Steel Q345R · finish state
Steel Q345R Galvanized
Properties of the Galvanized condition, compared with the other Q345R tempers.
Choose when the part is exposed to weather and cannot be repainted; zinc coating limits service temperature and complicates welding.
What is Q345R Galvanized?
Q345R Galvanized is Q345R supplied in the Galvanized condition — choose when the part is exposed to weather and cannot be repainted; zinc coating limits service temperature and complicates welding. Q345R Galvanized 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 22% and the elastic modulus is 206 GPa (29.9 Msi). Q345R Galvanized 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). HR is the default condition FabDigit quotes; Galvanized is available on request or by drawing note.
Advantages
- Good corrosion resistance — 40/100, better than 98% of steel grades
- Easy to machine — 62/100, better than 89% of steel grades
- Forms and bends easily — 70/100, better than 85% of steel grades
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
Q345R Galvanized properties
Typical room-temperature values for Q345R Galvanized — 9 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 Galvanized 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 Galvanized 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 22% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
Q345R Galvanized is rated for continuous service to 200°C (392 °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 Galvanized conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), better than 98% of steel grades.
Sustainability4
Producing a kilogram of Q345R Galvanized 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 Galvanized's machinability is good (62/100, better than 89% of steel grades); weldability good (55/100); formability very good (70/100).
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 Galvanized
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 Galvanized — frequently asked
What is Q345R Galvanized used for?
Q345R Galvanized 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 Galvanized?
Q345R Galvanized 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 Galvanized 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 Galvanized be welded?
Yes — weldability is rated good (55/100). 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 Galvanized?
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 Galvanized 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 Galvanized?
Q345R Galvanized is rated for continuous use to about 200°C (392 °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 Galvanized?
Yes — Q345R Galvanized 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.