Steel FB780 · supply condition
Steel FB780-CR
Properties of the CR condition, compared with the other FB780 tempers.
Choose for thin gauges (0.8–2.0 mm) and better surface/thickness tolerance, e.g. seat structures and reinforcements.
What is FB780-CR?
FB780-CR is FB780 supplied in the CR condition — choose for thin gauges (0.8–2.0 mm) and better surface/thickness tolerance, e.g. seat structures and reinforcements. FB780-CR has a yield strength of 685 MPa (99.4 ksi) and a tensile strength of 835 MPa (121 ksi) — stronger than 80% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi). FB780-CR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F). HR is the default condition FabDigit quotes; CR is available on request or by drawing note.
Advantages
- High strength — 685 MPa (99.4 ksi), better than 80% of steel grades
- Readily welded — 78/100, better than 78% of steel grades
Limitations
- Limited ductility — 12%, worse than 84% of steel grades
FB780-CR properties
Typical room-temperature values for FB780-CR — 8 properties are specific to this condition; the rest are grade-level values shared by every FB780 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
FB780-CR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F).
Mechanical15
FB780-CR has a yield strength of 685 MPa (99.4 ksi) and a tensile strength of 835 MPa (121 ksi) — stronger than 80% of steel grades. Elongation at break is 12% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
FB780-CR is rated for continuous service to 350°C (662 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
FB780-CR 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 FB780-CR takes about 27 MJ of energy and emits 2.1 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 25%.
Manufacturability7
FB780-CR's machinability is fair (42/100, worse than 72% of steel grades); weldability very good (78/100); formability good (57/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other FB780 tempers and conditions
FB780 is also supplied in 3 other conditions. The full side-by-side table is on the FB780 overview.
- HRDefaultStandard supply form for chassis and wheel parts in 1.8–6 mm; best combination of 780 MPa strength and very high hole-expansion.660 MPa yield · 245 HB
- TMCPFor thicker sections (≈4–12 mm) where controlled rolling + accelerated cooling gives 780 MPa class strength with the best low-temperature toughness.700 MPa yield · 240 HB
- CRChoose for thin gauges (0.8–2.0 mm) and better surface/thickness tolerance, e.g. seat structures and reinforcements.685 MPa yield · 250 HB
- GalvanizedPick when the part is exposed to road salt and cannot be fully e-coated; zinc limits service temperature and slightly reduces spot-weld current window.650 MPa yield · 243 HB
Working with FB780-CR
Is FB780 easy to machine?
Drilling/trimming needs coated carbide and rigid setups; punching clearances ~12–15 % of thickness and sharp tools are essential to preserve the high hole-expansion advantage.
Can FB780 be welded?
Very good resistance spot, MAG and laser weldability thanks to low carbon and CE≈0.35; keep heat input moderate to limit HAZ softening, and use higher electrode force / adapted current for galvanized coil.
Can FB780 be formed, bent or molded?
Cold roll-form and stretch-flange well (HER typically 60–100 %), but total elongation is limited — expect large springback, so compensate die geometry and use overbending or post-stretch.
What surface finishes work on FB780?
No anodizing; protect by hot-dip zinc, zinc-nickel plating, phosphate + cathodic e-coat or powder paint; avoid hydrogen-charging pickling/plating routes on highly stressed parts.
FB780 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 |
|---|---|---|
| Clow carbon for weldability | ≤ 0.12 | 0.08 |
| Si | ≤ 0.6 | 0.3 |
| Mnhardenability / bainite formation | ≤ 2.2 | 1.7 |
| P | ≤ 0.03 | 0.01 |
| Slow S for hole-expansion | ≤ 0.01 | 0 |
| Aldeoxidation | 0.02 – 0.08 | 0.04 |
| Nbgrain refinement | ≤ 0.09 | 0.04 |
| TiNb+Ti+V total typically ≤0.22 | ≤ 0.12 | 0.05 |
| Voptional | ≤ 0.1 | — |
| Croptional, producer dependent | ≤ 0.6 | — |
| Mooptional, promotes bainite | ≤ 0.3 | — |
| N | ≤ 0.01 | 0 |
| Fe | balance | — |
FB780-CR — frequently asked
What is FB780-CR used for?
FB780-CR is typically used for automotive wheel discs, chassis arms and control arms, subframes, longitudinal members, suspension brackets with flanged holes and seat and cross-member structures. In short: high-strength FB auto sheet.
What is the yield strength of FB780-CR?
FB780-CR has a typical yield strength of 685 MPa (99.4 ksi) and a tensile strength of 835 MPa (121 ksi) — stronger than 80% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is FB780-CR easy to machine?
Not especially — machinability is rated fair (42/100, worse than 72% of steel grades). Drilling/trimming needs coated carbide and rigid setups; punching clearances ~12–15 % of thickness and sharp tools are essential to preserve the high hole-expansion advantage.
Can FB780-CR be welded?
Yes — weldability is rated very good (78/100). Very good resistance spot, MAG and laser weldability thanks to low carbon and CE≈0.35; keep heat input moderate to limit HAZ softening, and use higher electrode force / adapted current for galvanized coil.
What surface finishes work on FB780-CR?
No anodizing; protect by hot-dip zinc, zinc-nickel plating, phosphate + cathodic e-coat or powder paint; avoid hydrogen-charging pickling/plating routes on highly stressed parts.
Can FB780-CR be formed, bent or molded?
Cold roll-form and stretch-flange well (HER typically 60–100 %), but total elongation is limited — expect large springback, so compensate die geometry and use overbending or post-stretch.
What is the maximum service temperature of FB780-CR?
FB780-CR 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 FB780-HR and FB780 TMCP?
HR is the default condition — standard supply form for chassis and wheel parts in 1.8–6 mm; best combination of 780 MPa strength and very high hole-expansion. TMCP: for thicker sections (≈4–12 mm) where controlled rolling + accelerated cooling gives 780 MPa class strength with the best low-temperature toughness. Yield strength is 660 MPa in HR versus 700 MPa in TMCP.
Can FabDigit make parts in FB780-CR?
Yes — FB780-CR is available for sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- VDA 239-100 Sheet Steel for Cold Forming (HR/CR ...-FB grades) — VDA (2016)
- EN 10338 Hot rolled and cold rolled uncoated products of multiphase steels for cold forming — CEN (2015)
- Advanced High-Strength Steels Application Guidelines v7 — WorldAutoSteel (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Automotive hot-rolled ferritic-bainitic (FB) steel coil datasheets — Baosteel / POSCO / ArcelorMittal (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.