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Friction stir processing for the modification of laser claded

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Friction stir processing for the modification of laser claded microstructure Ruidi Li1,2,*, Jinglong Li1,2, Jiangtao Xiong1,2, Fusheng Zhang1,2 1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, PR China

2. Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi’an 710072, PR China

* Corresponding author: liruidi@126.com (R. Li)

Key words: laser cladding, friction stir welding, nickel-based alloy, microstructure defects Abstract: According to the microstructure defects of laser claded nickel alloy, such as crack and nets brittle phase, the friction stir processing (FSP) method is utilized in this paper to modify microstructure defects by the coupled effect of thermal and stress of FSP. For this purpose, two key scientific problems of large deformation condition and microstructure evolution theory during FSP, are proposed in this paper. Based on this, the following issues are highlighted in this work. Firstly, obtain the friction condition of larger deformation by continuous dirved friction experiment. Secondly, study on the temperature (T), stress (σ), and strain velocity (ε󰀅) under different processing parameters via self-developed physical simulation apparatus. Thirdly, disclose the effects of T,σ,ε󰀅 on the microstructure evolution and then obtain the microstructure evolution equation by dynamic re-crystallization. The above work could provide theory support for the new technique of laser cladding and FSP for preparing high performance coating.

Introduction Laser cladding, as an effective, high quality, environmental protection coating technology, hold great application potential in many high-tech fields, such as aviation, aerospace, shipbuilding, and steel etc. However, there exist long time puzzled difficulties blocking the development of laser cladding technology, which can be listed as follow. Firstly, the second phase, which usually possesses brittle property, tends to distribute with net structure in solution substrate. In this circumstance, the second phase with net structure, is prone to be cracked when endure loading, owing to the brittle property of second phase could not transmit stress [1]. Moreover, this defect of net distributed second phase is universal in laser cladding of iron, nickel and cobalt based alloys. Secondly, the crack is very easily formed in laser claded layer, especially for the crack sensitive alloy of nickel and cobalt. It is because of the natural instincts of rapid cooling and solidification, which could induce great inner thermal stress. When the stress exceeds the maximum strength of nickel alloy, the crack, tends to be formed spontaneously. It can be seen that the above microstructure defects are hindering the development and application of laser cladding. Although the researcher has done many works according to the above problems, especially the cracks, up to now, the synchronization of preventing the crack and net distributed second phase has not been realized. Therefore, it is urgent to modify the microstructure to prevent the crack and net distributed second phase.

Advanced Materials Research Vols 311-313 (2011) pp 2336-2339Online:2011-08-16© (2011) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.311-313.2336

All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TransTech Publications, www.ttp.net. (ID: 152.14.136.77, NCSU North Carolina State University, Raleigh, USA-19/04/15,09:12:02)Friction stir processing (FSP), as a newly-developed plastic modification surface technology, possesses high temperature, large strain, and rapid strain velocity characteristics [2]. Initially, the generation of FSP drawn lessons from the thought of friction stir welding (FSW) as a solid-phase jointing technology, as shown in Fig. 1. The temperature could elevate rapidly by a stir tool with a high speed revolution, yielding a plastic laser cladding layer. Then the stir tool could transport the material in the front to the back of stir tool combined with the forged effect. The FSP technology could enable the densification, microstructure refining, and elemental diffusion via plastic deformation with high temperature, mixing, crush. Therefore, the FSP technology is an promising technology, which can eliminate the laser cladding defects of cracks and net distributed second phase. Based on the above discussion, this work focuses on the scientific problems of FSP of laser claded layer in order to obtain the theory support of preparation of high performance coating.

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激光熔覆原位生长TiB2

激光熔覆原位生长TiB2

第52卷第7期表面技术2023年7月SURFACE TECHNOLOGY·397·激光熔覆原位生长TiB2/TiC增强铁基涂层组织及性能佘红艳1，屈威1，杨柳1，叶宏1,2（1.重庆理工大学 材料科学与工程学院，重庆 400054；2.重庆市高校模具技术重点实验室，重庆 400054）摘要：目的采用激光熔覆技术在45钢表面制备原位生长的TiB2、TiC陶瓷相，以提高铁基涂层的耐磨性能。

方法利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和能谱仪（EDS）研究铁基复合涂层的相组织、显微组织。

