Double-Pass Laser Cladding Process for Small-Modulus Gear-Tooth Surface

Fig. 4. Microstructures of bottom of cladding layers at different power densities. (a) 24.4 kW·s·cm-2;(b) 26.5 kW·s·cm-2; (c) 31.8 kW·s·cm-2; (d) 35.8 kW·s·cm-2

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Fig. 5. Single-pass laser cladding coatings obtained with laser power density of 31.8 kW·s·cm-2.(a) Cross-sectional morphology of coating; (b) microstructure of coating; (c) macroscopic morphologies of coatings

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Fig. 6. Schematic of double-pass laser processing and its expected effect of target improvement

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Fig. 7. Schematic of laser processing by using two 1-mm spots

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Fig. 8. Schematic of laser processing by using two 1.5-mm spots

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Fig. 9. Cross-sectional morphologies of cladding layers under different processing techniques. (a) Large difference between power densities of double-pass laser spots; (b) small difference between power densities of double-pass laser spots

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Fig. 10. Cross-sectional microstructures of alloy coatings under different process parameters. (a) Input laser power density at tooth top of gear is greater than 12.72 kW·s·cm-2; (b) input laser power density at tooth bottom of gear is greater than 19.08 kW·s·cm-2; (c) input laser power densities at tooth top and bottom of gear are both 15.9 kW·s·cm-2

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Fig. 11. Comparison of penetration depths of cladding layers under different processing techniques. (a) Single-pass laser process parameters: P=250 W, u=0.5 mm/s, D=2 mm; (b) double-pass 1.5-mm laser process parameters: P=250 W, u1=1.67 mm/s, u2=1.12 mm/s, D=1.5 mm, η=40%; (c) double-pass 1 mm-laser process parameters: P=250 W, u1=2.5 mm/s, u2=1.67 mm/s, D=1 mm

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Fig. 12. Cross-sectional morphologies of nickel-based alloy cladding coatings under different processing techniques.(a) Single-pass laser processing; (b) double-pass laser lap processing; (c) double-pass laser independent processing

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Fig. 13. Hoadley heat input model[5]

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Fig. 14. Variation curves of liquid phase compositions in molten pool

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Fig. 15. XRD spectra of nickel-based alloy cladding coatings under different processing techniques. (a) Double-pass 1-mm laser spots; (b) double-pass 1.5-mm laser spots

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Fig. 16. Variation curves of cladding coatings' cross-sectional microhardness under different processing techniques

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Table 1. Processing parameters of single-pass laser cladding coatings on gear-tooth surface
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Table 1. Processing parameters of single-pass laser cladding coatings on gear-tooth surface
Number Scanning speed /(mm·s^-1) Power density /(kW·s·cm^-2)
1 0.75 21.2
2 0.70 22.7
3 0.65 24.4
4 0.60 26.5
5 0.55 28.9
6 0.50 31.8
7 0.45 35.3
8 0.40 39.7

Table 2. Cross-sectional dimensions and dilution rates of nickel-based alloy coatings on tooth surface at different power densities

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Table 2. Cross-sectional dimensions and dilution rates of nickel-based alloy coatings on tooth surface at different power densities

Number	Powerdensity /(kW·s·cm^-2)	Claddingmaximumheight /μm	Substratepenetrationdepth /μm	Coatingdilutionrate /%
1	21.2	947.12	0	0
2	22.7	989.20	0	0
3	24.4	1109.84	257.03	23.16
4	26.5	1324.35	337.53	25.48
5	28.9	1537.51	447.65	29.12
6	31.8	1627.21	562.04	34.54
7	35.3	1725.61	648.37	37.57
8	39.7	1749.89	698.21	39.90

Table 3. Power-density ratio of double-pass laser cladding with two 1-mm spots and scanning speed of each laser

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Table 3. Power-density ratio of double-pass laser cladding with two 1-mm spots and scanning speed of each laser

Number	Double beamenergy ratio	Power densityper beam /(kW·s·cm^-2)	Spot diameter /mm	Scanning speed perbeam /(mm·s^-1)
1	2∶8	P₁=6.36,P₂=25.44	1	u₁=5,u₂=1.25
2	3∶7	P₁=9.54,P₂=22.26	1	u₁=3.33,u₂=1.43
3	4∶6	P₁=12.72,P₂=19.08	1	u₁=2.5,u₂=1.67
4	5∶5	P₁=15.9,P₂=15.9	1	u₁=2,u₂=2

Table 4. Experimental parameters of double-pass laser cladding with two 1-mm spots
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Table 4. Experimental parameters of double-pass laser cladding with two 1-mm spots
Number Laser power /W Scanning speed perbeam /(mm·s^-1) Powder thickness /mm Double beamenergy ratio
1 250 u₁=5,u₂=1.25 1 2∶8
2 250 u₁=3.33,u₂=1.43 1 3∶7
3 250 u₁=2.5,u₂=1.67 1 4∶6
4 250 u₁=2,u₂=2 1 5∶5

