Heating Rate of Mn13 high manganese steel frog

Before the Mn13 high manganese steel casting is put into the furnace, the sticking sand , seam and pouring riser on the surface of the casting should be cleaned. Sand sticking has a heat-insulating effect on the heating or cooling of the casting, making the heating and cooling of the casting uneven after entering the water. Severe sand sticking will reduce the cooling rate of the casting after entering the water, causing the re-precipitation of grain boundary carbides. The seam is thin, and decarburization will occur during heat treatment heating. After water quenching, it will transform into martensite. The volume of martensite phase transformation expands, which may cause the casting matrix to crack under tensile stress. The thermal conductivity of Mn13 high manganese steel is low, which is 1/4 to 1/6 of carbon steel below 100℃ and 1/2 to 5/7 of carbon steel at 600℃. The thermal expansion coefficient of high manganese steel is large, which is twice that of carbon steel, and even greater at above 500℃. Although there is no phase change stress in the casting during low-temperature heating, the brittle carbides in the grains and on the grain boundaries will increase after heating to above 300℃, and pearlite transformation may sometimes occur. The structure of Mn13 high manganese steel frog is complex, the wall thickness of the same casting varies greatly, and the casting itself has a considerable casting stress. There is a large temperature difference between different parts during the heating or cooling process of heat treatment, which will produce thermal stress. In this way, the thermal stress and casting stress are superimposed, causing cracks in the frog. Therefore, the furnace temperature and heating speed of Mn13 high manganese steel frog must be controlled.