使用显微硬度计、磨损实验机等仪器进行显微硬度和耐磨性的测试。

结果在铁基粉末中添加Ti、B4C后，涂层原位生长出均匀分布的TiB2、TiC陶瓷相，其数量随着（Ti+B4C）添加量的增加而增多。

经过扫描电镜结合EDS判定TiB2多呈矩形形貌，TiC呈球形或花瓣状。

在原位生长过程中，TiB2优先形成，而TiC多依附在TiB2周围，以颗粒状存在。

铁基复合涂层的显微硬度随着（Ti+B4C）添加量的增加逐级增加，质量分数为30%的（Ti+B4C）复合涂层的硬度最高（1 086HV0.2），比铁基涂层（611HV0.2）的硬度提高了约0.78倍。

复合涂层的磨损性能得到明显改善，其中质量分数为30%的（Ti+B4C）复合涂层的磨损率最小，为5.48×10−6 mm3/(N·m)，铁基涂层的磨损率为2.01×10−5 mm3/(N·m)，表明其耐磨性提高了约2.67倍。

随着原位生长的TiB2、TiC陶瓷相数量的增多，铁基涂层的磨损机制由黏着磨损逐渐转为轻微的磨粒磨损。

结论在铁基粉末中添加Ti、B4C，通过激光熔覆技术能够原位生长出TiB2和TiC，显著提高了铁基涂层的硬度和耐磨性能。

关键词：激光熔覆；原位生长；TiB2/TiC；微观组织；显微硬度；摩擦磨损性能中图分类号：TG174.442 文献标识码：A 文章编号：1001-3660(2023)07-0397-09DOI：10.16490/ki.issn.1001-3660.2023.07.036Microstructure and Properties of TiB2/TiC ReinforcedFe-based Coating Grown in Situ by Laser CladdingSHE Hong-yan1, QU Wei1, YANG Liu1, YE Hong1,2(1. School of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054, China;2. Chongqing University Key Laboratory of Mould Technology, Chongqing 400054, China)ABSTRACT: The preparation of ceramic phase reinforced metal matrix composites by laser cladding is currently an important research direction of wear resistant coatings. According to the way of adding the reinforcing phase, they are generally classified into two categories, i.e., the ex-situ method and the in-situ growth method. The significant advantage of in-situ growth is that收稿日期：2022−06−22；修订日期：2022−11−12Received：2022-06-22；Revised：2022-11-12作者简介：佘红艳（1998—），女，硕士生，主要研究方向为激光熔覆表面改性。

美国主办第一届激光冲击强化会议PPT(10)_报告者：西班牙Ljubljana大学

美国主办第一届激光冲击强化会议PPT(10)_报告者：西班牙Ljubljana大学


December 15-17, 2008 NASA-Johnson Space Center Houston, Texas, USA
Experimental results
Microhardness Analysis (HV0,2)
First International Conference on Laser Peening
December 15-17, 2008 NASA-Johnson Space Center Houston, Texas, USA
Experimental results
Pitting Corrosion Analysis
First International Conference on Laser Peening
December 15-17, 2008 NASA-Johnson Space Center Houston, Texas, USA
Properties of treated materials
First International Conference on Laser Peening
December 15-17, 2008 NASA-Johnson Space Center Houston, Texas, USA
December 15-17, 2008 NASA-Johnson Space Center Houston, Texas, USA
INTRODUCTION
Laser Shock Processing is an innovative surface treatment, with which a short pulse laser produces elasto-plastic shifts at the atom level, which considerably increases densification of dislocations in the thin surface layer, which reflects mainly in modified mechanical properties. LSP produces shocks of motive quantity, which produce considerable densification of dislocations and generation of compressive residual stresses of high gradient (Grum et al., 2008). In practice, technologists and engineers frequently require the introduction of compressive residual stresses since the latter improves fatigue resistance of a material (Hammersley et al., 2000, Ocaa et al., 2004). LSP is frequently applied to exacting components, particularly in the aircraft industry for treatment of the most demanding components such as turbine spades of an aircraft F-16 Falcon and a bombardier F-22 Rockwell. In numerous studies Sano et al. (2002) confirmed the applicability of LSP, particularly because of improved material resistance to stress-corrosion cracking (SCC). Corrosion tests carried out in a vapour chamber for 500 hours confirmed an influence of LSP on increased material resistance to SCC. The same specimens were also used to perform a microscopic analysis, which confirmed the presence of cracks in the specimens in the as-delivered state whereas in the LSP-treated specimens no cracks were found. It has been found that a correct choice of the processing parameters provided desired variations of hardness and residual stresses in the surface of machine components can be achieved, which, in turn, provided improved material fatigue resistance.
激光熔覆涂层对高锰钢耐磨性能的影响

