Steel A656 · grade
Steel A656-Gr70
Properties of the Gr70 condition, compared with the other A656 tempers.
Step below the popular Gr 80 when a little more bend ductility is needed.
What is A656-Gr70?
A656-Gr70 is A656 in the Gr70 grade — step below the popular Gr 80 when a little more bend ductility is needed. A656-Gr70 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 67% of steel grades. Elongation at break is 18% and the elastic modulus is 200 GPa (29 Msi). A656-Gr70 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; Gr70 is available on request or by drawing note.
Advantages
- Forms and bends easily — 70/100, better than 85% of steel grades
- Readily welded — 78/100, better than 78% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
A656-Gr70 properties
Typical room-temperature values for A656-Gr70 — 9 properties are specific to this condition; the rest are grade-level values shared by every A656 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
A656-Gr70 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).
Mechanical17
A656-Gr70 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 67% of steel grades. Elongation at break is 18% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
A656-Gr70 is rated for continuous service to 350°C (662 °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
A656-Gr70 conducts electricity at 9 % IACS, better than 70% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of A656-Gr70 takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
A656-Gr70's machinability is fair (50/100, worse than 53% of steel grades); weldability very good (78/100); 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 A656 tempers and conditions
A656 is also supplied in 9 other conditions. The full side-by-side table is on the A656 overview.
- HRDefaultStandard mill condition for A656 plate — pick for welded structural weight-saving parts up to ~25 mm.580 MPa yield · 215 HB
- Gr100Highest A656 strength level for maximum payload / minimum plate thickness; tightest forming and welding control.720 MPa yield · 25 HRC
- CRThin-gauge cold-reduced product for stamped high-strength panels; better surface and tighter gauge, lower ductility than hot-rolled.620 MPa yield · 230 HB
- Gr80The workhorse A656 grade for dump bodies, crane booms and trailer structures.580 MPa yield · 215 HB
- GalvanizedChoose when the part is exposed outdoors and cannot be repainted; zinc coating limits service temperature and post-weld appearance.570 MPa yield · 210 HB
- Gr70Step below the popular Gr 80 when a little more bend ductility is needed.520 MPa yield · 190 HB
- Gr60Mid-level HSLA plate for lightly loaded formed structures.450 MPa yield · 160 HB
- Gr50Lowest strength level — pick when formability and weldability outrank weight saving.380 MPa yield · 140 HB
Working with A656-Gr70
Is A656 easy to machine?
Machines like a 200–250 HB low-alloy steel — rigid setups, coated carbide, moderate speeds; drilling and plasma/laser cutting are routine but expect edge hardening on thermally cut faces.
Can A656 be welded?
Good weldability at CE < 0.45 — use low-hydrogen (E70xx–E80xx / matching flux-cored) consumables, control heat input and preheat 100–150 °C for Gr 80/100 or thicknesses over ~20 mm.
Can A656 be formed, bent or molded?
Designed for cold bending: bend transverse to rolling direction, use generous radii (≈3–4t for Gr 80, 4–5t for Gr 100) and allow for high springback.
What surface finishes work on A656?
No inherent corrosion resistance — shot blast to SA 2.5 then zinc-rich primer/paint, hot-dip galvanize, or metallize; not anodizable.
A656 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 maximum | ≤ 0.18 | 0.1 |
| Mn | ≤ 1.65 | 1.4 |
| Si | ≤ 0.6 | 0.3 |
| P | ≤ 0.03 | 0.01 |
| Slower S usual for Gr 80/100 with improved formability | ≤ 0.04 | 0.01 |
| VType 3 (vanadium) chemistry | 0.05 – 0.15 | 0.08 |
| TiType 7 (titanium) chemistry | ≤ 0.1 | 0.03 |
| Nboptional microalloy addition | ≤ 0.1 | — |
| Alfine-grain practice / deoxidation | ≥ 0.02 | 0.03 |
| N | ≤ 0.02 | 0.01 |
| Fe | balance | — |
A656-Gr70 — frequently asked
What is A656-Gr70 used for?
A656-Gr70 is typically used for crane booms, truck and trailer frames, dump truck bodies, hoppers and material-handling chutes, agricultural machinery structures and lifting and support beams. In short: high-strength low-alloy structural.
What is the yield strength of A656-Gr70?
A656-Gr70 has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 67% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is A656-Gr70 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machines like a 200–250 HB low-alloy steel — rigid setups, coated carbide, moderate speeds; drilling and plasma/laser cutting are routine but expect edge hardening on thermally cut faces.
Can A656-Gr70 be welded?
Yes — weldability is rated very good (78/100). Good weldability at CE < 0.45 — use low-hydrogen (E70xx–E80xx / matching flux-cored) consumables, control heat input and preheat 100–150 °C for Gr 80/100 or thicknesses over ~20 mm.
What surface finishes work on A656-Gr70?
No inherent corrosion resistance — shot blast to SA 2.5 then zinc-rich primer/paint, hot-dip galvanize, or metallize; not anodizable.
Can A656-Gr70 be formed, bent or molded?
Designed for cold bending: bend transverse to rolling direction, use generous radii (≈3–4t for Gr 80, 4–5t for Gr 100) and allow for high springback.
What is the maximum service temperature of A656-Gr70?
A656-Gr70 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A656-HR and A656-Gr50?
HR is the default condition — standard mill condition for A656 plate — pick for welded structural weight-saving parts up to ~25 mm. Gr50: lowest strength level — pick when formability and weldability outrank weight saving. Yield strength is 580 MPa in HR versus 380 MPa in Gr50.
Can FabDigit make parts in A656-Gr70?
Yes — A656-Gr70 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 A656/A656M — Hot-Rolled Structural Steel, HSLA Plate with Improved Formability — ASTM International (2018)
- 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)
- HSLA structural plate (A656 Gr 80) product data — Nucor / SSAB service-center literature (2023)
- GB/T 16270 (comparison grades Q550/Q690) — SAC (2009)
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.