OK 74.78
OK 74.78 is an LMA electrode suitable for welding high tensile steels used in low-temperature applications. Good notch toughness down to -40°C. Very suitable for both the enclosed welding and cladding of rails, when a hardness of about 250 HV is required. The moisture content of the coating is very low, which makes OK 74.78 suitable when preheating cannot be applied.
Typical Tensile Properties
| ISO As welded | ||||
| Elongation | Tensile Strength | Yield Strength | Stress Relieved Temperature | Stress Relieved Testing Time |
| 24 % | 650 MPa | 600 MPa | – | – |
| AWS Stress relieved | ||||
| Elongation | Tensile Strength | Yield Strength | Stress Relieved Temperature | Stress Relieved Testing Time |
| – | – | – | 620 °C | 1 hr |
Typical Charpy V-Notch Properties
| ISO As welded | |||
| Impact Value | Testing Temperature | Stress Relieved Testing Temp | Stress Relieved Testing Time |
| 90 J | -40 °C | – | – |
| 70 J | -50 °C | – | – |
| AWS Stress relieved | |||
| Impact Value | Testing Temperature | Stress Relieved Testing Temp | Stress Relieved Testing Time |
| – | -50 °C | 620 °C | 1 hr |
Typical Weld Metal Analysis %
| Mn | Mo | C | Si | Ni | Cr |
| 1.60 % | 0.35 % | 0.05 % | 0.35 % | 0.03 % | 0.03 % |
Deposition Data
| Diameter | Current | Deposition Rate | Fusion time per electrode at 90% I max | kg weld metal/kg electrodes | Number of electrodes/kg weld metal | Voltage |
| 6.0 x 450 mm | 240-340 A | 3.6 kg/h | 103 sec | 0.69 kg | 10 | 24 V |
| 2.5 x 350 mm | 75-100 A | 0.90 kg/h | 55 sec | 0.62 kg | 73.0 | 22 V |
| 3.2 x 450 mm | 105-140 A | 1.30 kg/h | 86 sec | 0.65 kg | 32.0 | 23 V |
| 5.0 x 450 mm | 190-260 A | 2.60 kg/h | 100 sec | 0.68 kg | 14.0 | 24 V |
| 4.0 x 450 mm | 140-190 A | 1.80 kg/h | 97 sec | 0.65 kg | 20.5 | 23 V |
| Approvals: | ABS, 3Y H5, CE, EN 13479, DB, 82.039.02, DNV-GL, 3 Y46H5, VdTÜV, 01027 |
| Classifications: | SFA/AWS A5.5, E9018-D1, EN ISO 18275-A, E 55 4 MnMo B 3 2 H5 |
Approvals are based on factory location. Please contact ESAB for more information.
| Alloy Type: | Low alloyed (0.4 % Mo) |
| Coating Type: | IMPERIAL_Basic covering |
| Diffusible Hydrogen: | < 5.0 ml/100g |
| Welding Current: | AC, DC+ |