10CrMo910 vs 12Cr1MoV – Composition, Heat Treatment, Properties, and Applications
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Table Of Content
Table Of Content
Introduction
10CrMo910 and 12Cr1MoV are two chromium–molybdenum alloy steels frequently considered for elevated-temperature pressure parts such as boiler tubes, piping, and turbine components. Engineers and procurement professionals commonly weigh tradeoffs between high-temperature strength and long-term creep resistance versus oxidation resistance, weldability, and cost. Typical decision contexts include choosing materials for steam service at different temperature/pressure bands, selecting tubing for power plants, or specifying forgings and pipes where fabrication ease and post-weld performance matter.
The primary practical difference between these grades is their alloying strategy: one emphasizes a balance of chromium with microalloying elements to maximize high-temperature strength and creep resistance, while the other contains a higher chromium proportion targeted at improved oxidation and scaling resistance with a different tempering and service envelope. Because they occupy overlapping but not identical service windows, they are often compared when optimizing for temperature capability, weldability, and lifecycle cost.
1. Standards and Designations
- 10CrMo910
- Commonly associated with high-chromium, martensitic/ferritic steels used for power plant piping and tubes. It is offered under national standards in Europe and China and is often used as an alternative designation to steels in the P9x family (consult specific national standard for exact equivalence).
- Typical standard types: EN and GB variants; consult the applicable standard (e.g., EN or GB/China) and manufacturer data for exact designation and limits.
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Classification: Alloy steel (heat-resistant / creep-strengthened steel).
-
12Cr1MoV
- A higher-chromium, vanadium- and molybdenum-containing alloy used historically in fossil power and petrochemical equipment.
- Appears in Eastern European and Russian standards (GOST) and some national catalogs; also referenced in international literature for steam applications.
- Classification: Alloy steel (high-chromium heat-resistant steel).
Note: Neither grade is a stainless steel by modern definitions (i.e., >11–12% Cr and specific corrosion-resisting metallurgy), although 12Cr1MoV can approach chromium levels where oxidation resistance improves. Always check the exact standard designation and certified chemical limits for procurement.
2. Chemical Composition and Alloying Strategy
Typical nominal composition ranges (wt%) commonly reported for these families are shown below. These are representative ranges—always confirm with the supplier’s certificate or the specific standard.
| Element | 10CrMo910 (typical nominal range, wt%) | 12Cr1MoV (typical nominal range, wt%) |
|---|---|---|
| C | 0.05 – 0.12 | 0.08 – 0.18 |
| Mn | 0.20 – 0.60 | 0.30 – 0.70 |
| Si | 0.10 – 0.60 | 0.10 – 0.50 |
| P (max) | ≤ 0.025 | ≤ 0.030 |
| S (max) | ≤ 0.010 | ≤ 0.020 |
| Cr | 8.5 – 10.5 | 11.0 – 13.0 |
| Ni | ≤ 0.40 | ≤ 0.40 |
| Mo | 0.80 – 1.05 | 0.30 – 0.70 |
| V | 0.05 – 0.30 | 0.08 – 0.30 |
| Nb (or Ta) | 0.03 – 0.12 (where specified) | – |
| Ti | ≤ 0.02 (where specified) | – |
| B | ≤ 0.003 (possible small additions) | – |
| N | ≤ 0.03 | ≤ 0.03 |
Interpretation of alloying effects - Chromium (Cr): raises oxidation and scaling resistance at high temperature, increases hardenability and tempering resistance. 12Cr1MoV’s higher Cr gives better surface oxidation resistance and scale adherence at some temperatures. - Molybdenum (Mo): strengthens the matrix at elevated temperature and improves creep resistance. 10CrMo910 commonly has higher Mo to boost high-temperature strength. - Vanadium (V): forms fine carbides/nitrides that pin dislocations and grain boundaries, improving creep strength and temper softening after long-term exposure. - Niobium (Nb), titanium (Ti), boron (B): microalloying additions refine grain size, stabilize carbides/nitrides, and can enhance creep and toughness. - Carbon (C): contributes to strength and hardenability; higher C increases strength but reduces weldability and toughness if not controlled.
