Effect Of Heat Treatment On Corrosion-Wear Resistance In Molten Aluminum Of Fe-Cr-B Cast Steel

In the process of casting of aluminum and hot-dip aluminizing of steels,the load-bearing components often fail due to the synergism of corrosion and wear in molten aluminum,which directly increases the cost of production.As a new wear-resistant material,high boron iron based alloy has excellent wear resistance,and the boride in the alloy has excellent corrosion resistance to molten aluminum,this indicates that it is a promising material with corrosion-wear resistance in molten aluminum.Heat treatment has an important effect on the microstructure and mechanical properties and wear resistance of high boron cast iron-based alloys,however,the effect of heat treatment on its corrosion and corrosion-wear resistance in molten aluminum has not been reported.In this paper,Fe-Cr-B cast steels were prepared by sand casting,the effects of different heat treatment on the microstructure and mechanical properties of Fe-Cr-B cast steels were studied.In addition,the influence of heat treatment on corrosion resistance and corrosion-wear resistance in molten aluminum of Fe-Cr-B cast steels were investigated emphatically.The main conclusions are as follows:(1)Fe-Cr-B cast steel can achieve better comprehensive mechanical properties after destabilising at 1000?-1050? and tempering at 200?-300?.In the range of 850?-1100?,the continuity of boride in Fe-Cr-B cast steel M1(16.2wt.%Cr-1.7wt.%B-1.7wt.%Mo)and cast steel M2(13.0wt.%Cr-1.8wt.%B-1.9wt.%Mo)decreases with the increase of destabilization temperature,while the amount of secondary borocarbide precipitates increased first and then decreased,and reaches the maximum value after destabilized at 900? for 1h;The hardness of M1 and M2 increases first and then decreases with the increase of destabilization temperature,while the variation trend of fracture toughness is opposite.Both M1 and M2 showed a strong secondary hardening effect.(2)The corrosion resistance in molten aluminum of as-cast M1 and M2 is about 4.5 times and 3.8 times that of H13 steel,respectively,and the M2B-type(M=Fe,Cr,Mo)borides in the cast steels play a role in retarding the corrosion of molten aluminum;The corrosion rate of M1 decreases first and then increases with the increase of the destabilization temperature,and the minimum value is obtained at 900?;When the corrosion time is 8h,the corrosion rate of cast steel M1 destabilized at 900? for 1h is about 25.1% lower than that of as-cast M1;The dispersed secondary borocarbides precipitated after destabilizing treatment have excellent corrosion resistance to molten aluminum,which effectively hindered the progress of the reaction diffusion,thereby improving the corrosion resistance of Fe-Cr-B cast steel to molten aluminum.(3)Under the condition of corrosion-wear in molten aluminum at 750?,the corrosionwear weight loss of cast steel M1 destabilized in the range of 900?-1050? is less than that of the as-cast M1,and the minimum value is obtained after destabilized at 1000? for 1h,which is about 11% lower than that of as-cast condition;Corrosion accelerates the wear,while wear also accelerates the corrosion,the synergism of corrosion and wear is the main reason for the corrosion-wear failures of Fe-Cr-B cast steel in molten aluminum.