Steel Q345R
GB Q345R
Q345R is the Chinese GB/T 713 low-alloy pressure-vessel plate grade (C–Mn–Si, killed and fine-grained), the workhorse material for boilers, separators, storage tanks and heat-exchanger shells in China; it is roughly equivalent in duty to ASTM A516 Gr.70 / EN P355GH.
Values for the HR condition
Q345R tempers and conditions
Q345R is supplied in 3 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Normalized | Mandatory for thick plate (>36 mm) and low-temperature/impact-critical vessels; refines grain and raises toughness uniformity. | 360 | 545 | 26 | 155 HB | — |
HRDefault Hot rolled | Default stock condition for plate up to ~36 mm; cheapest and covers most vessel and tank work. | 370 | 550 | 24 | 160 HB | — |
Cold rolled | Only for thin sheet blanks and formed parts where a smoother surface and tighter thickness tolerance matter; higher strength but lower ductility and toughness than plate. | 470 | 600 | 16 | 11 HRC | 8.4 % IACS |
Supply forms, finishes and certifications
Ways Q345R is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Galvanized | Hot-dip zinc coated sheet/plate | Coating |
What is Q345R?
Q345R is the Chinese GB/T 713 low-alloy pressure-vessel plate grade (C–Mn–Si, killed and fine-grained), the workhorse material for boilers, separators, storage tanks and heat-exchanger shells in China; it is roughly equivalent in duty to ASTM A516 Gr.70 / EN P355GH. It is chosen for a guaranteed 345 MPa minimum yield with good weldability, notch toughness down to -20 °C and low cost. Limits are poor atmospheric/chemical corrosion resistance (needs paint, cladding or galvanizing), a design temperature ceiling around 400–475 °C where creep and graphitization intervene, and the need for normalizing above ~36 mm thickness to keep impact values. Q345R has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,440°C (2,624 °F). Q345R has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 70% of steel grades. Elongation at break is 24% and the elastic modulus is 206 GPa (29.9 Msi).
What is Q345R used for?
- Pressure-vessel shells and heads
- Welded boiler drums
- Storage tanks
- Heat-exchanger shells
- Separator and column bodies
- Nozzles and reinforcing pads
- Heavy welded structural frames
Advantages
- Easy to machine — 62/100, better than 89% of steel grades
- Forms and bends easily — 70/100, better than 86% of steel grades
- Readily welded — 85/100, better than 83% of steel grades
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
Q345R properties
Typical room-temperature values for Q345R-HR; bars are the position among steel grades.
Physical3
Q345R has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,440°C (2,624 °F).
Mechanical16
Q345R has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 70% of steel grades. Elongation at break is 24% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
Q345R is rated for continuous service to 400°C (752 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
Q345R conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of Q345R takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 22%.
Manufacturability8
Q345R's machinability is good (62/100, better than 89% of steel grades); weldability excellent (85/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. Q345R is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Q345R
Is Q345R easy to machine?
Cuts like ordinary C-Mn plate: uncoated carbide at 120–180 m/min, generous feed to avoid work hardening; gummy chips, so use coolant and sharp edges for drilling nozzle holes.
Can Q345R be welded?
Excellent weldability by SMAW/SAW/GMAW with J507/H08A-class consumables per NB/T 47015; preheat 100–150 °C above ~30 mm or in cold shops, PWHT 600–640 °C for thick or stress-critical vessels.
Can Q345R be formed, bent or molded?
Cold flanging and rolling of shells are routine (bend radius ≥2t); hot forming of heads at 900–1000 °C should be followed by normalizing to restore GB/T 713 impact values.
Manufacturability
The process limits FabDigit applies to Q345R. Every Q345R part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better62 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better70 / 100 |
|---|---|
| Weldability | Excellent85 / 100 |
| Bendable | Yes |
Q345R chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CGB/T 713-2014 | ≤ 0.2 | 0.18 |
| Si | ≤ 0.55 | 0.35 |
| Mn | 1.2 – 1.7 | 1.45 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.01 | 0.01 |
| Nbmicroalloying, optional | ≤ 0.05 | 0.02 |
| Vmicroalloying, optional | ≤ 0.05 | 0.02 |
| Timicroalloying, optional | ≤ 0.03 | 0.01 |
| Altotal Al, killed steel | ≥ 0.02 | 0.03 |
| Crresidual | ≤ 0.3 | 0.05 |
| Niresidual | ≤ 0.3 | 0.05 |
| Curesidual | ≤ 0.3 | 0.05 |
| Moresidual | ≤ 0.08 | 0.02 |
| Fe | balance |
What surface finishes work on Q345R?
Shot-blast to Sa2½ then epoxy/zinc-rich primer, or hot-dip galvanize for outdoor structures; internal surfaces are usually rubber-lined, glass-flake coated or stainless clad.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
How much does Q345R cost?
Q345R is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Q345R — frequently asked
What is Q345R used for?
Q345R is typically used for pressure-vessel shells and heads, welded boiler drums, storage tanks, heat-exchanger shells, separator and column bodies and nozzles and reinforcing pads. In short: pressure-vessel structural plate.
What is the yield strength of Q345R?
Q345R has a typical yield strength of 370 MPa (53.7 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 70% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is Q345R easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Cuts like ordinary C-Mn plate: uncoated carbide at 120–180 m/min, generous feed to avoid work hardening; gummy chips, so use coolant and sharp edges for drilling nozzle holes.
Can Q345R be welded?
Yes — weldability is rated excellent (85/100). Excellent weldability by SMAW/SAW/GMAW with J507/H08A-class consumables per NB/T 47015; preheat 100–150 °C above ~30 mm or in cold shops, PWHT 600–640 °C for thick or stress-critical vessels.
What surface finishes work on Q345R?
Shot-blast to Sa2½ then epoxy/zinc-rich primer, or hot-dip galvanize for outdoor structures; internal surfaces are usually rubber-lined, glass-flake coated or stainless clad.
Can Q345R be formed, bent or molded?
Cold flanging and rolling of shells are routine (bend radius ≥2t); hot forming of heads at 900–1000 °C should be followed by normalizing to restore GB/T 713 impact values.
What is the maximum service temperature of Q345R?
Q345R is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Q345R-HR and Q345R-CR?
HR is the default condition — default stock condition for plate up to ~36 mm; cheapest and covers most vessel and tank work. CR: only for thin sheet blanks and formed parts where a smoother surface and tighter thickness tolerance matter; higher strength but lower ductility and toughness than plate. Yield strength is 370 MPa in HR versus 470 MPa in CR.
How much does Q345R cost?
Q345R is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in Q345R?
Yes — Q345R is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- GB/T 713 Steel plates for boilers and pressure vessels (2014)
- GB/T 150.2 Pressure vessels — Materials — SAC (2011)
- NB/T 47015 Welding specification for pressure vessels (2011)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- worldsteel LCI data for steel plate — World Steel Association (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.