The influence of heat input on microstructure and porosity during laser cladding of Invar alloy

Zhan, Xiaoli; Qi, Chaoqi; Gao, Zhuanni; Tian, Deyong; Wang, Zhengdong

doi:10.1016/j.optlastec.2019.01.015

Cited by 59 publications

(22 citation statements)

References 19 publications

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“…Many columnar grains appeared around the transition layer, due to extreme undercooling at the bottom of the molten pool [23]. Meanwhile, the direction of columnar growth was basically perpendicular to the transition layer along the direction opposite to the thermal flow movement [8,13,23,24]. ese features of columnar grains and microstructures are basically independent of the laser scanning speed.…”

Section: Resultsmentioning

confidence: 96%

“…e thickness of the transition layer between the coating and HAZ decreased with increasing laser scanning speed, which resulted from the hindered element diffusion between the coatings and substrate at a shorter heating time during the laser cladding process [8,21,22]. Many columnar grains appeared around the transition layer, due to extreme undercooling at the bottom of the molten pool [23]. Meanwhile, the direction of columnar growth was basically perpendicular to the transition layer along the direction opposite to the thermal flow movement [8,13,23,24].…”

Section: Resultsmentioning

confidence: 99%

“…During the solidification process, the solidification phase transition occurred first at the bottom and then advanced to the top [28]. With continuous heating from the postsolidified metal droplets, the bottom microstructure grew coarsely [21,23], whereas the top microstructure solidified rapidly and had no time to grow more coarsely due to the cooling effects of the external environments [21,26]. Meanwhile, at low laser scanning speed (4 mm/s), there was enough time for the growth of carbides and borides, especially at the bottom, resulting in a higher microhardness of bottom coatings [3,28].…”

Section: Microhardness Measurementsmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Laser Scanning Speed on Microstructure, Microhardness, and Corrosion Behavior of Laser Cladding Ni45 Coatings

Qiao

Huang

et al. 2020

Journal of Chemistry

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The effects of laser scanning speed on the microstructure, microhardness, and corrosion behavior of Ni45 coatings were investigated by using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), microhardness, and electrochemical measurements. The results showed that increasing laser scanning speed promotes the transformation from planar crystals to dendrites and refines the grains concurrently. The γ-(Ni, Fe), FeNi3, and M23(C,B)6 are identified as the primary phase composition in the Ni45 coatings regardless of the laser scanning speed. Thereinto, the formation and growth of M23(C,B)6 precipitates can be inhibited with increasing laser scanning speed due to the higher cooling rate, which affects the microhardness distribution and corrosion resistance of the coating. On the one hand, the microhardness of the whole coating presents a downtrend with increasing laser scanning speed due to the reduction of M23(C,B)6 phase. On the other hand, the corrosion resistance in 0.5 M NaCl solution is improved to some extent at higher laser scanning speed because the less precipitation of M23(C,B)6 reduces the depletion of Cr around the precipitates. In contrast, all the coatings exhibit undifferentiated but poor corrosion resistance in the highly corrosive 0.5 M NaCl + 0.5 M H2SO4 solution.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Microhardness Measurementsmentioning

confidence: 99%

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Effects of Laser Scanning Speed on Microstructure, Microhardness, and Corrosion Behavior of Laser Cladding Ni45 Coatings

Qiao

Huang

et al. 2020

Journal of Chemistry

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“…This is so, because with the increase in E, liquid melt-pool gets more time and energy, which will help to create more porosity eventually, but due to the prolong time and more opening time of melt-pool, coalescence of small pores to form the bigger one is also carried out. Similar observations on the change in porosity attributes as a function of heat input, role of cooling rate on the restriction of gas movement out of the melt zone etc., have been reported in the literature [19,20,59]. It is interesting to note that as E is increased further from 0.487 kJ/mm to 0.526 kJ/mm, is decreased from 19 to 15.…”

Section: E Vs Different Micro-porosity Featuresmentioning

confidence: 60%

Study of Micro-porosity in Electron Beam Butt Welding

Das¹,

Dinda²,

Das³

et al. 2021

Preprint

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As complete elimination of porosity from the weld is very difficult, the next option available is to minimize this weld porosity, which is crucial for the safe performance of the welded components. However, this investigation through experiments alone is very tedious and time consuming. Additionally, very limited models are available in the literature for accurate prediction of different porosity attributes. The present study, thus, addressees both the experimental as well as modelling aspect on the study of micro-porosity during Electron Beam Welding (EBW) of SS304 plates. Welding parameters are reported to have significant influence on the micro-porosity. Hence, the influences of these parameters on micro-porosity attributes, namely pores number, average diameter, and sphericity are extensively studied experimentally employing optical microscopy (OM), scanning electron microscopy (SEM), X-ray computed tomography (XCT), and Raman spectroscopy. This is followed by an elaborate modelling through seven popular and well-recognized Machine Learning Algorithms (MLAs) namely, Multi-Layer Perceptron (MLP), Support Vector Regression (SVR), M5P model trees regression, Reduced Error Pruning Tree (REPTree), Random Forest (RF), Instance-based k-nearest neighbor algorithm (IBk) and Locally Weighted Learning (LWL). These different techniques enhance the chance of obtaining the better predictions of the said micro-porosity attributes by overcoming the effect of data-dependence and other limitations of individual MLAs. The different model-predicted micro-porosity data are also validated through experimental data. Statistical tests and Monte-Carlo reliability analysis are additionally utilized to evaluate the performances of the employed algorithms. IBk and MLP are overall found to perform well.

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“…With the reduction of the maximum temperature, the solid-state transformation temperature, elongation and impact energy increase, while the hardness decrease. Zhan et al [15] investigated the influences of heat input on the size, microstructure and porosity of cladding layers for Invar alloy through optical and scanning electron microscopy, electronic differential system (EDS). The results presented that the microstructure of cladding layers comprise elongate cellular crystals and equiaxed cellular crystals.…”

Section: Introductionmentioning

confidence: 99%

Microstructure evolution mechanism of single and multi-pass in laser cladding based on heat accumulation effect for invar alloy

Zhu

Chang³

et al. 2021

Int J Adv Manuf Technol

Self Cite

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This work explores how the process parameters in laser cladding affect the evolution of the microstructure of the single pass and multi-pass cladding layers of Invar alloys. The research examined the cladding layers from three aspects: (1) the transformation of grain size, HAZ width, ratio of the columnar crystal to the equiaxed crystal, and change of Fe content of cladding layer; (2) the effects of heat accumulation on grain size, HAZ width and remelting zone; and (3) the hardness distribution of single pass and multi-pass cladding layers. The investigation has the following four findings: (1) the cladding layer is composed of equiaxed crystals at the top and columnar crystals at the bottom of cladding layer; (2) the processing parameters have significant effects on the width of the HAZ, proportion between the columnar and equiaxed crystals and the change of Fe content of cladding layer.(3) the gradual accumulation of heat causes the increase in HAZ width, the grain size, and the area of the remelting zone; and (4) the hardness progressively reduces from the top to bottom along the direction of the centerline of the cladding layer.

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The influence of heat input on microstructure and porosity during laser cladding of Invar alloy

Cited by 59 publications

References 19 publications

Effects of Laser Scanning Speed on Microstructure, Microhardness, and Corrosion Behavior of Laser Cladding Ni45 Coatings

Effects of Laser Scanning Speed on Microstructure, Microhardness, and Corrosion Behavior of Laser Cladding Ni45 Coatings

Study of Micro-porosity in Electron Beam Butt Welding

Microstructure evolution mechanism of single and multi-pass in laser cladding based on heat accumulation effect for invar alloy

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