Steel A204 · grade
Steel A204 Gr.A
Properties of the Gr.A condition, compared with the other A204 tempers.
Choose Grade A when maximum weldability and ductility matter more than allowable stress.
What is A204 Gr.A?
A204 Gr.A is A204 in the Gr.A grade — choose Grade A when maximum weldability and ductility matter more than allowable stress. A204 Gr.A has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 88% of steel grades. Elongation at break is 27% and the elastic modulus is 205 GPa (29.7 Msi). A204 Gr.A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). HR is the default condition FabDigit quotes; Gr.A is available on request or by drawing note.
Advantages
- Easy to machine — 62/100, better than 89% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
- Ductile — tolerates forming and impact — 27%, better than 85% of steel grades
- Forms and bends easily — 70/100, better than 85% of steel grades
- Readily welded — 80/100, better than 80% of steel grades
Limitations
- Low strength — 290 MPa (42.1 ksi), worse than 88% of steel grades
A204 Gr.A properties
Typical room-temperature values for A204 Gr.A — 33 properties are specific to this condition; the rest are grade-level values shared by every A204 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
A204 Gr.A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical14
A204 Gr.A has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 88% of steel grades. Elongation at break is 27% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A204 Gr.A is rated for continuous service to 450°C (842 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
A204 Gr.A conducts electricity at 8.2 % IACS, better than 60% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of A204 Gr.A takes about 26 MJ of energy and emits 2.1 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 30%.
Manufacturability8
A204 Gr.A's machinability is good (62/100, better than 89% of steel grades); weldability very good (80/100); 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 A204 tempers and conditions
A204 is also supplied in 7 other conditions. The full side-by-side table is on the A204 overview.
- HRDefaultStandard stocked condition for thinner A204 plate where as-rolled properties meet the grade minima.315 MPa yield · 160 HB
- Q&TUsed for thick sections or when the upper end of the tensile range plus high toughness is required.405 MPa yield · 180 HB
- Gr.CUse where the thinnest possible shell is wanted; slightly higher carbon so welding controls are stricter.340 MPa yield · 163 HB
- Gr.BMost widely stocked A204 grade; default choice for boiler drums and elevated-temperature vessels.315 MPa yield · 152 HB
- Gr.AChoose Grade A when maximum weldability and ductility matter more than allowable stress.290 MPa yield · 140 HB
Working with A204 Gr.A
Is A204 easy to machine?
Machines like a 190 HB low-alloy steel — carbide tooling, moderate speeds, good chip control; slightly gummier than plain carbon steel due to Mo.
Can A204 be welded?
Readily welded with matching 0.5Mo consumables (E7018-A1 / ER80S-D2); preheat ~100–150 °C on thick plate and apply PWHT at 620–680 °C per code.
Can A204 be formed, bent or molded?
Cold-form only mild radii; hot form heads at 900–1000 °C and re-normalize afterwards to restore properties.
What surface finishes work on A204?
Blast and paint, phosphate or metallize; no anodizing — for corrosive service use stainless weld overlay or roll-bonded clad plate.
A204 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 |
|---|---|---|
| CGr.A ≤0.25, Gr.B ≤0.27, Gr.C ≤0.28 (thickness dependent) | ≤ 0.27 | 0.2 |
| Mnheat analysis max; Gr.C to 0.90 | ≤ 0.9 | 0.7 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.01 |
| Si | 0.15 – 0.4 | 0.25 |
| Mocreep-strengthening addition | 0.45 – 0.6 | 0.5 |
| Fe | balance | — |
A204 Gr.A — frequently asked
What is A204 Gr.A used for?
A204 Gr.A is typically used for boilers, storage tanks and refinery vessels. In short: molybdenum pressure plate.
What is the yield strength of A204 Gr.A?
A204 Gr.A has a typical yield strength of 290 MPa (42.1 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 88% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is A204 Gr.A easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machines like a 190 HB low-alloy steel — carbide tooling, moderate speeds, good chip control; slightly gummier than plain carbon steel due to Mo.
Can A204 Gr.A be welded?
Yes — weldability is rated very good (80/100). Readily welded with matching 0.5Mo consumables (E7018-A1 / ER80S-D2); preheat ~100–150 °C on thick plate and apply PWHT at 620–680 °C per code.
What surface finishes work on A204 Gr.A?
Blast and paint, phosphate or metallize; no anodizing — for corrosive service use stainless weld overlay or roll-bonded clad plate.
Can A204 Gr.A be formed, bent or molded?
Cold-form only mild radii; hot form heads at 900–1000 °C and re-normalize afterwards to restore properties.
What is the maximum service temperature of A204 Gr.A?
A204 Gr.A is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in A204 Gr.A?
Yes — A204 Gr.A 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
- ASTM A204/A204M — Pressure Vessel Plates, Alloy Steel, Molybdenum — ASTM International (2019)
- ASME BPVC Section II Part A (SA-204) and Part D (allowable stresses, physical properties) — ASME (2023)
- EN 10028-2 (16Mo3) — Flat products for pressure purposes, creep-resisting steels — CEN (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13C / Vol.19 — Corrosion and Fatigue of steels — ASM International (2006)
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.