Steel Q345R · supply condition · default condition
Steel Q345R-HR
Properties of the HR condition, compared with the other Q345R tempers.
Default stock condition for plate up to ~36 mm; cheapest and covers most vessel and tank work.
What is Q345R-HR?
Q345R-HR is Q345R supplied in the HR condition — default stock condition for plate up to ~36 mm; cheapest and covers most vessel and tank work. Q345R-HR 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). Q345R-HR 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).
Advantages
- Easy to machine — 62/100, better than 89% of steel grades
- Forms and bends easily — 70/100, better than 85% 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-HR properties
Typical room-temperature values for Q345R-HR — 11 properties are specific to this condition; the rest are grade-level values shared by every Q345R temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
Q345R-HR 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-HR 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-HR 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-HR 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-HR 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-HR'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.
Other Q345R tempers and conditions
Q345R is also supplied in 3 other conditions. The full side-by-side table is on the Q345R overview.
- HRDefaultDefault stock condition for plate up to ~36 mm; cheapest and covers most vessel and tank work.370 MPa yield · 160 HB
- CROnly 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 MPa yield · 185 HB
- GalvanizedChoose when the part is exposed to weather and cannot be repainted; zinc coating limits service temperature and complicates welding.370 MPa yield · 160 HB
- NMandatory for thick plate (>36 mm) and low-temperature/impact-critical vessels; refines grain and raises toughness uniformity.360 MPa yield · 155 HB
Working with Q345R-HR
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.
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.
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 | — |
Q345R-HR — frequently asked
What is Q345R-HR used for?
Q345R-HR 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-HR?
Q345R-HR 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 4 listed tempers.
Is Q345R-HR 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-HR 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-HR?
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-HR 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-HR?
Q345R-HR 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.
Can FabDigit make parts in Q345R-HR?
Yes — Q345R-HR is available for CNC machining and sheet metal with instant online pricing. 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.