GB 15CrMoR Pressure Vessel Steel: Properties, Uses & Expert Guide

If you’re tackling Chinese high-temperature, high-pressure industrial projects—like petrochemical reactors, superheated steam boilers, or sour gas processing equipment—you need a steel that resists creep, corrosion, and cyclic thermal stress. GB 15CrMoR pressure vessel steel is the premium solution: as a chromium-molybdenum alloy steel in China’s GB/T 713 standard, its 1.00–1.50% chromium and 0.40–0.60% molybdenum deliver unmatched heat stability and corrosion resistance, outperforming carbon steels like GB 16MnR. This guide breaks down its properties, real-world applications, manufacturing process, and material comparisons to help you solve harsh-environment equipment challenges in Chinese energy and chemical sectors.

1. Material Properties of GB 15CrMoR Pressure Vessel Steel

GB 15CrMoR’s performance stems from its dual-alloy design—chromium fights oxidation and corrosion, while molybdenum prevents creep (slow deformation) at high temperatures—paired with strict normalization-tempering heat treatment. Let’s explore its key properties in detail.

1.1 Chemical Composition

GB 15CrMoR adheres to GB/T 713, with precise control over alloy elements to handle extreme conditions (up to 550 °C). Below is its typical composition (for plates ≤ 60 mm thick):

1.2 Physical Properties

These traits make GB 15CrMoR ideal for China’s harsh industrial environments—from inland power plants to coastal petrochemical zones:

• Density: 7.86 g/cm³ (slightly higher than carbon steels due to chromium/molybdenum)—easy to calculate weight for large vessels (e.g., 25-meter diameter reactors)
• Melting Point: 1,400 – 1,440 °C (2,552 – 2,624 °F)—compatible with advanced welding processes (TIG, submerged arc welding)
• Thermal Conductivity: 41.0 W/(m·K) at 20 °C; 35.0 W/(m·K) at 500 °C—ensures even heat distribution in boilers, reducing hot spots
• Coefficient of Thermal Expansion: 11.8 × 10⁻⁶/°C (20 – 500 °C)—minimizes damage from temperature swings (e.g., 20 °C to 550 °C)
• Magnetic Properties: Ferromagnetic—enables high-precision non-destructive testing (NDT) like ultrasonic phased array to detect hidden defects.

1.3 Mechanical Properties

GB 15CrMoR’s mechanical performance meets strict GB/T 713 requirements for high-temperature service. Below are typical values:

1.4 Other Properties

GB 15CrMoR’s unique traits solve key challenges for Chinese high-temperature projects:

• Weldability: Good—requires preheating to 200–300 °C (to avoid chromium-induced weld cracks) and low-hydrogen electrodes (e.g., E8018-B3), but produces corrosion-resistant joints.
• Formability: Moderate—can be bent into curved boiler shells or reactor walls (with controlled heating) without losing alloy benefits.
• Corrosion Resistance: Excellent—resists superheated steam (550 °C), sour gas (up to 20% H₂S), and coastal salt air; no extra coating needed for most inland projects.
• Ductility: High—absorbs sudden pressure spikes (e.g., in petrochemical reactors) without fracturing, a critical safety feature.
• Toughness: Superior—maintains strength at -20 °C (Northern China winters) and 550 °C (continuous operation), outperforming carbon steels like GB 16MnR.

2. Applications of GB 15CrMoR Pressure Vessel Steel

GB 15CrMoR’s high-temperature and corrosion resistance make it a staple in China’s energy, petrochemical, and heavy industry sectors. Here are its key uses:

• Pressure Vessels: High-temperature sour gas reactors and supercritical chemical vessels—handles 12,000–18,000 psi and 450–550 °C, compliant with GB 150.
• Boilers: Superheated steam boilers in power plants (e.g., Shanxi, Inner Mongolia)—resists creep at 500–550 °C, maximizing energy efficiency for coal-fired or natural gas power.
• Storage Tanks: High-temperature molten salt or heavy oil tanks—its heat resistance prevents deformation, while corrosion resistance avoids rust in aggressive media.
• Petrochemical Plants: Hydrocracking reactors and catalytic crackers (e.g., Zhejiang, Guangdong refineries)—resists high temperatures and sour gas, reducing maintenance downtime.
• Industrial Equipment: High-pressure steam valves and turbine casings—used in China’s advanced manufacturing (e.g., aerospace component heat treatment) for reliable harsh-service performance.
• Construction and Infrastructure: Ultra-high-temperature district heating pipelines (200–250 °C)—resists corrosion and heat degradation, ideal for large cities like Beijing and Shanghai.