3. Microstructure and Heat Treatment Response
Typical microstructures: - 10CrMo910: Designed to develop a tempered martensitic microstructure after normalization and tempering. The microstructure consists of tempered lath martensite with dispersed carbides and carbonitrides (V, Nb, Mo-containing precipitates) that confer high creep strength. - 12Cr1MoV: Also normally normalized and tempered to produce tempered martensite, but the higher Cr may encourage formation of different M23C6-type carbides and more stable scale-forming oxides. Microalloying gives precipitation strengthening similar to 10CrMo910 but the carbide chemistry shifts.
Heat treatment response: - Normalizing: Both grades benefit from controlled normalization to dissolve coarse carbides and produce a uniform austenitic grain that transforms to martensite on cooling. - Quenching & tempering: Typical route is normalization followed by tempering at temperatures tailored to achieve desired strength–toughness balance. Tempering reduces hardness, stabilizes carbides, and restores ductility. - Thermo-mechanical processing: Thermo-mechanical controlled processing (TMCP) can refine grains and precipitate fine dispersoids—especially valuable for tubing and plate to improve toughness and creep performance. - Aging and long-term exposure: Both steels show tempered martensitic softening and coarsening of precipitates with time at temperature. Higher Mo and controlled microalloying slow degradation in 10CrMo910-like steels.
4. Mechanical Properties
The table below gives a qualitative comparative snapshot rather than absolute values (because property levels depend on heat treatment and exact sub-grade). Consult mill certificates and relevant design codes for numeric design values.
| Property | 10CrMo910 | 12Cr1MoV | Commentary |
|---|---|---|---|
| Tensile strength | Higher (typically) | Moderate | 10CrMo910-style alloys are optimized for higher tensile strength at elevated temperature due to Mo and microalloying. |
| Yield strength | Higher (typically) | Moderate | Microalloying and Cr–Mo chemistry raise yield and high-temp creep strength in 10CrMo910. |
| Elongation (ductility) | Good (depends on temper) | Good | Both can achieve acceptable ductility after proper tempering; higher C reduces ductility. |
| Impact toughness (room-temp) | Good to very good with proper heat treatment | Good | Toughness depends on cleanliness and heat treatment; both can be tough if controlled. |
| Hardness (as-tempered) | Higher (for strength targets) | Moderate | 10CrMo910 tends to be tempered to hardness levels supporting higher design stress. |
Which is stronger, tougher, or more ductile and why - Strength: 10CrMo910-type steels are typically specified for higher design stress and creep resistance because of higher Mo plus microalloying (V, Nb) that help precipitation strengthening. - Toughness: With proper normalization and tempering, both grades can provide satisfactory toughness. Cleaner steelmaking and tight control of C and N help maintain impact properties. - Ductility: Both achieve acceptable ductility, but higher carbon and heavy precipitation can reduce elongation if not carefully processed.
5. Weldability
Weldability is influenced by carbon equivalent, alloying elements, and the presence of microalloying elements that increase hardenability.
Useful predictive formulas: - IIW carbon equivalent: $$CE_{IIW} = C + \frac{Mn}{6} + \frac{Cr+Mo+V}{5} + \frac{Ni+Cu}{15}$$ - Pcm (WRC) for hydrogen-induced cold cracking prediction: $$P_{cm} = C + \frac{Si}{30} + \frac{Mn+Cu}{20} + \frac{Cr+Mo+V}{10} + \frac{Ni}{40} + \frac{Nb}{50} + \frac{Ti}{30} + \frac{B}{1000}$$
Qualitative interpretation: - 10CrMo910: Higher Mo and microalloying raise hardenability and CE/Pcm, increasing risk of hard martensitic HAZ, cold cracking, and the need for preheat and post-weld heat treatment (PWHT). PWHT is mandatory for pressure applications to temper the HAZ and relieve residual stresses. - 12Cr1MoV: The higher Cr content also increases hardenability, but lower Mo may reduce some hardenability compared to 10CrMo910; nevertheless, preheat and PWHT are often required. Both grades require qualified welding procedures, controlled interpass temperatures, and sometimes matching filler metals to avoid soft zones or brittle phases. - Practical guidance: Use low-hydrogen welding consumables, adequate preheat, controlled heat input, and PWHT to the specified temperature. Always follow code (ASME, EN, or national) requirements for PWHT and post-weld testing.
6. Corrosion and Surface Protection
- Neither grade is a stainless steel in the sense of being corrosion-resistant in wet environments. Protection strategies are required for atmospheric, aqueous, or corrosive environments.
