李金华,李高松,张德强,陈翔.激光熔覆 NJ-4 镍基合金涂层显微硬度的探究[J].表面技术,2018,47(8):77-83.
LI Jin-hua,LI Gao-song,ZHANG De-qiang,CHEN Xiang.Study on Microhardness of Laser Cladding NJ-4 Powder[J].Surface Technology,2018,47(8):77-83
激光熔覆 NJ-4 镍基合金涂层显微硬度的探究
Study on Microhardness of Laser Cladding NJ-4 Powder
投稿时间:2018-01-04  修订日期:2018-08-20
DOI:10.16490/j.cnki.issn.1001-3660.2018.08.012
中文关键词:  过冷度  晶体尺寸  NJ-4 合金粉末  形核率  晶体长大速度  结构组织
英文关键词:super cool  crystal size  NJ-4 alloy powder  nucleation rate  crystal growth rate  structure organization
基金项目:辽宁省自然科学基金项目(201602371);辽宁省教育厅项目(L2015231)
作者单位
李金华 辽宁工业大学 机械工程与自动化学院,辽宁 锦州 121001 
李高松 辽宁工业大学 机械工程与自动化学院,辽宁 锦州 121001 
张德强 辽宁工业大学 机械工程与自动化学院,辽宁 锦州 121001 
陈翔 辽宁工业大学 机械工程与自动化学院,辽宁 锦州 121001 
AuthorInstitution
LI Jin-hua School of Mechanical Engineering and Automation, Liaoning University of Technology, Jinzhou 121001, China 
LI Gao-song School of Mechanical Engineering and Automation, Liaoning University of Technology, Jinzhou 121001, China 
ZHANG De-qiang School of Mechanical Engineering and Automation, Liaoning University of Technology, Jinzhou 121001, China 
CHEN Xiang School of Mechanical Engineering and Automation, Liaoning University of Technology, Jinzhou 121001, China 
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中文摘要:
      目的 探究晶体尺寸、组织结构和过冷度对 NJ-4 镍基合金涂层显微硬度的影响规律,找出一定组织结构和晶体尺寸下的最佳显微硬度。方法 采用正交实验对基体进行激光熔覆,然后分析组织结构、晶体尺寸和过冷度对合金涂层硬度的影响。结果 不同组织结构的 NJ-4 镍基合金涂层显微硬度有很大差异。从熔覆层的上表面到下表面依次为树枝晶、等轴晶、胞状枝晶、等轴晶、树枝晶、板条状马氏体。晶体结构依次变化时,显微硬度先增大、后减小、再增大,在熔覆层上部的等轴晶处的显微硬度最大。此外显微硬度还受到晶体尺寸和过冷度的影响。激光为熔池凝固提供特殊的冷却环境,抑制了凝固过程中杂质的析出,降低了缺陷的产生概率,提高了熔覆层硬度。激光熔覆层产生的板条状马氏体镶嵌在基体和熔覆层之间,提高了冶金结合强度,测量发现熔覆层的显微硬度是基体的 2.5 倍以上。结论 熔覆层的显微硬度最终由组织结构、晶体尺寸和过冷度决定。
英文摘要:
      The work aims to study the influence of crystal size, structure and super-cooling on the microhardness of NJ-4 alloy coating and find out the optimum microhardness of the structure and crystal size. Orthogonal experiment was used to carry out laser cladding to the substrate. Then, the influence of structure crystal size and super-cooling degree on hardness of alloy coating was analyzed. From the results, the microhardness of different tissue structures was very different. Dendrite crystal, equiaxed crystal, cellular crystal, equiaxed crystal, dendrite crystal and banded martensite were respectively distributed from the upper surface to the lower surface of cladding layer. When the crystal structure changed in turn, the microhardness firstly increased, then decreased and finally increased again. The microhardness was greatest in the equiaxial crystals at the upper part of the cladding layer. The microhardness was also affected by crystal size and overcooling. The special cooling environment provided by the laser for solidification of molten pool inhibited the precipitation of impurities in solidification process and reduced the production probability of defects to improve the hardness of the cladding layer. The lamellar martensite produced by the laser cladding layer was inlaid between the substrate and the cladding layer and improved the metallurgical bonding strength. Through the measurement, the microhardness of the cladding layer was more than 2.5 times of that in the substrate. The micro- hardness is determined by the structure, crystal size and the degree of supercooling.
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