| In the working condition of impact, corrosion and abrasion, traditional crawler board materials like high manganese steel performs poor wear-resisting property for little work hardening. According to the deficiency of the existing material, a kind of low-alloy martensite-bainite dual-phase wear-resistant casting steel to replace high manganese steel has been developed.With the different amount of chromium (Owt%,0.6wt%,1.05wt%respectively) added into steel, the influence of chromium element and microstructure, mechanical properties, corrosion-resisting property and wear-resisting property were analysized. The paper’s contents are as followed:1. The microstructure of different chromium content was observed, the hardness, impact toughness and tensile property of different chromium content steels was tested, finally. The relationship between chromium element and the microstructure, hardness, impact toughness and tensile property of dual-phase steels was studied.2. Dry-wet cyclic accelerated corrosion test and electrochemistry experiment have been carried on high manganese steel and dual-phase steels with different chromium content, the weight gains curve of experimental steels were drawn, the relationship between the chromium element and the corrosion-resisting property was studied.3. Dry grinding and wet grinding experiment was tested on high manganese steel and dual-phase steels with different chromium content, the wear curves of experimental steels were drawn. With the comparation of the M-B dual-phase steels’relative resistance and high manganese steel, the influencing factors of wear-resisting property was analysizd, such as alloying agent, work condition. Using scanning electron microscope to obsever the worn surface and investigate the wear mechanism.The main conclusions were as followed: 1. Bainite and martensite existed in the experimental steels whether it contains chrome or not. With the growth of carbon content and chromium content, the quantity of martensite increased, while the quantity of bainite decreasd and the shape of martensite inclined to lath-shaped. Also the hardness and the impact toughness increased. The impact toughness of chromium-containing steels can reached45J/cm2, which enhanced about8J/cm2compared with non-chromium steels, and the tensile strength was more than1560MPa, the yield strength was more than1260MPa, the elongation was more than6.4%, which satisfied the requriement of the properties of calwer board materials.2. Dry grinding and wet grinding experiment was carried in0.005mol/L NaHSO3solution. The result showed:the weight gains of high manganese steel were the least, the change of rust color is the fastest, darkest. Meanwhile, the rust texture was the most smooth and tightness, the corrosion-resistance is the best. The weight gains of chromium-containing steel were less than the non-chromium steel. With the extension of corrosion time, the difference was more and more obviously. The change of rust color of chromium-containing steel was faster than the non-chromium steel, and the rust texture was moother than the non-chromium steel, so the corrosion-resistance of chromium-containing steel was better than the non-chromium steel. Electrochemical experiment was carried in0.005mol/L NaHSO3solution. The result showed:the corrosion potential of rust specimen was higher and the corrosion current was lower than as-polished specimen, which resulted in the improvement of corrosion-resisting property. But there was little difference between the rust specimens after40wet/dry cycles and80wet/dry cycles.3.No matter in dry grinding or wet grinding, the wear-resistance of M-B dual-phase steels was better than the high manganese steel which widely used as crawler board materials, but there was no obvious difference by raising the amount of the chromium element. In dry grinding condition, the relative wear-resistance of0.6wt%Cr-M-B dual-phase steel advanced56.0%compared with high manganese steel, and the1.05wt%-Cr-M-B dual-phase steel improved58.6%. However, in wet grinding condition, the relative wear-resistance of0.6wt%-Cr-M-B dual-phase steel raised22.5%compared with high manganese steel, and the1.05wt%-Cr-M-B dual-phase steel promoted27.3%. Besides, the addition of chromium in the M-B steel made the corrosion-wear resistance improved.In the wear conditions which had a certain corrosive environment, wear-resistance of steels was influenced by corrosive medium. However, the key influence factors of the steels’corrosion-wear resistance was steels’own wear property.4. The impact fracture pattern showed that the M-B dual-phase steels were mixed fracture which contained cleavage fracture and ductile fracture. From the worn surface, in dry grinding condition, the wear mechanism of M-B duan-phase steel was multiple plastic deformation and secondly micro wear-cutting. However, in wet grinding condition, the wear mechanism of the chromium-containing M-B dual-phase steel was mainly corrosion wear mechanism, and the high manganese steel was mainly micro wear-cutting mechanism. |
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