Experimental investigation into weld cladding of Ni-WC MMC overlays by CMT process

doi:10.21203/rs.3.rs-1556833/v1

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Experimental investigation into weld cladding of Ni-WC MMC overlays by CMT process

https://doi.org/10.21203/rs.3.rs-1556833/v1

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In the search for versatile and effective weld cladding processes to deposit ultra-wear-resistant Ni-WC MMC (Ni-based tungsten carbide metal matrix composite) overlays for mining applications, there is an increasing interest in exploring advanced low-heat-input cold metal transfer (CMT) method. Depositions of single weld bead tracks of Ni-WC MMCs on steel plates were performed by employing CMT process; Taguchi design of experiments was used to plan the experimental investigation. All weld tracks exhibit continuous and uniform bead profile and sound metallurgical bonding to the substrate. Retained WCs are present in the overlay tracks relatively uniformly. Formation of primary WC and secondary carbides is observed depending on the level of dilution. In contrast to traditional gas metal arc welding (GMAW) processes, volume fraction of retained WC (f_WC) is not directly correlated with heat input for CMT process, and can reach a high level together with improved weld bead appearance at high deposition rate. f_WC is negatively correlated with dilution rate. Deposition rate has a positive correlation with average instantaneous power, which is, in turn, positively correlated with wire feed speed. Addition of oxygen into shielding gas mixtures promotes carbide transfer from cored feed wire to the weld track and increases f_WC. Analysis of Signal-to-Noise ratios shows that it is difficult to find a single set of optimized process control parameters, and trade-offs are needed in the engineering practice. The present investigation demonstrates that CMT process has a clear advantage for depositing Ni-WC MMC overlays over traditional GMAW technologies and that Taguchi method is a powerful tool in process improvement for weld cladding of Ni-WC MMC overlays.

Weld cladding

Cold Metal Transfer (CMT)

carbide transfer efficiency

retained WC

carbide dissolution

Taguchi design of experiments

Table 1 Chemical composition of ASTM A36 steel [34]

[wt.%]	C	P	S	Si	Cu	Fe
ASTM A36	0.26	0.04	0.05	0.4	0.20	Bal.

Table 2 Tubular cored wire specification [35]

Electrode commercial name

Supplier

Nominal composition

Nominal Hardness

COR®FACE 164 MC

COR-MET

NiCrBSi- 55 wt.% WC

Matrix=38-42 HRC

WC = 2600 Knoop

Table 3 Preset waveform values for chosen WFS

Symbol	Unit	Definition	Synergic WFS guideline [m/min]
Symbol	Unit	Definition	2.1	3.9	5.7	7.5
*I_w*	[A]	Current setpoint for wait phase, until the wire is immersed in the weld pool	35	60	82	110
*I_sc*	[A]	Current setpoint in the short-circuit phase	35	40	73	110
*I_b*	[A]	Current setpoint in the boost phase	225	290	307	340
*t_b*	[ms]	Maximum duration of the boost phase	3	3.75	5.13	5.6

Table 4 Taguchi L16 factors and levels

Std. order	WFS (m/min)	Travel Speed (m/min)	Shielding gas (%, Ar-balanced)
1	2.1	0.3	25% CO₂
2	2.1	0.4	15% CO₂
3	2.1	0.5	2% O₂
4	2.1	0.6	5% O₂
5	3.9	0.3	15% CO₂
6	3.9	0.4	25% CO₂
7	3.9	0.5	5% O₂
8	3.9	0.6	2% O₂
9	5.7	0.3	2% O₂
10	5.7	0.4	5% O₂
11	5.7	0.5	25% CO₂
12	5.7	0.6	15% CO₂
13	7.5	0.3	5% O₂
14	7.5	0.4	2% O₂
15	7.5	0.5	15% CO₂
16	7.5	0.6	25% CO₂

Table 5 Measured values of the tubular cored wire samples, used to calculate the initial carbide volume fraction

