Research Into The Phase Transformation Law And The Properties Regulation Of High Al Steel

The steel Fe-Mn-Al-C with high content of Alumnium is a new kind of lightweight austenitic alloy steel.At present,domestic and foreign scholars mainly study its strength,lightness and equilibrium structure,however,its evolution law and wear resistance is not carried out in-depth study.In this paper,the thermodynamic calculation software is used to design the steel material composition.The methods OM,SEM,TEM are used to study the effects of different alloy element contents and different heat treatments on the structure and performance of the high Al steel.The impact abrasion test for wear resistance of the high Al steel were carried out.The results show that the change of Al content itself has little effect on the steel structure and it is found that the increase of C,Mn,Al and Si content in the test steel can help increase in the precipitation of carbides,increase in the hardness and decrease in the impact toughness and plasticity.With the change of heat treatment processes,it is found that Fe-20Mn-6Al-1.5C-5Cr steel carbide first dissolved in the austenite matrix and then gradually precipitated forming the small dispersed k-carbides in the process of aging,under the condition of forging at 1200 ? for 2 hours,the solution treatment at 1150 ? for 2 hours and at aging treatment at 550 ? for 2 hours,but over-aging will produce lamellar grain boundary k-carbides.The impact wear test was carried out,and it is found that the wear surface of the test steel shows three kinds of appearance : plastic deformation,abrasive grain embedding and cutting furrow.The surface of the test steel without Al exhibits less cutting furrow morphology,and the high-Al test steel exhibits a large area of cutting furrow morphology.In the case of the same alloying elements,the main wear form of the cast steel is the cutting furrow wear.In the continuous impact wear test,there is a certain amount of holes,faults and other internal defects in the steel sub-surface.After the impact wear test,there is a surface hardening phenomenon of about 60?m thick,the hardness of Mn13 test steel is more average,and the hardness of Al-free high-Mn steel is obviously decreased.There is no Al steel and high-Mn high-Al Steel hardness fluctuates greatly,while the forging Fe-20Mn-6Al-1.5C-5Cr steel hardness is more uniform,there is a significant hardening layer and the overall hardness value is higher.