Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第30卷    第4期    总第253期    2020年4月

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文章编号:1004-0609(2020)-04-0817-12
TC4钛合金不同气源激光渗氮行为
李文生1,张文斌1,武彦荣2,梁 刚2,高凤琴1,石 玗1,俞伟元1,姚小春1

(1. 兰州理工大学 有色金属先进加工与再利用国家重点实验室,兰州 730050;
2. 东方电气集团 东方汽轮机有限公司,德阳 618000
)

摘 要: 在用矩形光斑高功率半导体激光器,在纯氮气和氮氩混合两种不同方式下,通过不同气流量和氮氩混合对Ti-6Al-4V进行表面渗氮,研究气体流量、氮氩混气比对渗氮熔池形态及渗氮组织和力学性能的影响。采用SEM、EDS以及XRD对渗氮层的显微组织、微区成分及相组成进行研究。结果表明:采用纯氮渗氮时,在15 L/min气流量下获得均匀渗氮层,继续增大气流量渗氮熔池流动紊乱,出现贯穿裂纹,且渗氮深度和硬度并未随气流量增加;采用不同氮氩混气比渗氮时,渗氮层的表层硬度均较相同条件下纯氮气渗氮层的有所降低,且渗氮层裂纹倾向减弱,渗氮层组织由表至里在200~800 μm内按层深依次存在TiN0.88、TiN0.61、TiN0.3三种稳定相;分别采用纯氮气和不同氮氩混气比渗氮时,渗氮层组织沿层深分布依次均为粗短树枝晶、等轴晶、细长树枝晶、针状晶。

 

关键字: 激光渗氮;气体流量;裂纹;组织

Laser nitriding behavior of Ti-6Al-4V with different gas sources
LI Wen-sheng1, ZHANG Wen-bin1, WU Yan-rong2, LIANG Gang2, GAO Feng-qin1, SHI Yu1, YU Wei-yuan1, YAO Xiao-chun1

1. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China;
2. Dongfang Turbine Co., Ltd., Dongfang Electric Corporation, Deyang 618000, China

Abstract:In two different ways of pure nitrogen and nitrogen argon mixing, a rectangular spot high-power semiconductor laser was used to nitride on surface of Ti-6Al-4V under different gas flow rates and nitrogen to argon mixture ratios. The effects of gas flow rates and gas mixture ratio of nitrogen to argon on nitriding molten pool morphology, nitriding microstructure and mechanical properties were studied. The microstructure, composition and phase composition of nitriding layer were studied by scanning electron microscopy(SEM), energy dispersion(EDS) and X-ray diffractometry(XRD). The results show that the uniform nitriding layer is obtained at pure nitrogen gas flow rate of 15 L/min. Continue to increase the gas flow, the flow of the nitriding molten pool is turbulent and the through cracks appear. The depth and hardness of the nitriding do not increase with the gas flow. When nitriding with different gas mixture ratios of nitrogen to argon, the surface hardness of the nitriding layer is lower than that of the nitriding layer at pure nitrogen nitriding, and the cracking tendency of the nitriding layer is weakened. The microstructure of the nitriding layer is three stable phases of TiN0.88, TiN0.61, TiN0.3 according to the layer depth in the range of 200 to 800 μm from the surface to the inner. Under pure nitrogen and different gas mixture ratios of nitrogen to argon for nitriding, the microstructure of nitriding layer is composed of coarse short dendrite, equiaxed grain, slender dendrite, fine needle-shaped grain, respectively.

 

Key words: laser nitriding; gas flow rate; cracks; microstructure

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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