Measured parameters	Sample 1	Sample 2	Sample 3	Sample 4	Sample 5	Average
Sample length [mm]	96.54	102.12	106.70	97.52	101.43	100.86
Electrode weight [g]	1.631	1.739	1.821	1.658	1.705	1.711
Powder weight [g]	0.892	0.958	0.995	0.904	0.921	0.934
**l_m[g/mm]**	0.0169	0.0170	0.0171	0.0170	0.0168	0.0170
**A_{Ni sheath}[mm²]**	0.792	0.808	0.835	0.830	0.830	0.819
**Wt_p[%]**	54.68	55.08	54.63	54.52	54.01	54.58

Table 6 Summary of the selected goal for quality criteria of the overlay and corresponding S/N ratio formula

Quality criterion

Goal of experiments

S/N ratio^* formula

f_WC

Deposition rate

W/H

Larger-the-better

(maximize the response)

Dilution

Smaller-the-better

(minimize the response)

n = number of response's observations in each experiment

Y_i=observed measurement for each response

^a The unit of the S/N ratio is decibels-isotropic (dBi)

Table 7 EDS spot measurement results of marked locations in Fig. 6

Elements (wt.%)	Point
Elements (wt.%)	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19
C	6.16	3.68	9.11	8.98	9.55	5.87	10.56	5.57	9.44	11.23	12.91	11.49	7.84	9.05	9.22	5.41	11.39	11.84	14.5
O	0.12	2.34	0.55	0.39	0.76	0.05	0.77	0.71	0.00	1.41	1.02	1.49	2.04	1.09	0.88	0.31	1.82	1.33	0.95
Si	0.04	0.18	0.00	90.11	0.00	0.16	88.37	0.08	0.06	0.39	0.00	0.00	0.33	1.36	0.00	0.39	3.72	85.21	84.29
Cr	0.24	93.61	0.09	0.00	0.00	0.00	0.03	0.00	0.01	0.03	0.06	0.01	0.07	0.09	0.04	0.00	0.00	0.05	0.00
Fe	0.14	0.06	0.21	0.00	0.03	0.13	0.00	0.06	0.05	0.21	0.14	0.24	0.24	0.02	0.52	0.13	4.54	0.00	0.00
Ni	93.3	0.13	0.09	0.51	0.02	93.79	0.28	93.59	90.31	83.56	0.17	0.15	86.82	0.88	0.26	89.96	1.06	0.25	0.25
W	0.00	0.00	89.95	0.00	89.63	0.00	0.00	0.00	0.14	3.16	85.71	86.61	2.66	87.52	89.09	3.8	77.47	1.31	0.00

Table 8 EDS spot measurement results of marked locations in Fig. 7

Elements (wt.%)	Point
Elements (wt.%)	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16
C	7.58	15.88	7.34	8.52	10.38	6.07	9.97	12.37	16.23	16.28	2.33	9.51	18.1	5.87	7.63	7.7
O	7.40	18.93	6.50	10.7	13.73	3.21	6.38	1.74	5.9	13.02	10.86	16.07	14.2	11.83	9.76	8.3
Si	0.50	1.62	1.24	4.19	1.30	1.14	1.39	0.00	0.35	5.19	2.75	2.19	2.8	0.25	0.74	1.76
Cr	0.10	0.29	0.57	0.77	0.56	0.25	0.27	0.00	0.11	0.17	0.5	0.32	0.45	0.06	0.08	0.85
Fe	0.54	39.16	2.18	1.86	1.56	0.67	0.60	0.35	0.35	0.75	1.48	0.83	1.3	0.18	0.43	2.07
Ni	6.06	21.37	79.18	60.54	69.87	77.05	78.89	3.75	7.55	20.44	65.04	21.34	36.08	3.04	5.96	69.86
W	77.81	2.77	2.98	13.4	2.59	11.61	2.51	81.79	69.51	44.16	17.06	49.74	27.07	78.76	75.4	9.47

