Q370R

1. Brief Introduction

Q370R is a high-strength low-alloy steel plate for pressure vessels, classified under the GB 713 standard "Steel Plates for Boilers and Pressure Vessels." It has a yield strength of no less than 370 MPa, offering excellent comprehensive mechanical properties, weldability, and resistance to embrittlement. Its fine-grained structure is achieved primarily through micro-alloying and normalizing treatment. It is widely used in manufacturing medium-to-high-pressure pressure vessels, reactors, storage tanks, and other equipment.

2. Grade Designation Explanation

    Q: Represents the first letter of the Chinese Pinyin "Qū" for yield strength.
    370: Indicates the minimum yield strength value (in MPa) for thickness ≤16 mm.
    R: Represents the first letter of the Chinese Pinyin "Róng" for pressure vessels.

3. Physical Properties

    Density: 7.85 g/cm³
    Elastic Modulus: 210 GPa
    Poisson's Ratio: 0.3
    Thermal Expansion Coefficient: 12.5×10⁻⁶/°C (20-100°C)
    Thermal Conductivity: 47.0 W/(m·K)
    Specific Heat Capacity: 0.48 kJ/(kg·K)

4. Chemical Composition (Ladle Analysis, %)

C    ≤0.18
Si    0.15-0.55
Mn    1.20-1.60
P    ≤0.020
S    ≤0.015
Alt    ≥0.020

Features: Utilizes a low-carbon design with a carbon equivalent (Ceq) ≤0.45, ensuring good weldability. Strength is enhanced through Mn-Nb micro-alloying, while strict control of P and S content guarantees low-temperature toughness.

5. Application Fields

    Petrochemical Industry: Hydrogenation reactors, synthesis towers, high-pressure separators.
    Gas Storage and Transportation: Spherical liquefied gas tanks, high-pressure gas storage tanks.
    Energy Equipment: Power plant boiler drums, nuclear power plant pressure vessels.
    Heavy Machinery: Large pressure vessels, hydraulic press cylinders.

6. Testing and Production Methods

Production Process:
    Basic oxygen furnace (BOF) smelting + LF refining + VD vacuum degassing.
    Controlled rolling + normalizing heat treatment (N condition).
    Strict control of rolling temperature and pass reduction.

Testing Requirements:
    Tensile Test: Yield strength ≥370 MPa (t ≤16 mm).
    Impact Test: Lateral impact energy ≥47 J at 0°C.
    Bend Test: 180° bending (d=3a).
    Ultrasonic Testing: Complies with JB/T 4730.3 Level I requirements.

7. Internationally Equivalent Grades

    American Standard (ASTM/ASME): SA-516 Gr.70 (closest equivalent).
    European Standard (EN): P460NH (EN 10028-3).
    Japanese Standard (JIS): SPV450 (JIS G 3115).
    International Standard (ISO): P460NH (ISO 9328-2).

Note: While these grades are similar in strength level, differences may exist in specific chemical composition, impact energy requirements, and heat treatment systems. Confirmations should be made based on the specific standard requirements during use.