摘要高速钢具有高硬度、高耐磨性和良好的耐热性，常常被用来制造轧辊。激光熔覆技术是利用高能量密度的激光束将某些具有不同成分、性能的合金材料与基体材料表面迅速结合，以此获得基体材料不具有的一些性能。本文提出了利用激光熔覆技术进行M3:2高速钢熔覆，研究的主要内容如下：87176

以高速钢粉末为熔覆材料，奥氏体不锈钢为基体制备激光熔覆层，采用大功率半导体激光器进行激光熔覆并切割得到所需试样。对激光熔覆层进行显微组织观察和物相分析发现，熔覆材料与基体实现了冶金结合，熔覆层的显微组织比基体更加致密。M3:2高速钢熔覆层的物相组成主要有残余奥氏体、马氏体及MxCy型碳化物。用显微硬度计对熔覆层横截面深度方向的显微硬度进行测量，经研究后发现激光熔覆层表面硬度明显提高，随着激光能量密度降低，熔覆层的平均显微硬度逐渐增大。经热疲劳性能实验可以发现在第一阶段的冷热循环中熔覆层的热疲劳性能表现较好，而在第二阶段的冷热循环中熔覆层迅速产生裂纹并进入快速扩展阶段。并且随着激光能量密度的提高，激光熔覆层的抗裂纹扩展能力也有所增强。

毕业论文关键词：轧辊；高速钢；激光熔覆；显微硬度；热疲劳性能

Abstract High-speed steel with high hardness, high wear resistance and good heat resistance, often used to make rolls。 Laser cladding technique is the use of high energy density laser beam will have some different components, materials and substrate surface binding properties of the alloy rapidly, in order to obtain the base material does not have some performance。 In this paper, the use of laser cladding technique M3: 2 high speed steel cladding, the main contents are as follows:

High-speed steel powder cladding materials, austenitic stainless steel as the base prepared from laser cladding, high-power semiconductor lasers and laser cladding cut to obtain the desired sample。 Laser cladding layer microstructure observation and analysis phase, cladding material and the substrate to achieve metallurgical bonding, the microstructure of the cladding layer is denser than the matrix。 M3: 2 high speed steel cladding of the main phase composition of residual austenite, martensite and carbides MxCy。 Total cross-section of the cladding layer hardness depth direction was measured by a micro hardness, after research found that laser cladding layer surface hardness markedly improved, with the laser energy density is reduced, the average hardness of the cladding layer gradually increases Big。 By thermal fatigue test performance can be found in the first phase of the cycle of hot and cold thermal fatigue properties of the cladding layer performed better, while in the second phase of the cycle of hot and cold cladding layer quickly crack and into the rapid expansion phase。 With the laser energy density and improved resistance to crack propagation capability of laser cladding layer has also been enhanced。

Keywords: roll; laser cladding;hardness; thermal fatigue performance of high speed steel

目 录

第一章 绪论 1

1。1 引言 1

1。2 高速钢轧辊的研究现状 2

1。2。1 轧辊简介 2

1。2。2 热轧辊工作概况 3

1。2。3 高速钢轧辊的发展及研究现状 4

1。2。4 高速钢轧辊的制造工艺 6

1。3 激光熔覆技术 7

1。3。1 激光熔覆原理 7

1。3。2 激光熔覆工艺影响因素