| The wear-resistant and heat-resistant steel is widely used in the energy development, power machinery, petrochemical, metallurgy. At present, a lot of research about the Austenite of wear-resistant and heat-resistant steel at home and abroad is done, and formed a Cr-Ni-N system, Cr-Mn-N system, Fe-Cr-Ni-Al double Phase alloy steel,but there is few studies to the martensitic of wear-resistant and heat-resistant steel and mainly Concentrated on 2Cr12NiWMoV and 2Cr12WmoVNbB.In this paper, the basis of chemical composition of this alloy were C0.42%, Si0.85%, Mn1.2%, Cr5.25%, Ni0.71%, Mo0.53%.and the alloy contained different aluminum that was form 0% to 2.5%.The effects of Al on the microstructures, conditional mechnical properties, oxidation resistance at 600℃to 800℃and wear resistance of wear-resistant and heat-resistant steel had been researched systematically by optical microscope (OM), X-ray diffractometer (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and so on.The results indicated that the microstructures of the alloys as cast composed of ferrite, pearlite and carbide. With the increasing of aluminum, the ferrite increased. The microstructures of the alloy containing 2.0 wt.% Al and 2.5 wt.% Al appeared a large number of directional distribution ferrite. After 1000℃quenched and 600℃tempered, the microstructures of the alloy containing 0 wt.% Al and 1.0 wt.% Al were tempering sorbite, but the microstructures were tempering sorbite and Fe-Cr-Al carbide when the content of Al were 1.5%,2.0% and 2.5%,and the microstructures appeared the more Fe-Cr-Al carbide as the content of Al increasing.The mechnical properties test of Al-containing wear-resistant and heat-resistant steel showed that the hardness of cast decreased with the content of Al increasing aluminum content increased, there were not very different both the alloy containing 0 wt.% Al and 1.0 wt.% Al, which were 48.4 HRC and 46.4 HRC. The hardness of alloy with 1.5 wt.% Al reduced 35% than that of the alloy without Al, but the downward trend slowed when the content of aluminum increased further. After 1000℃quenched and 600℃tempered, the hardness increased with the aluminum content increasing, there were a slight decrease when the aluminum content of from 2.0% to 2.5%.Among this, the alloy containing 2.0 wt.% Al had the highest hardness,which was 38.3HRC.To the tensile strength,it first increased and then decreased with the aluminum increasing, and its the maximum was 1230Mpa when the content of aluminum up to 2.0%.The oxidation resistance properties test of Al-containing wear-resistant and heat-resistant steel indicated that the oxidation resistance of steel increase and the average oxidation speed decreased when the content of Al increased. The average oxidation rate of steel greatly reduced when the aluminum content reached to 2%, but the oxidation rate would remain basically unchanged as the further increasing of Al. For the alloy with the same content of Al, the higher oxidation temperature was, the more serious oxidation would be. After 150h oxidation at 800℃,the alloy containing 0 wt.% Al and 1.0 wt.% Al appeared a large number of oxide and the knot in a certain convex. The alloy withl.5% aluminum appeared a certain oxide film, and the alloy containing 2.0 wt.% Al and 2.5 wt.% Al oxidation was relatively light. After 150h oxidation at 650℃,the surface oxide film of the alloy containing 2.0wt.% Al consisted of Al2O3, Cr2O3 and Fe (Cr Al) 2O3, while, besides the above oxides, that of the alloy contained Cr2O3 after 150h oxidation at 800℃.The wear properties test of Al-containing wear-resistant and heat-resistant steel indicated that wear resistance improved with the content of Al increasing. The alloy containing 2.0% Al had the minimal wear and the best wear-resistant, but the alloy without Al had the largest wear and the worst wear-resistant. Through the observation and analysis by SEM wear morphology, non-aluminum alloy plough was the deepest, while the alloy containing 1.5%Al,2.0%Al and2.5% Al alloy plough was relatively shallow.Through the research on microstructures and main properties, the optimized content of Al was 2.0 wt.%. The microstructure of wear-resistant and heat-resistant steel containing 2.0wt.% Al as cast composed of ferrite, pearlite and carbides. The microstructure were tempering sorbite and Fe-Cr-Al carbide after 1000℃quenched and 600℃tempered. The tensile strength was 1230MPa at room temperature. The average oxidation speed was 0.0095g·m-2·h-1 at 650℃, while it was 0.0285g·m-2·h-1 at800℃. The wear rate of frictional wear was 1.441m·mg-1 at room temperature.Because of excellent high temperature oxidation resistance and wear resistance, the alloy containing 2.0% Al can be widely used in the straightening roller and the wear-resistant and heat-resistant equipment of alumina and cement industry, so it has a high engineering value. |
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