Development And Application Of Medium Chromium Wear Resistant Alloy In Slurry Pump

In this paper,the development status of wear resistant materials for slurry pump at home and abroad is briefly introduced.The advantages and disadvantages of the medium chromium cast iron are analyzed and compared.And the future development of medium chromium cast iron in slurry pump is also prospected.On the basis of Cr cast iron in national standard BTMCr8,the contents of C,Cr and Mn were adjusted,and the alloying elements such as Mo and Cu were added.The chemical composition of new medium chromium cast iron used for the parts of slurry pump was designed.And the process tests were carried out,such as casting process,heat treatment process and modification process.On the strength of materials under different conditions of toughness,hardness and wear resistance of a series of properties and microstructure were analyzed,finally we got a good performance,low cost chromium cast iron used in the slurry pump.In this paper,through the analysis of elements on the properties and effects of chromium cast iron,chemical composition of the designing medium chromium cast iron is:C2.9³.2%,Si1.5².5%,Mn2.5².8%,Cr8¹0%,Mo0.6¹.0%,Cu0.1⁰.3%,S?0.1%,P?0.1%.Medium chromium cast iron slurry casting molding process test results show that both the EPC process and resin sand process can meet the technical requirements.The EPC production parts performance is higher than that of resin sand cast parts,the hardness can reach about 50HRC.The results of heat treatment tests for medium chromium cast iron show that the comprehensive performance of the material is best when quenching at 880?and tempering at 250?.The bending strength is increased about by 40%better than the casting.The tensile strength and impact toughness are increased by about 30%.There are martensite,residual austenite,M₃C and M₇C₃,different types of carbide in their microstructures.Relative wear resistance of specimens can be 3.72 times 15 steel,0.75times of BTMCr27.Results of the metamorphic treatment show that adding vanadium modification method can effectively improve the comprehensive performance of chromium cast iron.When the amount of vanadium is 0.1%,the tensile strength and bending strength can be increased by about 30%.The impact toughness is increased by 20%,and the wear resistance is increased by about 10%to 20%.Vanadium can refine grain and improve carbide morphology in medium chromium cast iron.The VC carbide formed by the combination of vanadium and carbon improves the mechanical properties and wear resistance of medium chromium cast iron,but excessive addition of vanadium will lead to the aggregation of too much vanadium carbide and consequent fragmentation of the matrix,resulting in a sharp decrease of the performance for medium chromium cast iron.Therefore,the limited amount of vanadium is about 0.1%.