Steel A633 Grade C
ASTM A633 Grade C · GB Q355C
A633 Grade C is a normalized high-strength low-alloy structural plate with guaranteed notch toughness, broadly equivalent to S355J2 and Q355C and available normalized, in heavy section, normalized plus stress relieved, or with CVN testing at -40 °C.
Reference datasheet — A633 Grade C is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the N condition
A633 Grade C tempers and conditions
A633 Grade C is supplied in 4 conditions, soft to hard. N is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
N | Heavy normalized plate; A633 allows reduced strength levels above 65 mm thickness. | 350 | 490 | 24 | 150 HB | 9 % IACS |
Normalized then stress-relieved / tempered | Pick when heavy welding or cold forming demands residual-stress relief; slight strength drop, toughness retained. | 365 | 510 | 26 | 155 HB | 9 % IACS |
NDefault Normalized | Standard A633 Grade C supply condition — normalized plate meeting 345 MPa minimum yield with good low-temperature CVN. | 385 | 530 | 25 | 160 HB | — |
N + supplementary CVN | Order this when low-temperature notch toughness must be certified per A633 supplementary requirements (or S355J2 20 °C/-20 °C option). | 385 | 530 | 25 | 160 HB | 9 % IACS |
What is A633 Grade C?
A633 Grade C is a normalized high-strength low-alloy structural plate with guaranteed notch toughness, broadly equivalent to S355J2 and Q355C and available normalized, in heavy section, normalized plus stress relieved, or with CVN testing at -40 °C. Default properties are 385 MPa yield, 530 MPa tensile, 25 % elongation and 160 HB, with service to 400 °C, which suits welded structures and machinery frames operating in cold climates. It offers no corrosion resistance and must be coated, and hot forming above 900 °C requires re-normalizing to restore certified properties. A242 is the alternative when bare weathering exposure is wanted. A633 Grade C 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). A633 Grade C has a yield strength of 385 MPa (55.8 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 65% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
What is A633 Grade C used for?
- heavy machinery frames
- welded structures
- low-temperature service plate
Advantages
- Readily welded — 82/100, better than 81% of steel grades
- Forms and bends easily — 62/100, better than 78% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
A633 Grade C properties
Typical room-temperature values for A633 Grade C-N; bars are the position among steel grades.
Physical3
A633 Grade C 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).
Mechanical16
A633 Grade C has a yield strength of 385 MPa (55.8 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 65% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A633 Grade C is rated for continuous service to 400°C (752 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
A633 Grade C conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of A633 Grade C takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
A633 Grade C's machinability is good (58/100, better than 75% of steel grades); weldability very good (82/100); formability good (62/100).
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. A633 Grade C is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A633 Grade C
Is A633 Grade C easy to machine?
Machines like normalized C-Mn steel at ~60 % of 1212; use carbide, moderate speeds and positive rake, expect gummy chips at low feeds.
Can A633 Grade C be welded?
Excellent weldability by SMAW/GMAW/SAW/FCAW with E70/ER70S consumables; low carbon equivalent means preheat only for heavy sections (>40 mm) or high restraint, keep heat input moderate to preserve HAZ toughness.
Can A633 Grade C be formed, bent or molded?
Cold bends readily at 2–3 t inside radius transverse to rolling; hot forming above 900 °C requires re-normalizing to restore certified properties.
A633 Grade C 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 |
|---|---|---|
| Cheat analysis, ASTM A633 Grade C | ≤ 0.2 | 0.16 |
| Mn | 1.15 – 1.5 | 1.3 |
| Si | 0.15 – 0.5 | 0.3 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.01 |
| Nboptional micro-alloying / grain refinement by producer agreement | ≤ 0.05 | 0.02 |
| Voptional micro-alloying addition | ≤ 0.06 | |
| Algrain-refining / killed practice | ≈ 0.03 | 0.03 |
| Fe | balance |
What surface finishes work on A633 Grade C?
Blast to SA 2.5 and paint, hot-dip galvanize or metallize for corrosion protection; no anodizing, and phosphating is used before powder coat.
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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel A633 Grade C in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does A633 Grade C cost?
A633 Grade C is a budget-cost steel ($), cheaper than about 90% 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.
A633 Grade C — frequently asked
What is A633 Grade C used for?
A633 Grade C is typically used for heavy machinery frames, welded structures and low-temperature service plate. In short: notch-tough normalized HSLA plate; certified low-temperature toughness; S355J2 plate equivalent.
What is the yield strength of A633 Grade C?
A633 Grade C has a typical yield strength of 385 MPa (55.8 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 65% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A633 Grade C easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like normalized C-Mn steel at ~60 % of 1212; use carbide, moderate speeds and positive rake, expect gummy chips at low feeds.
Can A633 Grade C be welded?
Yes — weldability is rated very good (82/100). Excellent weldability by SMAW/GMAW/SAW/FCAW with E70/ER70S consumables; low carbon equivalent means preheat only for heavy sections (>40 mm) or high restraint, keep heat input moderate to preserve HAZ toughness.
What surface finishes work on A633 Grade C?
Blast to SA 2.5 and paint, hot-dip galvanize or metallize for corrosion protection; no anodizing, and phosphating is used before powder coat.
Can A633 Grade C be formed, bent or molded?
Cold bends readily at 2–3 t inside radius transverse to rolling; hot forming above 900 °C requires re-normalizing to restore certified properties.
What is the maximum service temperature of A633 Grade C?
A633 Grade C 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 A633 Grade C-N and A633 Grade C N-HEAVY?
N is the default condition — standard A633 Grade C supply condition — normalized plate meeting 345 MPa minimum yield with good low-temperature CVN. N-HEAVY: heavy normalized plate; A633 allows reduced strength levels above 65 mm thickness. Yield strength is 385 MPa in N versus 350 MPa in N-HEAVY.
How much does A633 Grade C cost?
A633 Grade C is a budget-cost steel ($), cheaper than about 90% 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.
Sources
- ASTM A633/A633M Standard Specification for Normalized High-Strength Low-Alloy Structural Steel Plates — ASTM International (2018)
- EN 10025-2 Hot rolled products of structural steels — Non-alloy structural steels (S355J2) — CEN (2019)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19: Fatigue and Fracture — ASM International (1996)
- AWS D1.1 Structural Welding Code — Steel — AWS (2020)
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.