Steel A53 Grade B-N (Normalized)
Heat-treated state
ASTM A53 Grade B · UNS K02504
Supplementary condition for uniform fine-grain structure, better toughness and lower residual stress before bending or impact-tested service.
Values for the N condition
Other A53 Grade B tempers and conditions
A53 Grade B is listed in 4 conditions; see the grade overview at A53 Grade B.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
NThis page Normalized | Supplementary condition for uniform fine-grain structure, better toughness and lower residual stress before bending or impact-tested service. | 275 | 450 | 33 | 131 HB | 10 % IACS |
Type E | Lowest-cost route for larger diameters and thinner walls; weld seam is normalized locally, mechanicals match Grade B minima. | 295 | 460 | 28 | 140 HB | 10 % IACS |
S-HR-BLKDefault seamless, hot finished, black (plain end) | Default stock condition: hot-finished seamless black pipe for general pressure, mechanical and structural piping. | 300 | 470 | 30 | 143 HB | — |
Cold-drawn seamless | Choose for tight tolerance and smooth bore mechanical tubing; strength and hardness rise, ductility and bendability fall. | 390 | 500 | 16 | 170 HB | 10 % IACS |
What is A53 Grade B-N?
A53 Grade B-N is A53 Grade B heat treated to N — supplementary condition for uniform fine-grain structure, better toughness and lower residual stress before bending or impact-tested service. A53 Grade B-N has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 91% of steel grades. Elongation at break is 33% and the elastic modulus is 200 GPa (29 Msi). A53 Grade B-N 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). S-HR-BLK is the default condition FabDigit quotes; N is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 33%, better than 96% of steel grades
- Readily welded — 93/100, better than 95% of steel grades
- Forms and bends easily — 82/100, better than 94% of steel grades
- Conducts heat well — 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades
- Easy to machine — 63/100, better than 92% of steel grades
Limitations
- Low strength — 275 MPa (39.9 ksi), worse than 91% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
A53 Grade B-N properties
Typical room-temperature values for A53 Grade B-N; 23 are specific to this condition. Other listed values are A53 Grade B reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A53 Grade B-N 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
A53 Grade B-N has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 91% of steel grades. Elongation at break is 33% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
A53 Grade B-N is rated for continuous service to 425°C (797 °F). It conducts heat at 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
A53 Grade B-N conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of A53 Grade B-N takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
A53 Grade B-N's machinability is good (63/100, better than 92% of steel grades); weldability excellent (93/100); formability very good (82/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A53 Grade B-N
Is A53 Grade B easy to machine?
Machines and threads easily (NPT per ASME B1.20.1) at ~65 % of 1212; use sharp tooling and coolant since the low-carbon matrix is gummy and produces stringy chips.
Can A53 Grade B be welded?
Excellent weldability by SMAW/GTAW/GMAW with E6010/E7018 or ER70S-2/6 filler; no preheat needed below ~25 mm wall, but grind off galvanizing and provide fume extraction on coated pipe.
Can A53 Grade B be formed, bent or molded?
Cold bends readily to 3–5 D on a mandrel bender; hot bending or induction bending at 850–950 °C for tight radii, follow with normalizing if heavily strained.
What surface finishes work on A53 Grade B?
Supplied black (mill scale or varnish) or hot-dip galvanized to ASTM A123; otherwise blast to SA 2.5 and apply zinc-rich primer, epoxy or FBE coating — no anodizing possible.
A53 Grade B 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 |
|---|---|---|
| CType S and Type E, Grade B | ≤ 0.3 | 0.2 |
| Mn | ≤ 1.2 | 0.9 |
| P | ≤ 0.05 | 0.02 |
| S | ≤ 0.05 | 0.02 |
| Cucombined alloy limit applies | ≤ 0.4 | 0.15 |
| Ni | ≤ 0.4 | 0.1 |
| Cr | ≤ 0.4 | 0.1 |
| Mo | ≤ 0.15 | 0.03 |
| V | ≤ 0.08 | 0.02 |
| Fe | balance | — |
A53 Grade B-N — frequently asked
What is A53 Grade B-N used for?
A53 Grade B-N is typically used for water piping, structural pipe, low-pressure lines and fencing/scaffolding tube. In short: low-cost general-purpose pipe; threadable and galvanizable; seamless or welded supply.
What is the yield strength of A53 Grade B-N?
A53 Grade B-N has a typical yield strength of 275 MPa (39.9 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 91% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A53 Grade B-N easy to machine?
Reasonably — machinability is rated good (63/100, better than 92% of steel grades). Machines and threads easily (NPT per ASME B1.20.1) at ~65 % of 1212; use sharp tooling and coolant since the low-carbon matrix is gummy and produces stringy chips.
Can A53 Grade B-N be welded?
Yes — weldability is rated excellent (93/100). Excellent weldability by SMAW/GTAW/GMAW with E6010/E7018 or ER70S-2/6 filler; no preheat needed below ~25 mm wall, but grind off galvanizing and provide fume extraction on coated pipe.
What surface finishes work on A53 Grade B-N?
Supplied black (mill scale or varnish) or hot-dip galvanized to ASTM A123; otherwise blast to SA 2.5 and apply zinc-rich primer, epoxy or FBE coating — no anodizing possible.
Can A53 Grade B-N be formed, bent or molded?
Cold bends readily to 3–5 D on a mandrel bender; hot bending or induction bending at 850–950 °C for tight radii, follow with normalizing if heavily strained.
What is the maximum service temperature of A53 Grade B-N?
A53 Grade B-N is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A53 Grade B S-HR-BLK and A53 Grade B S-CD?
S-HR-BLK is the default condition — default stock condition: hot-finished seamless black pipe for general pressure, mechanical and structural piping. S-CD: choose for tight tolerance and smooth bore mechanical tubing; strength and hardness rise, ductility and bendability fall. Yield strength is 300 MPa in S-HR-BLK versus 390 MPa in S-CD.
Sources
- ASTM A53/A53M Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless — ASTM International (2020)
- ASME B31.3 Process Piping / B31.1 Power Piping allowable stress tables — ASME (2022)
- ASME BPVC Section II Part D — Properties (Metric) — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook, machinability ratings — Industrial Press (2020)
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.