碳钢Cr-Ti共渗及Al-Ti共渗层的组织和性能

Structure and properties of Cr-Ti and Al-Ti coatings on carbon steel

为了提高碳钢构件的硬度、耐磨性和耐蚀性,对35钢及20钢实施Cr Ti共渗及Al Ti共渗,用X射线、EPMA、显微硬度及摩擦磨损实验等分析测试方法,研究了渗层的组织和性能.结果表明,35钢Cr Ti共渗层外侧富Cr、内侧富Ti,在3.5%NaCl和10%H2SO4溶液中有良好的耐蚀性;渗层表面硬度HV0.2=1900,耐磨性比17Cr2Ni2Mo渗碳钢对比试样提高3倍.35钢Al Ti共渗层外侧富Ti、内侧富Al,在10%H2SO4溶液中的耐蚀性较差;渗层表面硬度为HV0.2=400,但耐磨性仍比对比试样提高近一倍.

Cr-Ti and Al-Ti binary thermo-chemical treatment has been carried out on 35 and 40 carbon steel to increase hardness, wearing resistance and corrosion resistance. The structure,composition and properties of the coatings are characterized by X-ray diffraction ,EPMA,microhardness test and wearing test. The results indicate that there is a chromium-rich zone at the outside and a titanium-rich zone at the inside of the diffusion-alloying coatings on 35 carbon steel for the chromium-titanizing, so the specimens have better corrosion resistance in the 3.5%NaCl and 10%H 2SO 4 solution. The microhardness for the coatings is about HV 0.2 = 1 900 and the wearing resistance has been increased three times as compared with carburizing-annealing 17Cr2Ni2Mo steel. In the case of aluminum-titanizing, it is found that titanium is concentrated at the outside and aluminum at the inside, but the coatings are weak in corrosion resistance in the 10%H 2SO 4 solution. The coatings have a microhardness of HV 0.2 =400 and its wearing resistance is slightly increased while compared with 17Cr2Ni2Mo steel,