Welding 10CrMo9-10: preheat, filler and post-weld heat treatment
10CrMo9-10 (1.7380) is a 2.25 % Cr, 1 % Mo creep-resisting steel for boilers and pressure piping, to EN 10216-2 for seamless tube and EN 10028-2 for plate. The ASTM counterpart in the equivalents table is A335 P22. It is welded with preheat, a matching CrMo2 filler and, as a rule, heat treatment afterwards.
Short answer
ISO/TR 15608 group 5.2. thyssenkrupp says preheat to 200 °C above 10 mm wall; Böhler gives 200–350 °C preheat and interpass for its E CrMo2 B electrode and post-weld annealing at 700–750 °C for at least 1 hour, furnace cooling to 300 °C. For boiler work under pressure equipment rules, the heat treatment is set by the code and the WPS.
Grade card
| Designation and standard | 10CrMo9-10 · EN 10216-2 / EN 10028-2 |
|---|---|
| Material number | 1.7380 |
| GOST | 10Х2М |
| AISI / ASTM | A335 P22 |
| PN | — |
| ISO/TR 15608 group | 5.2 — vanadium-free Cr-Mo steel with 1.5 < Cr ≤ 3.5 % and 0.7 < Mo ≤ 1.2 % |
| Weldability (equivalents table) | preheat and heat treatment |
The EN, GOST, AISI/ASTM and PN rows come from the steel grade equivalents table. An equivalent is the closest grade, not an identical one.
The name reads: 10 — carbon in hundredths of a per cent, Cr and Mo — the alloying elements, 9-10 — their content multiplied by 4 and by 10, i.e. about 2.25 % Cr and 1 % Mo. thyssenkrupp states use in continuous service up to about 590 °C wall temperature.
10CrMo9-10 chemical composition, % by mass
| Element | TS (EN 10216-2) | P (EN 10028-2) |
|---|---|---|
| C | 0.08–0.14 | 0.08–0.14 |
| Si | ≤ 0.50 | ≤ 0.50 |
| Mn | 0.30–0.70 | 0.40–0.80 |
| P | ≤ 0.025 | ≤ 0.020 |
| S | ≤ 0.020 | ≤ 0.010 |
| Al | ≤ 0.040 | — |
| Cu | ≤ 0.30 | ≤ 0.30 |
| Cr | 2.00–2.50 | 2.00–2.50 |
| Mo | 0.90–1.10 | 0.90–1.10 |
Source: thyssenkrupp Materials Services, Werkstoffdatenblatt 10CrMo9-10, 01.2017.
TS — seamless tube (EN 10216-2), P — hot-rolled plate (EN 10028-2).
Mechanical properties
| Property | TS +NT |
|---|---|
| ReH, MPa, ≤ 16 mm | ≥ 280 |
| ReH, MPa, 16–40 mm | ≥ 280 |
| ReH, MPa, 40–60 mm | ≥ 270 |
| Rm, MPa | 480–630 |
| A, % | ≥ 22* |
Source: thyssenkrupp Materials Services, Werkstoffdatenblatt 10CrMo9-10, 01.2017.
* Longitudinal test pieces; the datasheet gives 20 % for transverse ones.
These are tube values (TS, +NT, normalised and tempered); plate (P) to EN 10028-2 has its own figures by thickness on the same datasheet.
Carbon equivalent: CE, CET and the CEV limit
| Value | Formula | Result | Basis |
|---|---|---|---|
| CE (IIW) | C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 | 1.00 | upper composition limits from the table |
| CET | C + (Mn+Mo)/10 + (Cr+Cu)/20 + Ni/40 | 0.46 | upper composition limits from the table |
From the upper composition limits, CE falls in the calculator band: Poor — Preheat 200–350 °C, keep it warm while welding, stress relief afterwards.
CE (IIW) from the upper limits is about 1.00, far above the 0.60 edge of our CE bands, and CET is 0.46. The preheat formula of our calculator is set up for structural steels (its grade list ends at 30ХГСА), so for 10CrMo9-10 the preheat comes from the steel and filler datasheets below, not from the formula.
Enter the analysis from your mill certificate in the carbon equivalent calculator: the link opens it with the composition limits from this page, ready to overwrite.