Table 5. Cross-sectional morphology parameters of cladding layers under laser processing by using two 1-mm spots

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Table 5. Cross-sectional morphology parameters of cladding layers under laser processing by using two 1-mm spots

Number	Double beamenergy ratio	Gear tipheight /μm	Cladding maximumheight /μm	Dilution rateof coating /%	Bottom edge width ofalloyed area /μm
1	2∶8	517.37	1208.02	29.89	1564.62
2	3∶7	485.64	1068.11	28.93	1779.50
3	4∶6	460.61	961.72	27.28	1825.39
4	5∶5	426.44	1127.61	29.32	1912.43

Table 6. Experimental parameters of double-pass laser cladding with 1.5-mm spots

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Table 6. Experimental parameters of double-pass laser cladding with 1.5-mm spots

Number	Laser power /W	Scanning speedper beam /(mm·s^-1)	Powderthickness /mm	Double beamenergy ratio	Spot overlaprate /%
1	250	u₁=3.34,u₂=0.83	1	2∶8	30
2	250	u₁=2.22,u₂=0.95	1	3∶7	30
3	250	u₁=1.67,u₂=1.12	1	3∶7	30
4	250	u₁=1.33,u₂=1.33	1	5∶5	30
5	250	u₁=3.34,u₂=0.83	1	2∶8	40
6	250	u₁=2.22,u₂=0.95	1	3∶7	40
7	250	u₁=1.67,u₂=1.12	1	3∶7	40
8	250	u₁=1.33,u₂=1.33	1	5∶5	40
9	250	u₁=3.34,u₂=0.83	1	2∶8	50
10	250	u₁=2.22,u₂=0.95	1	3∶7	50
11	250	u₁=1.67,u₂=1.12	1	3∶7	50
12	250	u₁=1.33,u₂=1.33	1	5∶5	50

Table 7. Cross-sectional morphology parameters of cladding layers under laser processing by using two 1.5-mm spots

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Table 7. Cross-sectional morphology parameters of cladding layers under laser processing by using two 1.5-mm spots

Number	Double beam power densityratio and spot overlap ratio	Gear tipheight /μm	Cladding maximumheight /μm	Dilution rateof coating /%	Bottom edge widthof alloyed area /μm
1	Energy ratio of 5∶5, overlap of 30%	403.29	1408.31	32.77	1917.12
2	Energy ratio of 4∶6, overlap of 40%	427.53	1366.44	31.48	1878.77
3	Energy ratio of 5∶5, overlap of 40%	414.37	1402.73	32.45	1815.64
4	Energy ratio of 3∶7, overlap of 50%	436.57	1446.28	32.51	1633.46
5	Energy ratio of 4∶6, overlap of 50%	428.25	1493.69	32.87	1677.82
6	Energy ratio of 5∶5, overlap of 50%	408.46	1520.81	33.59	1714.03

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Gancheng Liu, Bo Huang. Double-Pass Laser Cladding Process for Small-Modulus Gear-Tooth Surface[J]. Chinese Journal of Lasers, 2019, 46(10): 1002009

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Paper Information

Category: laser manufacturing

Received: Apr. 18, 2019

Accepted: Jun. 13, 2019

Published Online: Oct. 25, 2019

The Author Email: Liu Gancheng (liugcmail@126.com)

DOI:10.3788/CJL201946.1002009

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Processing parameters of single-pass laser cladding coatings on gear-tooth surface

Table 1. Processing parameters of single-pass laser cladding coatings on gear-tooth surface

Table 2. Cross-sectional dimensions and dilution rates of nickel-based alloy coatings on tooth surface at different power densities

Table 2. Cross-sectional dimensions and dilution rates of nickel-based alloy coatings on tooth surface at different power densities

Table 3. Power-density ratio of double-pass laser cladding with two 1-mm spots and scanning speed of each laser

Table 3. Power-density ratio of double-pass laser cladding with two 1-mm spots and scanning speed of each laser

Table 4. Experimental parameters of double-pass laser cladding with two 1-mm spots

Table 4. Experimental parameters of double-pass laser cladding with two 1-mm spots

Table 5. Cross-sectional morphology parameters of cladding layers under laser processing by using two 1-mm spots

Table 5. Cross-sectional morphology parameters of cladding layers under laser processing by using two 1-mm spots

Table 6. Experimental parameters of double-pass laser cladding with 1.5-mm spots

Table 6. Experimental parameters of double-pass laser cladding with 1.5-mm spots

Table 7. Cross-sectional morphology parameters of cladding layers under laser processing by using two 1.5-mm spots

Table 7. Cross-sectional morphology parameters of cladding layers under laser processing by using two 1.5-mm spots