Research Of The Effect About Chromium And Manganese Content On Structure And Properties Of High Carbon Gray Cast Iron

In this paper, we make the research through the theoretical analysis and experimental research, high carbon cast iron on the chemical composition of the production process mechanical properties and microstructure, and determined by the production high strength and high carbon iron best chemical composition and production process. In order to improve the mechanical properties of high carbon gray cast iron, in this experiments were to join in chromium and manganese alloy elements, of the high carbon gray cast iron sample chemical testing mechanical test microstructure and fracture morphology analysis as to find out the high carbon improve mechanical properties of grey cast iron the way and method of this project is the most important.Through the experiment, the study found that chemical composition, Carbon is 3.7% Manganese is 0.8%Chromium is 0.2% of the high carbon gray cast iron overall mechanics performance of the best, the most ideal metallographic structure.In production process, the chromium and manganese alloy elements before the furnace of alloyed way to join in, can greatly reduce the burning of the smelting, reduce the error, can also increase the reliability of the experimental data.In mechanical performance, as the Manganese elements join in, high carbon gray cast iron tensile strength after the first increases and fallen slightly, the hardness is after the first decline and then rise. With the compare of the four different carbon content of high carbon gray cast iron is that when the carbon content 3.7% Mn elements in the content of 0.8%. High carbon gray cast iron sample overall mechanics performance of the best, tensile strength for 182 MPa, hardness value for 185 HBS.As the Cr element to join with high carbon gray cast iron tensile strength and wavy change, after first increases, it fell and then dropped sharply increased slightly last; Hardness changes have been showing up for the trend of the element content of 0.2% when Cr, high carbon gray cast iron sample of mechanical performance overall best, tensile strength for 195 MPa, hardness value for 207 HBS.In metallographic organization, chromium manganese alloy element has refined graphite the function of the organization, when Mn element content was 0.6%, graphitization more serious, graphite and thin grow again; Content of 0.8%, graphite and thin have short, graphite is also relatively little, when Mn element content is 0.9%-1.0%, metallographic organization mainly by the type A graphite and d-type graphite composition, and is associated with free cementite NSW; Cr element to join with, graphite organization changing, when Cr elements to more than 0.4%, metallographic picture began to appear d-type graphite, and with the increase of Cr element d-type graphite range is more and more big; When Cr element content than the 0.5% in the microstructure of start exhalation free cementite, with Cr element add more and more in the content of 0.8% from Cr elements.The fracture of high carbon gray cast iron morphology analysis, the conclusion of alloying elements not to join the fracture morphology, a section of crystalline, there are many glance strongly small facets, matrix organization are many sharp edges, belong to wear crystal fault; When join 0.8% of Mn alloy elements, fracture relatively more even small organization, matrix organization pointed in relatively few; When Mn alloy elements to content is 0.8%Cr alloy elements to content is 0.2%, most even tiny fracture organization, and the organization was pointed that basically no sharp chromium manganese alloy element has optimized base structure, control crystallization in the size of the grain, refining the role of graphite, thus greatly reduces the graphite matrix of the separate function, improve the high carbon cast iron mechanics performance.The results show that the chromium manganese alloy elements is not only maintains high carbon gray cast iron excellent heat damping performance but also to meet the requirements from mechanical properties to reduce the production cost point of view, this kind of cast iron have considerable economic benefit and social benefit and has high practical value and popularized significance.