Effects of Scanning Speed on Microstructures and Properties of Laser Cladding Fe-Based Amorphous Composite Coatings

Qinglong, 鲁青龙 Lu; Yanfang, 王彦芳 Wang; Li, 栗荔 Li; Lijun, 肖丽君 Xiao; Xinmian, 李欣棉 Li; Zhiguo, 于治国 Yu; Zhiqiang, 石志强 Shi

doi:10.3788/cjl201340.0203007

Cited by 4 publications

(3 citation statements)

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“…被熔化，并快速凝固后形成稀释度极低且与基体成冶金结合的表面涂层。它可以显著改善基层表面的耐磨、耐蚀、耐热、抗氧化等性能，从而达到材料表面改性或破损修复的目的 [1][2][3] ，该技术已广泛应用于航空航天、汽车制造、重型机械、工业机床、生物医疗等领域，并创造了显著的经济效益。目前，激光熔覆技术的发展日渐成熟，但激光熔覆层的裂纹缺陷问题仍未得到很好地解决，这严重影响了产品的质量和寿命。研究表明，导致激光熔覆层产生裂纹的因素较多，其中主要与熔覆材料以及熔覆工艺参数选择的匹配度有关 [4][5] 。当材料选择不合适以及成形工艺匹配不佳时，由于材料的融化、凝固和冷却都是在极快的条件下进行的，容易在熔覆层的表面、体内以及熔覆层与基体的界面处形成裂纹。在激光熔覆的各工艺参数中，激光功率、光斑直径、熔覆速度、送粉速度、扫描速度和预热温度均会影响熔覆层裂纹的数目及开裂程度。文献 [6][7][8][9][10]分别研究了激光功率、熔覆速度、送粉速度和扫描速度对熔覆层裂纹的影响，并提出了一些控制裂纹的有效方法。朱贤刚等 [6]…”

Section: 引言激光熔覆技术通过运用强激光束辐照金属基体及其表面的涂层材料，使涂层材料和基体表面薄层同时unclassified

Influence of Laser Spot Diameter on Cladding Layer Cracking

Fuxing¹,

Gengrong²,

Xiaoxia³

et al. 2015

激光与光电子学进展

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The physical mechanism of crack formation in the process of laser cladding is analysed by theoretical derivation and the influence of laser spot diameter on crack defect is researched. The powder of Ni60 is cladded on the surface of base material (40Cr) by experiment and the characteristic of crack is analysed by observing the distributions of crack with optical microscope. The results show that the crack ratio of laser cladding layer is increasing gradually with the increase of spot diameter, in addition, the depth and width of crack are increasing obviously.

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Section: 引言激光熔覆技术通过运用强激光束辐照金属基体及其表面的涂层材料，使涂层材料和基体表面薄层同时unclassified

Influence of Laser Spot Diameter on Cladding Layer Cracking

Fuxing¹,

Gengrong²,

Xiaoxia³

et al. 2015

激光与光电子学进展

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“…In the literature [12], an alloy design criterion based on the XGBoost machine learning model was established to reveal the key characteristic parameters affecting the soft magnetic properties and thermal stability and to design a Fe-based soft magnetic amorphous alloy with excellent overall performance. In the literature [13], analyses were done on the organization and characteristics of the coating in relation to scanning speed. Fe 3 P and Fe 2 Siare two amorphous and crystalline phases that make up the majority of the coating.…”

Section: Introductionmentioning

confidence: 99%

Histological and mechanical properties of laser-melted carbon nanotube-toughened Fe-based amorphous coatings

Zhu

2023

Applied Mathematics and Nonlinear Sciences

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Laser melting technology is a new surface fabrication technique, and using laser beams to improve the mechanical properties of iron-based amorphous prepared by laser melting has become a hot topic in current materials research. Firstly, nickel-plated carbon nanotubes were used to improve the toughness of iron-based amorphous coatings, and nickel-plated carbon nanotubes were used to prepare iron-based amorphous composite fusion cladding layers. Then, the iron-based amorphous has good strength, strong wear resistance and corrosion resistance and is a good surface modification material. Finally, considering that the preparation of iron-based amorphous coating by laser melting technology can meet the preparation requirements of fast cooling of iron-based amorphous, the organization and mechanical properties of the iron-based amorphous coating are studied and analyzed by using laser melting technology. The results show that the toughness of the amorphous-1.00 wt% nickel-plated carbon nanotube composite clad layer is 7.67 MPa-m which is 33.4% higher than the amorphous clad layer. The composite clad layer with the addition of carbon nanotubes showed a significant increase in toughness without a significant decrease in hardness, and the prepared nickel-plated carbon nanotube/amorphous composite clad layer had better overall mechanical properties. This study improves the mechanical properties of iron-based amorphous coatings, which is important to improve the problems of decreasing service life and stability of equipment and components caused by corrosion and wear.

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“…Morphology of cross section 3.4 熔覆层的显微组织图 5 为激光功率为 1.5 kW，扫描速度为 150 mm/min，离焦量为 50 mm 时中 Al/Ti 熔覆层的显微组织，其中图 5(a)为 Al/Ti 为熔覆层的低倍显微组织。从图 5(a)中可以看出，熔池不同区域的组织各不相同，这是由于在激光扫描过程中熔池的温度梯度和凝固速率不一致，导致晶粒的生长方向发生改变。靠近熔池底部的温度梯度较大，结晶速度较小，此时晶粒在固液分界线处沿着温度梯度的垂直方向进行增长[14] ；靠近基体的液相温度梯度较大，晶粒来不及长大就凝固，因此熔池底部的晶粒以柱状晶为主，如图 5(c)所示。图 5(b)为熔覆层的扫描电子显微镜(SEM)图，从图中可以看出，从熔池底部到熔池顶部时，温度梯度逐渐减小，晶粒结晶速度逐渐升高，熔覆层中以胞状树枝晶为主。此时由于成分的过冷度较大，晶粒深入液相中进行生长，并向周围横向排出溶质，横向过冷导致二次横枝的形成 [3] 。 4 结论通过正交试验对激光熔覆过程中的工艺参数进行优化分析，获得当激光功率为 1.5 kW ，扫描速度为150mm/min，离焦量为 50 mm 时熔覆涂层质量较优。利用以上激光参数激光熔覆 Al/Ti 混合粉体，分析得到 51Al/Ti 熔覆层的显微组织。(a) 熔覆层的低倍形貌; (b) 熔覆层 SEM 图片; (c) 界面结合处 SEM 图片(激光功率 P=1.5 kW，扫描速度 V=150 mm/min，离焦量 S=50 mm) Microstructure of Al/Ti cladding layer. (a) Macro morphology of cladding layer; (b) SEM of cladding layer;(c) SEM of bond zone (laser power P=1.5 kW, scanning speed V=150 mm/min, defocusing amount S=50 mm)熔覆层的金相组织可知熔覆层组织以胞状树枝晶为主，且分布均匀细密。通过模拟计算 7050 铝合金上激光熔覆 Al/Ti 复合涂层，利用极差分析正交工艺下光斑中心最高温度数值得到：正交试验因素对中心点最高温度值影响程度从大到小的顺序是扫描速度 V，激光功率 P，离焦量 S。分析 9 组试样的熔池尺寸及不同位置点温度随时间的变化趋势可以得到，试样前端结合强度较差是由于熔覆过程中基体熔池深度较小，不足以使得基体与熔覆材料很好地结合，而后端都出现了不同程度的变形和烧蚀，是由于末端温度急剧积累引起的。参考文献…”

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