| In order to effectively control the microstructure and mechanicalproperty of precision casting ZG1Cr11Ni2WMoV which was producedwith investment casting, this paper studied influence of solidification andheat treatment on the microstructure and mechanical properties of alloy.Main achievements are summarized as follows: The different parts ofcasting have various solidification and cooling rate. The thinner part’scooling rate is faster at the temperature where theδ-ferrite and austeniteare forming. The difference of cooling rate and the compositionsegregation result in the different grain size and content of δ-ferrite.When the thickness increasing, The grain size increased89%and the δ-ferrite reached maximum at29mm where the impact toughness is lower.The tensile strength of casting is mainly related with grain size whichdecreases from978MPa to933MPa with thickness increasing from8mmto41mm.Because of the effect of solid solution strengthening and formation of residual austenite, the hardness of ZG1Cr11Ni2WMoV reached themaximum (31HRC) when quenched at1020℃. When tempered between500℃and700℃, lath martensite was gradually decomposed andreversed austenite content increases with temperature increasing. As aresult, hardness and strength of the alloy decreased and the toughnessincreased. When samples were tempered directly without quenching, theimpact toughness would decrease78~91%, and the tensile strength woulddecrease5~7%. |