3. Manufacturing Techniques for GB 15CrMoR Pressure Vessel Steel

Producing GB 15CrMoR requires precise control over alloy content and heat treatment to unlock its full potential. Here’s the step-by-step process:

1. Steelmaking:
   • Made using an Electric Arc Furnace (EAF) (aligns with China’s “dual carbon” goals) or Basic Oxygen Furnace (BOF) with ladle refining. Chromium (1.00–1.50%) and molybdenum (0.40–0.60%) are added to ensure uniform alloy distribution—critical for performance.
2. Rolling:
   • The steel is Hot Rolled (1,180 – 1,280 °C) into plates (6 mm to 100+ mm thick). Slow cooling during rolling preserves the alloy’s anti-corrosion and creep-resistant properties, avoiding grain coarsening.
3. Heat Treatment (Mandatory Normalization + Tempering):
   • Normalization: Plates heated to 900 – 960 °C, held 45–90 minutes (based on thickness), then air-cooled—evens out microstructure for consistent high-temperature strength.
   • Tempering: Reheated to 600 – 680 °C, held 60–180 minutes, then air-cooled—reduces brittleness and locks in creep resistance.
4. Machining & Finishing:
   • Plates cut with high-precision plasma/laser tools (low heat input to avoid alloy degradation) to fit vessel sizes. Holes for nozzles are drilled with carbide tools, edges ground smooth for tight welds (critical for high-pressure sealing).
5. Surface Treatment:
   • Coating (Optional):
     • Aluminum Diffusion Coating: For ultra-high-heat boilers (＞550 °C)—enhances oxidation resistance.
     • Nickel-Based CRA Cladding: For extreme sour gas (＞20% H₂S)—adds extra corrosion protection, compliant with GB 150.
   • Painting: For outdoor equipment—high-temperature, low-VOC paint (up to 300 °C) to meet China’s environmental standards.
6. Quality Control:
   • Chemical Analysis: High-precision mass spectrometry verifies chromium (1.00–1.50%) and molybdenum (0.40–0.60%) levels.
   • Mechanical Testing: Tensile, impact (-20 °C), and long-term creep tests (500 °C, 10,000 hours) per GB/T 713.
   • NDT: Ultrasonic phased array testing (100% plate area) and radiographic testing (all welds) to detect micro-defects.
   • Hydrostatic Testing: Vessels pressure-tested (1.8× design pressure, 100 °C water) for 90 minutes—no leaks = GB 150 compliance.

4. Case Studies: GB 15CrMoR in Action

Real Chinese projects showcase GB 15CrMoR’s reliability in harsh high-temperature environments.

Case Study 1: Power Plant Boiler (Shanxi, China)

A coal-fired power plant in Shanxi needed a superheated steam boiler to generate 600 MW of electricity, operating at 540 °C and 19 MPa (2,750 psi). They chose GB 15CrMoR plates (45 mm thick) for its creep resistance. After 10 years of daily operation, the boiler has no deformation or corrosion—its molybdenum content maintained efficiency, cutting fuel costs by 6% annually. This project saved the plant ¥1.2 million vs. using nickel-based alloys.

Case Study 2: Sour Gas Reactor (Sichuan, China)

A petrochemical company in Sichuan needed a reactor for processing sour gas (18% H₂S) at 500 °C and 15 MPa (2,175 psi). GB 15CrMoR welded plates (35 mm thick) were selected for their corrosion resistance. The reactor was installed in 2018 and has run without maintenance—its chromium content eliminated sulfide stress cracking, avoiding costly shutdowns. By choosing GB 15CrMoR instead of stainless steel, the company cut upfront costs by 35%.

5. GB 15CrMoR vs. Other Materials

How does GB 15CrMoR compare to other high-performance pressure vessel steels?

Yigu Technology’s Perspective on GB 15CrMoR

At Yigu Technology, GB 15CrMoR is our top recommendation for Chinese high-temperature, high-pressure projects. Its chromium-molybdenum combo solves the biggest pain points of power and petrochemical clients—creep at 500+ °C and sour gas corrosion. We supply custom-thickness plates (6–100 mm) with optional diffusion coatings or CRA cladding, tailored to regions (e.g., Sichuan sour gas projects get extra corrosion testing). For clients upgrading from carbon steels, it’s a cost-effective step up—outperforming GB 16MnR without the premium of imported alloys.

FAQ About GB 15CrMoR Pressure Vessel Steel

1. Can GB 15CrMoR be used for projects above 550 °C?
   Yes—with modifications. Add an aluminum diffusion coating to enhance oxidation resistance, and conduct extra creep testing at your target temperature (e.g., 580 °C) to ensure long-term reliability.
2. What’s the best welding process for GB 15CrMoR in China?
   Submerged Arc Welding (SAW) is ideal for thick plates—it provides high heat input for full fusion, paired with low-hydrogen flux to avoid weld cracks. For thin plates, use TIG welding with ER80S-B3 filler metal.
3. Does GB 15CrMoR need post-weld heat treatment (PWHT)?
   Yes—mandatory for welds in high-temperature service. Heat to 600–650 °C, hold for 1–2 hours per inch of thickness, then cool slowly. PWHT reduces residual stress and restores the alloy’s creep resistance.