18MnMoNbR Steel Plate for Pressure Vessels (GB/T 713)
18MnMoNbR is a pressure vessel steel plate grade under the Chinese national standard. The manufacturing specification is GB/T 713.2-2023 (previous version: GB/T 713-2014), and the ultrasonic testing standard is NB/T 47013.3-2015.
This grade is a low-alloy steel containing manganese, molybdenum, and niobium, offering excellent strength and toughness for heavy-wall pressure vessels and high-temperature service.
18MnMoNbR steel plates are impact tested at 0 C as standard, with minimum absorbed energy of 47 J (average) for thickness 30-60mm and 41 J for thickness >60-100mm[citation:2][citation:5].
18MnMoNbR designation explanation: 18 stands for average carbon content (0.18%), Mn denotes Manganese, Mo denotes Molybdenum, Nb denotes Niobium, R denotes Pressure Vessel Steel[citation:1][citation:2][citation:3].
Product Overview
18MnMoNbR Steel Plate is a low-alloy pressure vessel steel manufactured in accordance with GB/T 713.2-2023. It contains manganese, molybdenum, and niobium as alloying elements, providing excellent strength, toughness, and weldability for heavy-wall pressure vessels and high-temperature applications[citation:1][citation:2].
Compared with Q345R, 18MnMoNbR offers higher strength (570-720 MPa tensile) and better high-temperature performance due to the addition of molybdenum and niobium, making it suitable for more demanding service conditions[citation:3][citation:5].
Core Advantages
- High strength with Mo and Nb microalloying
- Excellent high-temperature mechanical properties
- Customizable: HIC/SSC, high-temp properties
- Normalized + tempered (N+T) delivery condition
Applications
Stock Resources
Normalized plates: 30-100mm (W:2000-2500, L:11000-12500)
Hot-rolled plates: 6-36mm (W:1800-2500, L:11000-12500)
Hot-rolled coils: 5-16mm (W:1500-2000)
Spot stock size range and supply conditions
Supply Condition: CR, AR, N, N+T
18MnMoNbR Chemical Composition (max %)
| C | Si | Mn | Cu | Ni | Cr | Mo | Nb | P | S |
|---|---|---|---|---|---|---|---|---|---|
| <=0.21 | 0.15-0.50 | 1.20-1.60 | <=0.30 | <=0.30 | <=0.30 | 0.45-0.65 | 0.025-0.050 | <=0.020 | <=0.010 |
18MnMoNbR - Alloying Elements and Roles
per GB/T 713.2-2023Influences strength and hardness.
Deoxidizer, increases strength.
Enhances strength and toughness.
Harmful element, reduces toughness.
Harmful element, causes hot shortness.
Improves high-temperature strength and corrosion resistance[citation:1][citation:2].
Refines grain structure, improves strength and toughness[citation:1][citation:2].
As residual elements, Cu, Ni, Cr each <=0.30%, Mo as alloying element up to 0.60%[citation:1][citation:2][citation:7].
18MnMoNbR Mechanical Properties and Impact Test
| Thickness (mm) | YS (MPa) | TS (MPa) | Elong (%) | Impact 0 C (J) |
|---|---|---|---|---|
| 30-60 | >=400 | 570-720 | 18 | >=47 |
| >60-100 | >=390 | 570-720 | 18 | >=47 |
18MnMoNbR High-Temperature Mechanical Properties (Rp0.2 or RcL, MPa)
| Thickness (mm) | 100℃ | 150℃ | 200℃ | 250℃ | 300℃ | 350℃ | 400℃ | 450℃ | 500℃ |
|---|---|---|---|---|---|---|---|---|---|
| 30-60 |
375 |
365 | 360 | 355 | 350 | 340 | 310 | 275 | - |
| >60-100 | 370 | 360 | 355 | 350 | 345 | 335 | 305 | 270 | - |
Note: High-temperature tensile properties available upon request. Values based on GB/T 713.2-2023 Table 3[citation:3][citation:7][citation:8].
18MnMoNbR vs Q345R
| Item | 18MnMoNbR | Q345R |
|---|---|---|
| Standard | GB/T 713.2 | GB/T 713.2 |
| Alloying Elements | Mn, Mo, Nb | Mn |
| Yield Strength | >=400 MPa | >=345 MPa |
| Tensile Strength | 570-720 MPa | 510-640 MPa |
| Impact mandatory | Yes (0 C, >=47J) | Yes (0 C, >=34J) |
Scenario-Based Recommendation - GB Grade Comparison
Q345R
Charpy: 0 C
Q370R
Charpy -20 C
Q420R
Charpy -20 C
18MnMoNbR
Charpy 0 C (47 J)
16MnDR
Charpy -40 C
Quality Control and Inspection
Customizable Specification Range for 18MnMoNbR
Delivery Condition
AR as rolled - CR controlled rolled - TMCP thermo-mechanical - N+T normalized + tempered - N normalized
Additional Requirements
- Simulated post-weld heat treatment (PWHT)
- Brinell hardness requirements
- HIC / SSC testing
- High-temperature tensile properties
Other customized technical conditions are also negotiable.
The above ranges represent our standard customizing capability.
Frequently Asked Questions
What is 18MnMoNbR steel plate used for?
18MnMoNbR steel plate is mainly used for heavy-wall reactors, heat exchangers, separators, spherical tanks, nuclear reactor pressure shells, and LPG/LNG storage tanks requiring high strength and high-temperature performance[citation:1][citation:2].
What is the impact test temperature for 18MnMoNbR?
18MnMoNbR steel plates are impact tested at 0 C as standard, with minimum average absorbed energy of 47 J for thickness 30-60mm and 41 J for thickness >60-100mm[citation:2][citation:5].
What is the difference between Q345R and 18MnMoNbR?
18MnMoNbR offers higher strength (400 MPa yield vs 345 MPa) and better high-temperature performance due to the addition of molybdenum (0.45-0.60%) and niobium (0.025-0.050%). It is specifically designed for heavy-wall and high-temperature applications[citation:1][citation:2].
What is the delivery condition for 18MnMoNbR?
18MnMoNbR is typically delivered in normalized + tempered (N+T) condition with a tempering temperature not lower than 620 C[citation:6][citation:7][citation:11].
Can you provide 18MnMoNbR steel plates with custom sizes?
Yes. Custom rolling up to 100mm thick, 5200mm wide, 18000mm long. Delivery: 15-20 days hot-rolled, 30-35 days normalized.
Request a Quote
Emails go directly to customize@cehesteel.com - reply within 12h.