Q460R

1. Brief Introduction

Q460R is the highest strength grade pressure vessel steel plate in the GB 713 standard, with a minimum yield strength of 460 MPa. This steel achieves high strength and toughness through micro-alloying and quenching and tempering treatment, offering excellent weldability and resistance to brittle fracture. It is primarily used in the manufacture of large high-pressure vessels, heavy-duty reactors, and other critical equipment bearing high loads.

2. Grade Designation Explanation

- Q: First letter of the Chinese Pinyin "Qū" for Yield Strength .
- 460: Minimum yield strength value (in MPa) for thickness ≤16 mm.
- R: First letter of the Chinese Pinyin "Róng" for Pressure Vessel.

3. Physical Properties

 Density: 7.85 g/cm³        
 Elastic Modulus: 205 GPa          
 Poisson's Ratio: 0.29              
 Thermal Expansion Coefficient: 11.8×10⁻⁶/°C  
 Thermal Conductivity: 43.5 W/(m·K)      
 Specific Heat Capacity: 0.46 kJ/(kg·K)    

4. Chemical Composition (Ladle Analysis, %)

 Element  Content        
C ≤0.18          
Si 0.15-0.50      
Mn 1.40-1.70      
P ≤ 0.020        
S ≤ 0.015        
Nb/V/Ti  Complex Micro-alloying
Alt ≥0.020        

Characteristics:
- Utilizes a low carbon equivalent design (Ceq ≤ 0.52), strictly controlling susceptibility to weld cold cracking.
- Nb-V-Ti complex micro-alloying achieves grain refinement strengthening and precipitation strengthening.
- Ultra-low phosphorus and sulfur content ensures excellent low-temperature toughness.
- Requires -20°C impact toughness testing.

5. Application Fields

- Heavy Petrochemical Equipment: Large hydrogenation reactors (wall thickness >150 mm), coal liquefaction reactors.
- Nuclear Power Equipment: Nuclear island main equipment, containment components.
- Energy Sector: Ultra-large capacity hydraulic turbine spiral casings, high-pressure power station boilers.
- Special Equipment: High-pressure vessels for aerospace, pressure hulls for deep-sea equipment.

6. Testing and Production Methods

Production Process:
- Electric furnace smelting → LF refining → VD vacuum degassing → RH circulation treatment.
- Thermo-Mechanical Controlled Processing (TMCP) + online quenching + tempering (Q+T).
- Precise temperature control throughout the process to maximize grain refinement.

Performance Requirements:
- Tensile properties: Rp0.2 ≥ 460 MPa, Rm ≥ 570-740 MPa.
- Impact toughness: KV2 ≥ 47J at -20°C (tested at -30°C for thickness >50 mm).
- Bend test: 180° bending (d=3a) without cracking.
- Ultrasonic testing: Meets JB/T 4730.3 Level I requirements.

7. Internationally Equivalent Grades