Casting Technology And Material Research On Cylinder Block Of Automobile Engine

2.4L gasoline engine is a new type of engine produced JAC company .This text has proceeded to a study principally in two aspects: casting process parameter optimization and influence of mixture ratio of alloy elements on cylinder block casting properties. The casting process parameter optimization concerns mainly determination of the essential process parameters for mold making , core making, multiple-core and melting through test;the mixture ratio of alloy elements mainly study Cr, Sn, Cu content influence on the cylinder block casting's microstructure and mechanical properties.Through technology research shows, according to the size of casting and the shape of sand box, can used two molds in one box; using cold box making cores, can ensure cores size precision, have a good breaking the ranks, and casting inner surface finish high; Using the advanced"Key-core"multiple-core technology, all cores will assembling together in the core ministry, overall coatings, drying, then used the core fixture setting core at mold department. Using cupola and electrical furnace double smelting .use two inoculations method. Iron liquid's quality has greatly improved. Designing close-open gating system,using ceramic screen to block slag. Make the gating system both have the function of block slag and iron liquid filling smoothly. Using above processes to meet production requirement.The mixture ratio of alloy elements study when the content of Cr is range from 0.308%to0.343%, we found the pearlite's quantity does not increased and distance between commutator segment also hasn't upgrade, but the hardness and strength have a up-trend overall the casting parts, and not only surface hardness but also cross-sectional hardness all rised evenly and during the scope of 10to 25 HB. The rising amplitude of strength is very larger, most parts increased 20 to 30 MPa. When added the cylinder Sn content can improving the casting's Brinell hardness and raising the amount of pearlite. In addition can significantly and organizations of the pearlite content, But the lamella pearlite grading cementite and reduce the amount had no effect. When the content of tin is increased from 0.041% to 0.102%, we found tin's content has little influence on pearlite's refinement. Every part's surface hardness has obvious increase. When the Cu content of cylinder is increased from 0.354% to 0.602%, we can found the A-type graphite has increase and the graphite changed thicker and shorter, the amount of pearlite in cylinder reach a higher level. The hardness and strength have an up-trend overall the casting parts. Chromium copper composite gray iron chrome, copper better play their respective roles.Considering the manufacturing property and the demand of body-strength totally, this type of cylinder-block should have the composition as follows: C=3.25~3.4%,Si=1.90~2.10%,Mn=0.60~0.90%,S=0.06~0.10%,P≤0.06%,Cr=0.20~0.35%,Sn=0.06~0.09%.