Heat-resistant Cr-Mo steels
FERVEO CMO MoB
covered electrode · stick electrodeCatalogue only
AWS class
E 7018-A1 H4
EN ISO class
E Mo B 42 H5
Tensile strength (Rm)
530–670 MPa
Classification
| AWS class | E 7018-A1 H4 |
|---|---|
| EN ISO class | E Mo B 42 H5 |
Purpose
- Basic-coated molybdenum electrode (0.5% Mo, EN ISO E Mo B 42 H5, AWS E7018-A1), with certified cold toughness — for welding low-alloy heat-resistant Mo steels in more demanding joints.
Why it works
The same molybdenum as FERVEO CMO MoR gives creep resistance under sustained elevated-temperature service; the basic coating adds better diffusible-hydrogen control than rutile — hence a much more demanding certified toughness (tested well below room temperature, versus room temperature only for FERVEO CMO MoR), at the cost of somewhat more careful electrode handling.
Fields of application
- Low-alloy molybdenum steel boilers and piping in continuous elevated-temperature service, where certified cold toughness or higher joint restraint is required.
Chemical composition
| Element | Typical, % |
|---|---|
| C | 0.07 |
| Mn | 0.9 |
| Mo | 0.5 |
| Si | 0.4 |
Mechanical properties
| Tensile strength (Rm) | 530–670 MPa |
|---|---|
| Yield strength (Rp0.2) | 460 MPa |
| Elongation (A5) | 22 % |
| Impact energy (KV) | 47 J (−50 °C) |
Process
| Polarity | DC+ |
|---|---|
| Positions | PAflatPBhorizontal-verticalPChorizontalPDhorizontal-overheadPEoverheadPFvertical-up |
| Re-drying | 300-350°C min. 2h |
| Heat treatment | 620°C / 1h / |
Sizes and part numbers
| Ø | Length | Current | Request |
|---|---|---|---|
| 2.5 mm | 350 mm | 80–110 A | |
| 3.2 mm | 350 mm | 100–140 A | |
| 4 mm | 450 mm | 140–190 A | |
| 5 mm | 450 mm | 190–240 A |
Cross-reference
| Replaces FOX DMO Kb (Böhler) | Direct replacement |
| Replaces EM 202 (Magmaweld) | Direct replacement |
| Replaces AS DA-735 (Askaynak) | Direct replacement |
| Replaces MOLYCORD KV2HR (Oerlikon) | Direct replacement |
Equivalence refers to the classification (AWS / EN ISO), not to product identity. In applications with a qualified procedure (WPS), validate the substitution before use.
Base metals
S355J2G3E295E335P255G1TH16Mo3L320-L415NBL290MB-L415MBS255N-S460NP295GH P355GH15NiCuMoNb5S20MnMoNi4-517MnMoV6-4S255NH-S460NHS255NL-S460NLGE240-GE300GS22Mo4
Advantages
- Certified toughness well below room temperature — a better choice than FERVEO CMO MoR for higher-restraint or higher-responsibility joints.
- Low diffusible hydrogen (H5) — lower cold-cracking risk than a rutile electrode in stiffer joints.
Limitations
- No chromium in the alloy — like FERVEO CMO MoR, the lowest creep- and hot-oxidation-resistance step in the family; for more demanding duty, see the chromium-bearing grades.
- Basic coating demands more careful handling than rutile — less forgiving striking and re-striking than FERVEO CMO MoR.