Seamless steel pipe,Precision Seamless Steel Tube Manufacturer

Material Science Guide – 12Cr1MoVG

1. Grade Interpretation

12: Denotes the carbon content of this steel grade, with a mass fraction of carbon approximately 0.08%‑0.15%. Relatively low carbon content ensures favorable weldability and toughness for steel tubes, preventing defects such as cracks during welding.
Cr1: Indicates chromium mass fraction of approximately 0.9%‑1.2%. Chromium improves oxidation resistance, corrosion resistance and high‑temperature strength of steel tubes. It promotes formation of a stable oxide film at high temperatures to slow down oxidative corrosion.
MoV: Refer to molybdenum (mass fraction: 0.25%‑0.35%) and vanadium (mass fraction: 0.15%‑0.30%) respectively. Molybdenum enhances high‑temperature creep resistance and resists deformation under long‑term high‑temperature loading. Vanadium refines grain structure, further boosting strength and toughness and optimizing mechanical properties.
G: Initial letter of Chinese Pinyin for “steel for boilers”. It signifies this grade is engineered for high‑temperature pressure‑bearing equipment such as boilers, complying with specific standards and requirements for boiler‑grade steel.

Carbon (C): 0.08%‑0.15%
Silicon (Si): 0.17%‑0.37%. Improves oxidation & corrosion resistance and increases steel strength.
Manganese (Mn): 0.40%‑0.70%. Enhances forgeability, toughness and tensile strength.
Chromium (Cr): 0.90%‑1.20%. One of the key alloying elements; improves oxidation resistance, corrosion resistance and high‑temperature strength.
Molybdenum (Mo): 0.25%‑0.35%. Reinforces high‑temperature creep resistance and stability under prolonged high‑temperature stress.
Vanadium (V): 0.15%‑0.30%. Refines grains, elevates strength and toughness, optimizes mechanical performance.
Phosphorus (P): ≤0.030%. Harmful impurity to be strictly controlled. Excess phosphorus reduces toughness and increases cold‑brittleness tendency.
Sulfur (S): ≤0.020%. Harmful impurity. Excess sulfur causes hot‑brittleness and impairs weldability and mechanical properties; strict limitation is required.

Primarily used for boiler equipment in thermal power plants, including superheater tubes and reheater tubes. These components operate continuously under high‑temperature and high‑pressure conditions to carry high‑temperature steam, and 12Cr1MoVG steel tubes satisfy their performance demands.
Suitable for high‑pressure steam pipelines. Deployed in power plants and large‑scale chemical plants to transport high‑parameter media (e.g. high‑temperature high‑pressure steam), ensuring safe and stable steam conveyance.
Applicable to high‑temperature pressure‑bearing pipe fittings for large chemical equipment, such as connecting pipes for reaction kettles and heat‑exchange tubes for heat exchangers, serving high‑temperature reaction conditions in chemical production.
Partially adopted for auxiliary piping systems in nuclear power plants, for non‑critical pipelines subject to moderate high‑temperature and high‑pressure service conditions.

Excellent high‑temperature mechanical properties: Within long‑term service temperature up to 580℃, it delivers outstanding strength, toughness and creep resistance. Capable of sustaining long‑term loads under high temperature and pressure with low risk of deformation or rupture.
Good weldability: Low carbon content together with well‑balanced alloy composition minimizes welding cracks. Mechanical properties of welded joints are close to base metal, facilitating on‑site installation and joint assembly.
Superior oxidation‑corrosion resistance: Chromium forms a dense protective oxide film at high temperatures, blocking corrosive media such as oxygen from internal attack and extending service life.
Good process adaptability: Supports multiple processing methods including cold and hot working (bending, rolling, etc.). Can be fabricated into pipe fittings of varied shapes and specifications per engineering requirements to satisfy diverse installation scenarios.

Limited resistance to extreme corrosion: Compared with stainless steel (e.g. 316L) and nickel‑base alloys, it shows poor resistance to acid‑alkali and chloride‑ion corrosion. It is prone to corrosive damage and unsuitable for long‑term service in heavily corrosive chemical environments such as concentrated sulfuric acid, hydrochloric acid or high‑salinity conditions.
Restricted maximum service temperature: Maximum long‑term operating temperature is around 580℃. Beyond this threshold, creep resistance and strength drop sharply. It cannot meet ultra‑high‑temperature service (>600℃), and higher‑temperature grades such as A335 P91 shall be used instead.
Higher cost than ordinary carbon steel: Alloy additions of chromium, molybdenum and vanadium raise manufacturing cost. It is less cost‑effective for general pipelines with low performance requirements.
Insufficient low‑temperature toughness: Toughness deteriorates markedly below ‑20℃ with risk of brittle fracture. Not recommended for low‑temperature storage tanks or cryogenic transfer pipelines.

Temperature: Optimized for moderate‑to‑high temperature of 300℃‑580℃. Ideal for thermal‑power boiler superheaters, reheaters and other components operating within this range. Avoid service below 0℃ or above 580℃.
Pressure: Suited for high‑pressure service at rated pressure 10MPa‑30MPa, e.g. high‑pressure steam pipelines and boiler pressure‑bearing fittings. Maintains structural integrity without leakage or deformation under high pressure.
Media: Suitable for clean neutral media such as high‑temperature steam and hot water. Avoid media with high‑concentration acid‑alkali, chloride ions or sulfides. Extra anti‑corrosion treatment (e.g. coating protection) is required for mildly corrosive environments.
Industry scope: Main application is thermal‑power generation as core tubing for conventional thermal power boilers. In chemical industry, only for non‑corrosive high‑temperature steam lines and ordinary heating equipment piping. In energy sector, applicable to high‑pressure steam piping of medium‑and‑small power stations. Not suitable for ultra‑critical / super‑ultra‑critical power station core piping under extreme high‑temperature‑pressure (higher‑grade materials are required).