激光合金化Mn-Al2O3和Mn-Al2O3-NiWC涂层的磨蚀性能研究

为了提高不锈钢桨叶的表面耐磨蚀性能,采用激光合金化技术在1Cr18Ni9Ti不锈钢表面制备了Mn-Al2O3和Mn-Al2O3-NiWC合金化层,原位获得均由枝晶、共晶和未熔氧化铝颗粒组成的高锰钢基复合耐磨蚀涂层,并通过正交试验研究了两种合金化层的显微组织和耐磨蚀性能。结果表明,所有的正交参量下激光合金化Mn-Al2O3均可提高不锈钢的耐磨性,但耐蚀性有的提高,有的降低;参量因素对合金化层耐磨性的影响顺序为Al2O3添加量、扫描速率、激光功率,对耐蚀性的影响次序则恰恰相反;Al2O3添加量决定了Mn-Al2O3复合涂层中硬质相的含量,从而决定了涂层硬度和耐磨性;两种合金化层表面均发生晶界腐蚀、晶粒内和晶界处的点蚀,其耐蚀性与其多种组织、物相及各自的化学成分和耐蚀性及组织均匀性相关。

Wear corrosion properties of laser alloyed Mn-Al2O3 and Mn-Al2O3-NiWC layers

The alloyed layers of Mn-Al2O3 and Mn-Al2O3-NiWC were fabricated on 1Cr18Ni9Ti stainless steel by laser surface alloying to improve wear-corrosion resistance of stainless steel blades. High Mn-matrix composite coatings were in-situ fabricated which were composed of dendrites, eutectics and undissolved Al2O3 particles. Microstructure, wear and corrosion behavior of both the alloyed layers were investigated by orthogonal experiments. The results show that wear resistance is improved under all 9 sets of orthogonal parameters, while corrosion resistance is improved or decreased, varying with parameters. Wear resistance of the alloyed layers is influenced most by the addition amount of Al2O3, followed by scanning speed and laser power, while corrosion resistance is influenced inversely. Addition amount of Al2O3 affects the hard phase amount in the alloyed layers, determining hardness and wear resistance of the alloyed layers. Intergranular corrosion in combination with pitting in the grains and grain boundaries are observed in both kinds of alloyed layers. Corrosion resistance is determined by the various microstructure, phases, the unique chemical composition and corrosion characteristic of the phases and the homogeneity of the microstructure.