激光熔覆涂层对高锰钢耐磨性能的影响

材料研究与应用 2024，18（1）：157‐165Materials Research and ApplicationEmail ：clyjyyy@http ：//mra.ijournals.cn 激光熔覆涂层对高锰钢耐磨性能的影响韩纪鹏1,2,赵德刚1*,刘国祥2,张文彬2,陈小伟2（1.济南大学材料科学与工程学院，山东 济南 250022； 2.浙江武精机器制造有限公司，浙江 金华 321200）摘要： 使用FeCrVSi 和Ni+WC 涂层粉末，在高锰钢材料表面成功制备了激光熔覆涂层，并对涂层组织形貌、显微硬度和耐磨性进行了研究。

结果表明，两种涂层均可提升高锰钢基体的耐磨性和显微硬度，Fe‐CrVSi 涂层对基材性能的提升更佳，添加FeCrVSi 和Ni+WC 涂层的材料表面磨损量分别降低9.5%和6.3%，硬度分别为470—550 HV 和500—630 HV ，高于基体的250 HV ，这主要源于合金元素的固溶强化作用和激光熔覆过程的激冷效果。

在高应力载荷冲击过程中，涂层为高锰钢提供了第一层防护，以高硬度质点抵抗磨料破坏；同时，表层基材发生塑性变形和强化，产生形变诱导马氏体和栾晶硬化，提供了很高的硬化效应，在协同强化的作用下为高锰钢提供了更高的强度和硬度，提升了其耐磨性能。

关键词： 激光熔覆；高锰钢；涂层；耐磨性；碳化物；硬化效应；协同作用；激冷效果中图分类号：TG156；TB114 文献标志码： A 文章编号：1673-9981（2024）01-0157-09引文格式：韩纪鹏，赵德刚，刘国祥，等.激光熔覆涂层对高锰钢耐磨性能的影响［J ］.材料研究与应用，2024，18（1）：157-165.HAN Jipeng ，ZHAO Degang ，LIU Guoxiang ，et al.Influence of Laser Cladding Coating on Wear Resistance Property of High Mn Steel ［J ］.Materials Research and Application ，2024，18（1）：157-165.0　引言高锰钢具有优异的耐磨性能及较低的成本，广泛应用于矿山、机械、冶金、铁路、电力等行业中，如破碎机的衬板、动锥、定锥、锤头等。

17-4PH_不锈钢激光气体渗氮层显微组织与摩擦学性能

17-4PH_不锈钢激光气体渗氮层显微组织与摩擦学性能

第53卷第7期表面技术2024年4月SURFACE TECHNOLOGY·57·17-4PH不锈钢激光气体渗氮层显微组织与摩擦学性能刘礼1，邵磊1*，孙岩茹1，崔梓烁1，李克伟1，李文生2*（1.山东科技大学 材料科学与工程学院，山东 青岛 266590；2.西北师范大学 物理与电子工程学院，兰州 730070）摘要：目的提高17-4PH马氏体沉淀硬化不锈钢的表面硬度及耐磨性。

方法采用光纤激光器对17-4PH不锈钢进行激光气体氮化，采用不同激光功率在其表面制备渗氮层。

利用光学显微镜（OM）、电子扫描显微镜（SEM）和X射线衍射仪（XRD）等设备分析渗氮层的显微组织和相组成；借助显微硬度仪测试渗氮层截面深度方向的硬度；采用多功能摩擦磨损试验机测试基体、渗氮层的摩擦学性能，并通过SEM分析磨痕形貌，揭示基体与渗氮层的磨损机制。

结果在渗氮前样品组织为回火马氏体，经激光渗氮后样品表面形成了由板条马氏体组成的熔化区和回火马氏体组成的热影响区构成的渗氮层。

经渗氮后，样品的硬度均得到提高。

在激光功率3 000 W下，渗氮层的表面硬度最高，达到了415HV0.2，约是基体硬度的1.2倍，渗氮层的硬度随着深度的增加呈下降趋势，在深度为2.6 mm处其硬度与基体一致。

在回火马氏体向板条马氏体转变的相变强化，以及氮原子（以固溶方式进入基体）的固溶强化作用下，提高了渗氮层的硬度。

经渗氮后，样品的摩擦因数均高于基体，但渗氮后其磨损量相较于基体有所减少，在激光功率3 000 W下，其磨损体积最小，相较于基体减少了62%。

在激光功率2 500 W下马氏体转变不完全，在激光功率3 500 W下渗氮层出现了裂纹，都降低了渗氮层的硬度，其耐磨性也随之减小，且都略低于在3 000 W下。

磨损机制由渗氮前的以黏着磨损为主，转变为渗氮后的以磨粒磨损为主。

结论在17-4PH马氏体沉淀硬化不锈钢表面进行激光渗氮后，其表面硬度和耐磨性均得到提高，在激光功率3 000 W下制备的渗氮层具有较高的表面硬度和优异的耐磨性。