Study On Casting Process,Microstructure And Properties Of Mn,Zr Alloyed ZL301 Alloy

ZL301 alloy is a medium-strength aluminum alloy with high specific strength and good corrosion resistance.It is widely used in the shipbuilding industry and the petroleum industry.However,the alloy has high magnesium content and extremely poor casting performance.In this article,through metallographic microscope,scanning electron microscope,transmission electron microscopy,X-ray diffraction analysis,energy spectrum analysis,mechanical property testing and analytical means such as aluminum liquid hydrogen meter,studied different refining processes,pouring temperature,casting shape of composite with Mn,Zr ZL301 the influence of the microstructure and mechanical properties,determine the best casting process,The effects of Mn and Zr alloying on the microstructure and mechanical properties of ZL301 were further studied.The results are as follows:（1）Compared with different refining processes,C₂Cl₆ and argon gas refining have the best refining effect,the melt hydrogen content is the least,the alloy T4 tensile strength is the highest,and the alloy structure is compact without shrinkage.When the casting temperature is between 650℃and 690℃,the tensile strength of alloy T4 is relatively high and stable.When the casting temperature is further increased,the tensile strength decreases,and the obvious shrinkage appears at the fracture.The equivalent thickness of the plate casting is large,the alloy has good fluidity,the alloy T4 tensile strength is high,and local shrinkage occurs in the casting.When the casting temperature and casting speed are increased,the T4 tensile strength of the rod casting increases,but the overall tensile strength of the rod casting is very low,and there is serious shrinkage in the casting.（2）The effects of Mn and Zr addition alone and compound addition of Mn and Zr on the microstructure and mechanical properties of ZL301 in cast and T4 states were studied.In the as-cast state,there is Al₃Mg₂segregation phase distributed along grain boundaries in the ingot microstructure.The addition of Mn and Zr alone and the combined addition of Mn and Zr can refine the grain structure of ZL301 alloy and improve the tensile strength of the alloy.The combined addition of Mn and Zr has the most significant effect on grain refinement of ZL301 alloy and the maximum tensile strength of the alloy.The fracture mode of the alloy is brittle fracture.In T4 state,the reticulated Al₃Mg₂ phase is dissolved back into the aluminum matrix,which has obvious solid solution strengthening effect.A large number of Al₆Mn、α-Al（Fe Mn）Si dispersion strengthening phases are precipitated in the matrix of ZL301 with Mn and Zr added,and the tensile strength and yield strength of ZL301 alloy with Mn and Zr added reach the maximum.The fracture mode of the alloy is ductile fracture.Mn can reduce the corrosion resistance of ZL301 alloy,and Zr can improve it.