The factors affecting dimensional accuracy and precision of retention of lathe body castings are material rigidity,residual stress and deformation.In the present research,Y-type blocks and stress frames were poured,and tensile test,metallographic test,scanning electron microscope analysis,and massive residual stress measurement were carried out.The effects of alloying elements(Cu,Mn,Sn,Cr,Ni),silicon content,carbon equivalent,shakeout temperature and aging treatment on elastic modulus and residual stress of gray iron and ductile iron were studied.T-type lathe bedway samples were poured for production verification.Results show that alloying elements,silicon content,and pearlite have significant effects on the elastic modulus of ductile iron.The change range of elastic modulus of ductile iron samples is between 147 GPa and 177 GPa.Ductile iron with 0.5-0.7%Cu,0.4-0.6%Mn,and 0.04-0.06%Sn has high tensile strength(≥ 600 MPa)and elastic modulus(≥ 160 GPa).The higher the carbon equivalent,the lower the residual stress of gray iron and ductile iron.Lower shakeout temperature can help to reduce the residual stress.The residual stress of gray iron and ductile iron is below 20 MPa and 50 MPa,respectively,after “multi-step temperature rising/falling” heat aging treatment.It is an effective approach to obtaining high-rigidity lowstress QT600-3 ductile iron by 0.5-0.7%Cu,0.4-0.6%Mn,and 0.04-0.06%Sn compound alloying and a “multi-step temperature rising/falling” heat aging under higher carbon equivalent(4.4-4.6%)condition.A high-rigidity low-stress QT600-3 ductile iron beam casting was successfully made.