Effects Of V And Sn On Microstructure And Mechanical Properties Of Gray Cast Iron For Super Large Cylinder Liners

Cylinder liner is an important part of diesel engine.Together with piston and piston ring,it forms the heart of the diesel engine "heart chamber",and its quality determines the performance and life of the engine.Due to the low price of gray cast iron material,high temperature resistance,corrosion resistance,deformation resistance and shock absorption performance,it is widely used in the production of cylinder liner materials.The research in this paper aims to develop a gray cast iron material with excellent comprehensive performance through the alloying of V and Sn alloy elements,so as to solve a series of problems such as complicated processing of super large cylinder liners and dependence on imports,thereby breaking the foreign technology monopoly.Through multiple sets of experiments,the influence of V and Sn alloy content on the microstructure control and performance of gray cast iron castings and the compound effect of different contents of V and Sn elements on gray cast iron castings were analyzed.Through microscopic analysis,the influence of V and Sn alloy elements on graphite structure and matrix structure was studied.The results showed that: both the addition of V,Sn or alloy elements are complex was added to gray iron V,Sn alloy elements,and mechanical properties of tissue inside castings have been significantly improved.After addition of certain alloying elements to gray iron,the graphite can be prompted to refine the casting within the organization,strongly promoting the formation of pearlite structure,pearlite structure stability,so that the pitch refinement of pearlite,thereby improving the mechanical properties of castings.To V elements is concerned,when the element V is added singly,is refined graphite structure,a pearlite content of 98%.In the V content of 0.21 wt.%,preferably mechanical properties,brinell hardness,tensile strength and compressive strength values of 402 HB,1686 MPa and 507 MPa.In terms of Sn element,when Sn alloy element is added alone,the graphite structure is refined to 5-6 level,and almost all of it is pearlite structure in the field of view.The Sn content reaches 0.08 wt.%,preferably mechanical properties,brinell hardness,tensile strength and compressive strength values of 355 HB,1341 MPa and 464 MPa.Similarly when the compound V is added,when the Sn alloy element,with the added elements V and Sn alone,tissue refined graphite,pearlite content increased.When the alloying element content is 0.11 wt.% V and 0.08 wt.% Sn,the mechanical properties are the best.The brinell hardness,compressive strength and tensile strength are 401 HB,1699 MPa and 515 MPa,respectively.In summary,the microstructure and mechanical properties of gray cast iron castings studied in this paper have been significantly improved.In addition,the amount of added elements is small,the cost is low,and the performance requirements for super large cylinder liners can be well met,and it has good application prospects.