Preheat and interpass temperature
| Step | Temperature | Source |
|---|---|---|
| Preheat, wall over 10 mm | 200 °C | thyssenkrupp |
| Preheat and interpass, depending on wall thickness | 200–350 °C | Böhler FOX CM 2 Kb |
| Post-weld annealing, at least 1 h, furnace cooling to 300 °C, then still air | 700–750 °C | Böhler FOX CM 2 Kb |
| Heat treatment at which the weld metal properties are stated, 1 h | 690–750 °C | Gedik OPUS 2 CM-15 |
| Tempering range of the steel | 650–750 °C | thyssenkrupp |
| Electrode redrying, at least 2 h | 300–350 °C | Böhler FOX CM 2 Kb, Gedik OPUS 2 CM-15 |
thyssenkrupp: for work under boiler rules the post-weld heat treatment is specified separately, otherwise stress-relieve. Keep the joint at preheat temperature until the heat treatment starts, so it does not cool down hard and loaded with hydrogen.
Filler metal
| Process | Filler | Gas |
|---|---|---|
| 111 — stick (MMA) | E CrMo2 B 4 2 H5 / E9018-B3 H4R — Böhler FOX CM 2 Kb; E CrMo2 B 42 H5 / E9015-B3 H4 — Gedik OPUS 2 CM-15; Phoenix SH Chrom 2KS | DC+ |
| 141 — TIG | Union I CrMo 910 | Ar |
| 135 — MAG, solid wire | Union I CrMo 910 | — |
| 136 — MAG, flux-cored wire | Union MV CrMo 9 10 | M21 |
| 121 — submerged arc | Union S1CrMo2 / UV 420 TTR | — |
The filler must match the alloy: E CrMo2 B (2.25Cr-1Mo). E CrMo1 B, which suits 13CrMo4-5, is a different class (1Cr-0.5Mo) and does not give the creep strength of P22. Basic electrodes are redried at 300–350 °C for at least 2 hours (Böhler, Gedik) and run on DC+.
How to weld it
- Preheat to the WPS range (datasheets: 200 °C above 10 mm; 200–350 °C), measured on both sides of the joint.
- Redried basic electrodes E CrMo2 B, DC+.
- Keep interpass within the preheat–interpass range of the filler datasheet.
- Do not let the joint cool to room temperature before post-weld heat treatment unless the WPS allows it.
- Post-weld heat treatment per the WPS and code; the Böhler datasheet gives 700–750 °C, at least 1 h, furnace cooling to 300 °C. Heat input: heat input calculator.
Substituting the equivalent: what changes in the paperwork
ASTM A335 P22 tube and 10CrMo9-10 are interchangeable in the sense that the same consumables (E CrMo2 B, AWS E9018-B3) are listed for both by Böhler; whether one replaces the other on a pressure system is decided by the design code and the inspector.
In the WPS, write 10CrMo9-10 and group 5.2. A procedure qualified on group 1 structural steel does not cover it.
Where the figures come from
- thyssenkrupp Materials Services, Werkstoffdatenblatt 10CrMo9-10 (1.7380), 01.2017
- voestalpine Böhler Welding, FOX CM 2 Kb, 03/2014
- Gedik Welding, OPUS 2 CM-15
- ISO/TR 15608:2013, tab. 1 (later ISO/TR 15608:2017; replaced by ISO 15608:2025)
Figures from distributor and manufacturer datasheets are for information; for a given delivery, the EN 10204 3.1 certificate decides. CE, CET and preheat are calculated when the page is shown, with the same formulas as the calculators.
Frequently asked questions
What preheat for 10CrMo9-10?
thyssenkrupp gives 200 °C for wall thicknesses above 10 mm; the Böhler FOX CM 2 Kb electrode datasheet gives 200–350 °C preheat and interpass depending on wall thickness. The WPS decides the exact range.
What post-weld heat treatment for 10CrMo9-10?
The Böhler FOX CM 2 Kb datasheet: post-weld annealing at 700–750 °C for at least 1 hour, furnace cooling to 300 °C, then still air. thyssenkrupp: under boiler rules the treatment is specified separately, otherwise the part is stress-relieved.
Which electrode for 10CrMo9-10?
A basic 2.25Cr-1Mo electrode: E CrMo2 B to EN ISO 3580-A, for example Böhler FOX CM 2 Kb (E9018-B3 H4R) or Gedik OPUS 2 CM-15 (E9015-B3 H4). Redry at 300–350 °C for at least 2 h, DC+.
What is the composition of 10CrMo9-10?
Seamless tube to EN 10216-2 (thyssenkrupp datasheet): C 0.08–0.14 %, Si up to 0.50 %, Mn 0.30–0.70 %, P up to 0.025 %, S up to 0.020 %, Cr 2.00–2.50 %, Mo 0.90–1.10 %, Cu up to 0.30 %.
Is 10CrMo9-10 the same as P22?
It is the closest ASTM counterpart: A335 P22 for pipe, with the same 2.25Cr-1Mo chemistry type, and Böhler lists one electrode for both. They are separate specifications with their own limits and tests.
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