Table 1
Sample code and the PSD of powders [32].
| Feedstock material | Sample code | PSD (μm) |
|---|---|---|
| 316L | S1 | −150 + 45 |
| NiCrBSi | S2 | −125 + 45 |
| NiCrBSi + 35 wt% WC | S3 | −125 + 22 |
| NiCrCuMo | S4 | −125 + 45 |
Table 2
Chemical composition of feedstock powders (material no. from Table 1).
| Feedstock | Elemental content (wt%) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| C | Si | Cr | B | Ni | Mo | Cu | Fe | W | |
| S1 | 0.03 | — | 18.00 | — | 13.00 | 2.7 | — | bal. | — |
| S2 | 0.95 | 3.80 | 16.50 | 3.30 | Bal. | — | — | — | — |
| S3 | 2.35 | 3.80 | 16.50 | 3.30 | Bal. | — | — | — | 25.00 |
| S4 | 0.50 | 4.00 | 16.00 | 4.00 | Bal. | 3.0 | 3.0 | — | — |
Table 3
Parameters used for hardfacing of the overlays.
| Sample code | Parameters | ||
|---|---|---|---|
| Current intensity (A) | Torch speed (mm/s) | Powder feed rate (g/min) | |
| S1 | 100 | 0.8 | 9.7 |
| S2 | 80 | 0.8 | 9.0 |
| S3 | 100 | 1.6 | 11.0 |
| S4 | 80 | 0.8 | 9.0 |
Figure 1
OM images after 3% nital etching of the interface line (cross-section): reference material S1 (a), S2 (b and c), S3 (d and e), and S4 (f and g).
Figure 2
Cross-sections of the hardfacing layers at lower magnifications (200×) (S2 (a), S3 (c), and S4 (e)) and higher magnifications (500×) (S2 (b), S3 (d), and S4 (f)).
Figure 3
Top view SEM images of tested materials before the electrochemical corrosion (S2 (a), S3 (c), and S4 (e)) and after the process (S2 (b), S3 (d), and S4 (f)); magnification: 1,000×.
Figure 4
SEM images of the cross-section of S2 (a), S3 (c), and S4 (e) samples. EDS spectra of the characteristic obtained from the surface of S2 (b), S3 (d), and S4 (f) samples.
Figure 5
Representative potentiodynamic polarization curves of hardfacing layers examined in 3.5% NaCl solution.
Table 5
Electrochemical parameters obtained for all samples.
| Sample code | E OC (mV) | E corr vs Ag/AgCl (mV) | I corr (µA/cm2) | R p (kΩ cm2) | E p (mV) |
|---|---|---|---|---|---|
| Average result | |||||
| S1 | −87.8 | −159.7 | 0.1 | 213.7 | 845 |
| S2 | −262.0 | −290.9 | 0.3 | 108.8 | 535 |
| S3 | −234.9 | −237.1 | 0.2 | 146.8 | 483 |
| S4 | −194.4 | −200.3 | 0.1 | 210.0 | 438 |
Figure 6
SEM images of the cross-section of the corroded surface of coatings: (a) S1, (b) S2, (c) S3, and (d) S4.
Figure 7
Average values of the roughness parameter measured with the stylus profilometer.