为获得高硬度、高耐磨性的表面合金层,将镍基自熔合金粉末预先涂覆在Q235钢表面,利用碳弧热源进行熔覆制备熔覆层.通过金相显微镜、硬度计及磨粒磨损试验机对熔覆层表面的组织及性能进行测试,研究焊接电流和涂覆层厚度对熔覆层组织和性能的影响.结果表明:焊接电流相同,增加涂覆层厚度,熔覆层的表面硬度和耐磨性呈现先增加后降低的趋势;涂覆层较薄时,熔覆层硬度、耐磨性随电流增大而下降,涂覆层较厚时,熔覆层硬度、耐磨性随电流增大而呈上升趋势;当涂覆层厚为4 mm,焊接电流为200 A时,组织为镍基固溶体加共晶物,共晶组织为镍基固溶体与多种碳化物、硼化物共晶,硬度最高,为54.3 HRC,耐磨性最好.
In order to obtain high hardness and high wear resistance surface alloy layer,Ni-based self-fluxing alloy powder was pre-coated on the surface of the samnple in advance and then followed by carbon arc cladding.The surface morphologies of cladding coatings were observed with a metallographic microscope,and their hardness and wear resistance were evaluated with a hardness meter and a friction and wear tester.The effect of cladding current and thickness of pre-coated layer on microstructure and mechanical properties of the cladding coating was investigated.Results showed that under the same welding current the hardness and wear resistance of the cladding layer increased firstly and then decreased with the increase of the pre-coated layer thickness.When the cladding current was 200 A and the pre-coated layer thickness was 4 mm,the surface structure of the cladding coatings was γsolid solution and eutectics,of which eutectics was Ni-based solid solution and various carbide and boride,with the highest hardness of 54.3 HRC and the best wear resistance.
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