- Surface protection: galvanizing is generally not used for high-temperature steam service; instead, protective coatings (high-temperature paints), alloy cladding, or internal linings are employed as needed. Cathodic protection and corrosion allowance are typical in design.
- Oxidation and scaling: Higher Cr in 12Cr1MoV improves formation of adherent chromium-rich oxide scales and can reduce oxidative mass loss at higher steam temperatures compared with lower-Cr steels. However, actual oxidation performance depends on temperature, steam chemistry, and service exposure time.
- PREN (not generally applicable): For stainless alloys a PREN index is used: $$\text{PREN} = \text{Cr} + 3.3 \times \text{Mo} + 16 \times \text{N}$$ This index is not applicable to these non-stabilized alloy steels for general corrosion selection—use it only for stainless alloys.
7. Fabrication, Machinability, and Formability
- Machinability: Higher strength and harder as-processed conditions decrease machinability. 12Cr1MoV with higher Cr may be slightly more abrasive; 10CrMo910 with microalloying precipitates may reduce tool life. Machining should be performed in normalized or annealed conditions where possible.
- Formability and bending: Both are limited in cold forming when in normalized-and-tempered condition; forming is easier when supplied in normalized condition (or in solution-treated softer condition if available). Heat treatment after forming is often required.
- Finishing: Grinding and surface finishing are similar to other alloy steels; use appropriate coolant and tooling to manage hardness and abrasivity.
8. Typical Applications
| 10CrMo910 | 12Cr1MoV |
|---|---|
| High-temperature steam piping, reheater/superheater tubes, components requiring elevated creep strength up to mid-high steam temperatures | Steam headers, high-temperature piping where enhanced oxidation resistance and scale control are important |
| Power plant components where design seeks higher allowable stress or extended creep life | Components where surface oxidation resistance is prioritized alongside moderate creep resistance |
| Pressure parts requiring stringent PWHT routines and high-strength weldable solutions | Pressure components in thermal power and petrochemical plants with service in oxidizing atmospheres |
Selection rationale: - Choose 10CrMo910-like alloys where high-temperature strength, creep resistance, and long-term mechanical stability under stress are prime design drivers. - Choose 12Cr1MoV where oxidation/scale resistance and surface stability at elevated temperatures are relatively more important and where slightly different fabrication tradeoffs are acceptable.
9. Cost and Availability
- Cost: Material cost depends on alloy content and production route. Alloys with higher Mo and microalloying additions (10CrMo910 family) are typically more expensive per kilogram than simpler Cr–Mo steels because of alloying and stricter processing controls.
- Availability: Both grades are available in tube, piping, plate, and forging forms from specialty mills. Availability may vary by region; P91-style steels (10CrMo910 family) are widely available in markets with large thermal power industries, while region-specific grades like 12Cr1MoV may be more common in Eastern European and some Asian supply chains.
- Lead time: For high-specification grades and qualified materials, lead times increase—plan procurement early and require mill test certificates and heat-treatment records.
10. Summary and Recommendation
Summary table (qualitative)
| Attribute | 10CrMo910 | 12Cr1MoV |
|---|---|---|
| Weldability | Fair (requires preheat/PWHT; higher hardenability) | Fair (requires preheat/PWHT) |
| Strength–Toughness (elevated T) | High strength and creep resistance | Moderate–high, good toughness |
| Cost | Higher (due to Mo and microalloying) | Moderate |
Concluding recommendations - Choose 10CrMo910 if: - The design requires higher allowable stresses at elevated temperature or superior creep resistance. - Long-term mechanical stability under sustained high temperature and stress is a priority. - You can accommodate more stringent welding controls (preheat, PWHT) and slightly higher material cost.
- Choose 12Cr1MoV if:
- Surface oxidation/scale resistance and a higher chromium content are important for your operating environment.
- You seek a balance of good elevated-temperature performance with moderate cost and supply availability in certain regions.
- Fabrication and procurement constraints favor a simpler Cr–Mo alloy chemistry.
Final note: These grades are defined by specific standards whose exact limits and mechanical design values vary. Always use the precise material standard and the mill test certificate to verify chemical composition, heat treatment condition, and certified mechanical properties before design acceptance or procurement.