microstructure of samples, while the data of impact toughness of samples in various quenching process treatments is ruleless. The results also show the transformation of martensite and austenite after quenching to ferrite-carbides with temper temperature increasing, and that the temper temperature hasprominent well-regulated effect on hardness and impact toughness, the results also indicated that the synthetic mechanical properties of the material became excellent when temper temperature was 460℃.In this paper, the technique and essentials of process control of ZG20SiMn water pump impeller and heat-resistant cast steel crucible in lost foam casting were discussed, it was pointed that a lot of superiority of LFC were exerted sufficiently for water pump impeller of the thin wall and the complicated shape. The relevant casting defects were relieved or eliminated through designing the casting system in reason, selecting conectly refractory coating and molding sand and increasing the filling density of molding sand, at the same time the quality of the complex and near net shape casting in LFC was improved. For the large thin wall casting, higher density foam was adopted to prevent the deformation as well as collapse. It is helpful to prevent collapse by decreasing appropriately permeability of coating. In addition, it is very necessary to adopt the assistant abstraction barrel for semi-closed cavity.