Table 9 Experimental results

ID	WFS [m/min]	TS^a [m/min]	SG^b[%]	I_avg [A]	V_avg[V]	HI [kJ/mm]	AIP [kW]	f_WC [%]	h [%]	Dil.^c[%]	P [mm]	DR^d [kg/hr]	W [mm]	H [mm]	W/H	q [°]
1	2.1	0.3	25% CO₂	62.89	10.53	0.19	0.93	25.2	67.1	0.92	0.04	1.20	3.84	2.17	1.77	80
2	2.1	0.4	15% CO₂	64.38	10.46	0.15	0.98	26.8	71.4	1.05	0.07	1.30	3.37	2.02	1.67	85
3	2.1	0.5	2% O₂	64.37	8.97	0.10	0.85	20.7	55.5	1.65	0.09	1.28	1.92	2.06	0.93	122
4	2.1	0.6	5% O₂	63.45	9.33	0.09	0.87	24.5	65.4	0.88	0.06	1.28	3.35	1.46	2.30	71
5	3.9	0.3	15% CO₂	94.78	10.90	0.29	1.46	25.7	74.2	8.52	0.27	1.87	7.10	2.05	3.47	49
6	3.9	0.4	25% CO₂	93.09	12.03	0.25	1.66	20.7	64.2	14.83	0.25	1.89	6.82	1.68	4.05	41
7	3.9	0.5	5% O₂	91.24	9.82	0.16	1.36	23.0	65.2	6.77	0.15	2.01	6.00	1.67	3.60	50
8	3.9	0.6	2% O₂	92.39	9.33	0.13	1.32	18.6	52.4	6.57	0.18	1.95	5.35	1.60	3.34	49
9	5.7	0.3	2% O₂	127.78	9.46	0.35	1.75	27.5	78.0	6.93	0.19	2.40	7.70	2.28	3.37	49
10	5.7	0.4	5% O₂	129.84	10.12	0.28	1.89	22.4	68.3	13.64	0.35	2.50	7.93	1.83	4.34	36
11	5.7	0.5	25% CO₂	140.47	12.68	0.30	2.54	18.9	62.8	20.72	0.29	2.55	6.92	1.56	4.43	34
12	5.7	0.6	15% CO₂	139.90	11.75	0.24	2.36	12.0	38.1	16.99	0.37	2.79	7.66	1.57	4.88	32
13	7.5	0.3	5% O₂	166.34	10.30	0.47	2.34	26.3	77.4	10.08	0.42	3.03	9.86	2.40	4.11	43
14	7.5	0.4	2% O₂	165.06	9.39	0.32	2.14	26.2	78.1	11.67	0.32	3.04	7.99	2.18	3.67	49
15	7.5	0.5	15% CO₂	177.05	11.77	0.34	2.86	18.2	60.7	20.83	0.55	3.40	9.83	1.78	5.52	30
16	7.5	0.6	25% CO₂	173.29	12.27	0.29	2.95	10.3	34.1	20.26	0.44	3.15	8.64	1.58	5.46	27

^a travel speed; ^b shielding gas (Ar-balanced); ^c dilution; and ^d deposition rate

Table 10 EDS spot results of marked locations in Fig. 13

Elements (wt.%)	Point
Elements (wt.%)	1	2	3	4	5	6	7	8	9	10	11	12	13	14
C	7.48	6.10	19.84	20.48	18.67	20.79	51.15	14.71	19.47	20.62	19.78	19.31	4.44	4.58
O	0.00	0.00	0.11	0.23	0.11	0.00	0.00	0.37	0.00	0.00	0.01	0.13	0.00	0.00
Si	0.00	0.00	0.00	0.00	0.00	0.00	0.02	0.00	0.00	0.00	0.00	0.00	0.00	0.59
Cr	0.99	0.56	1.49	1.63	1.48	0.99	0.56	1.33	1.75	3.66	0.09	1.27	0.98	2.23
Fe	4.92	5.31	0.28	0.37	0.54	0.35	3.57	0.28	0.41	0.3	0.17	0.19	1.39	1.30
Ni	73.94	73.02	6.40	7.75	13.5	8.73	42.00	4.3	9.54	15.4	3.2	5.67	75.53	77.49
W	12.67	15.01	71.88	69.54	65.7	69.14	2.71	79.00	68.83	60.03	76.75	73.42	17.66	13.81

