激光单道与多道熔覆Ni+Cr_3C_2复合涂层的组织及硬度

Structure and Hardness of laser-clad Ni+Cr_3C_2 Composite Coatings with Single and Overlapping Clad Tracks

对激光单道与多道搭接熔覆Ni+Cr3C2 复合涂层的组织、硬度及其影响因素进行了研究。在6 0mm× 1 0mm× 1 0mm(多道熔覆 )和 6 0mm× 2 0mm× 1 0mm(单道熔覆 )两种 45钢基材试样上 ,采用同一激光处理工艺参数 (P =1 7kW ,Vs=5mm·s- 1 ,D =3mm)熔覆同一涂层材料 (Ni + 50 %Cr3C2 ) ,涂层的成分、组织随搭接工艺不同 ( 0和 0 5搭接率 )而发生变化 ,使单道与多道熔覆层的显微硬度分别为1 1 0 0～ 1 2 0 0HV和 380～ 480HV。多道搭接熔覆产生的重稀释导致涂层中的硬质相数量明显少于单道熔覆层 ,是造成涂层硬度下降的主要影响因素。对激光熔池的凝固速率以及“二次加热”产生的熔道退火效应对涂层硬度的影响进行了分析。

The structure and hardness as well as their influential factors of laser\|clad Ni+Cr 3C 2 composite coatings with a single clad track (SCT) and overlapping clad tracks (OCTs) have been investigated. The composition and structure of the coatings change with different techniques of 0 and 0.5 overlapping under same laser treating parameters ( P =1 7kW, V s=5mm\5s -1 , D =3mm) to clad identical coating materials (Ni+50%Cr 3C 2) on 60mm×10mm×10mm and 60mm×20mm×10mm samples of 45 carbon steels. The microhardness of coatings with SCT and OCTs is 1100～1200HV and 380～480HV, respectively. The overdilution produced by OCTs,resulting in the amount of hard phases in the coating with OCTs to be obviously less than that of SCT,is the main influential factors for lowering hardness of the coatings. The influence of solidification rate in laser melt pools and annealing effect caused by repeated heating on hardness of the coating was also analysed.