Table 11 EDS point results of marked locations in Fig. 15

Elements (wt.%)	Point
Elements (wt.%)	1	2	3	4	5	6	7	8	9	10	11
C	4.31	5.87	15.68	17.00	13.65	11.75	16.45	16.41	15.91	3.57	3.99
O	0.18	0.00	0.00	0.00	0.36	0.02	0.00	0.00	0.00	0.00	0.00
Si	0.01	0.30	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.16	0.36
Cr	0.83	1.93	1.99	0.93	2.05	3.83	3.14	4.00	3.52	0.98	1.48
Fe	13.60	11.57	3.80	2.52	2.67	3.81	2.70	2.18	2.22	9.00	7.92
Ni	65.98	61.29	15.88	11.58	7.58	12.19	16.69	13.56	14.96	72.25	74.19
W	15.09	19.03	62.66	67.98	73.68	68.4	61.02	63.85	63.39	14.05	12.06

Table 12 EDS point results of the marked locations in Fig. 17

Elements (wt.%)	Point
Elements (wt.%)	1	2	3	4	5	6	7	8	9	10	11	12	13	14
C	10.17	6.35	3.78	15.12	16.16	16.74	17.71	15.89	18.17	19.21	2.9	3.11	16.5	16.29
O	0.17	0.03	0.44	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.18	0.00	0.20	0.45
Si	0.00	0.17	0.15	0.00	0.00	0.00	0.00	0.25	0.00	0.00	0.31	0.45	0.00	0.00
Cr	0.83	1.02	0.66	1.06	0.90	1.23	1.39	1.41	3.46	3.92	0.87	1.19	3.32	3.24
Fe	21.46	23.3	24.60	7.78	8.07	8.87	7.98	9.56	3.67	2.78	16.16	13.55	2.96	2.80
Ni	49.88	62.45	61.50	47.3	47.59	36.14	29.56	45.74	13.34	7.01	67.34	73.51	10.55	7.69
W	17.48	6.67	8.87	28.74	27.27	37.02	43.36	27.15	61.36	67.08	12.24	8.19	66.47	69.52

Table 13 EDS point results of marked locations in Fig. 19

Elements (wt.%)	Point
Elements (wt.%)	1	2	3	4	5	6	7	8	9	10	11	12	13
C	16.61	13.92	13.82	7.63	15.73	15.32	19.88	18.41	15.35	16.46	15.86	5.58	6.68
O	0.00	0.41	0.27	0.15	0	0.02	0.37	0.29	0.74	0.17	0.07	0.26	0.04
Si	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.03	0.53
Cr	1.10	1.38	1.45	0.95	1.11	0.87	0.85	1.22	1.26	1.39	1.13	0.68	1.14
Fe	5.67	4.51	4.19	17.86	6.57	4.87	1.55	1.60	1.79	8.16	11.06	22.54	22.31
Ni	12.49	7.88	7.08	41.35	15.36	11.88	2.79	2.58	2.94	17.44	25.39	58.53	58.86
W	64.13	71.91	73.19	32.07	61.22	67.04	74.56	75.89	77.92	56.38	46.49	12.38	10.44

Table 14 S/N ratio results of the experiments

ID	WFS [m/min]	Travel speed [m/min]	Shielding gas [%]	S/N ratio [dBi]
ID	WFS [m/min]	Travel speed [m/min]	Shielding gas [%]	f_WC	h	Dilution	P	Deposition rate	W/H
1	2.1	0.3	25% CO₂	28.37	36.86	2.63	-31.39	1.55	4.94
2	2.1	0.4	15% CO₂	28.06	36.65	-4.95	-36.98	2.19	4.40
3	2.1	0.5	2% O₂	26.90	35.49	-5.87	-39.01	2.09	-0.63
4	2.1	0.6	5% O₂	27.92	36.54	-6.74	-35.49	2.10	6.89
5	3.9	0.3	15% CO₂	27.48	36.83	-19.91	-48.64	5.44	10.81
6	3.9	0.4	25% CO₂	26.69	36.31	-22.20	-47.92	5.53	12.15
7	3.9	0.5	5% O₂	27.87	36.98	-17.62	-43.83	6.05	11.12
8	3.9	0.6	2% O₂	25.45	34.47	-16.52	-44.98	5.78	10.48
9	5.7	0.3	2% O₂	28.99	38.02	-16.49	-45.68	7.56	10.54
10	5.7	0.4	5% O₂	28.01	37.75	-22.91	-50.94	7.96	12.63
11	5.7	0.5	25% CO₂	25.99	36.08	-24.76	-49.56	7.89	12.81
12	5.7	0.6	15% CO₂	21.79	31.98	-25.24	-51.47	8.88	13.77
13	7.5	0.3	5% O₂	27.77	37.54	-23.07	-52.75	9.61	12.27
14	7.5	0.4	2% O₂	28.29	37.69	-20.61	-50.20	9.63	11.29
15	7.5	0.5	15% CO₂	24.87	35.34	-26.35	-54.86	10.62	14.83
16	7.5	0.6	25% CO₂	21.10	31.51	-26.16	-52.82	9.91	14.72

Table 15 Taguchi's recommended process control parameters to improve the quality of Ni-WC MMC overlays

Quality criterion	Recommended process control parameter				Remark
Quality criterion	WFS [m/min]	Travel speed [m/min]	Shielding gas [%]	Predicted S/N [dBi]	Remark
f_WC	2.1	0.3	5% O₂	30.66	The recommended parameters are disadvantageous for deposition rate, and W/H
h	2.1	0.3	5% O₂	38.89
Dilution	2.1	0.3	2% O₂	1.78
P	2.1	0.3	2% O₂	-33.24
Deposition rate	7.5	0.6	15% CO₂	10.24	Disadvantageous for f_WC, h, dilution and P
W/H	7.5	0.6	25% CO₂	15.58	Disadvantageous for f_WC, h, dilution and P

Table 16 Selected confirmation tests to improve the quality of Ni-WC MMC overlays by prioritizing f_WC andh

Confirmation test	WFS [m/min]	Travel speed [m/min]	Shielding gas [%]	S/N ratio of f_WC			S/N ratio of h
Confirmation test	WFS [m/min]	Travel speed [m/min]	Shielding gas [%]	Predicted [dBi]	Experimental [dBi]	Error [%]	Predicted [dBi]	Experimental [dBi]	Error [%]
V1	2.1	0.3	5% O₂	30.66	27.07	6.78	38.89	35.59	4.82
V2	3.9	0.3	5% O₂	29.73	28.71	3.43	38.66	37.77	2.30

Table 17 Confirmation test results

WFS [m/min]

TS^a[m/min]

SG^b[%]

I_avg [A]

V_avg

[V]

HI [kJ/mm]

AIP [kW]

f_WC

[%]

Dil.^c[%]

P
[mm]

DR^d [kg/hr]

W
[mm]

H
[mm]

W/H

q
[°]

2.1

0.3

5% O₂

60.15

9.14

0.16

0.79

27.06

71.34

1.01

52.67

1.15

2.91

2.27

1.29

96.33

3.9

0.3

5% O₂

88.33

9.67

0.26

1.28

27.29

77.46

7.10

184.00

1.87

6.91

2.18

3.17

56.83

^a travel speed; ^b shielding gas (Ar-balanced); ^c dilution; and ^d deposition rate

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Reviewers agreed at journal
18 May, 2022
Reviews received at journal
11 May, 2022
Reviewers invited by journal
18 Apr, 2022
Editor assigned by journal
18 Apr, 2022
First submitted to journal
13 Apr, 2022

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Experimental investigation into weld cladding of Ni-WC MMC overlays by CMT process

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