Steel 1084 · hardness band
Steel 1084 Q&T 55-58 HRC
Properties of the Q&T 55-58 HRC condition, compared with the other 1084 tempers.
Standard knife/blade heat treat: maximum edge retention and hardness, minimal toughness margin.
What is 1084 Q&T 55-58 HRC?
1084 Q&T 55-58 HRC is 1084 heat treated to Q&T 55-58 HRC — standard knife/blade heat treat: maximum edge retention and hardness, minimal toughness margin. 1084 Q&T 55-58 HRC has a yield strength of 1,500 MPa (218 ksi) and a tensile strength of 1,950 MPa (283 ksi) — stronger than 97% of steel grades. Elongation at break is 3% and the elastic modulus is 205 GPa (29.7 Msi). 1084 Q&T 55-58 HRC 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; Q&T 55-58 HRC is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 85/100, better than 99% of steel grades
- High strength — 1,500 MPa (218 ksi), better than 97% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
- High electrical conductivity — 9.6 % IACS, better than 77% of steel grades
Limitations
- Difficult to machine — 8/100, worse than 100% of steel grades
- Limited formability — 3/100, worse than 100% of steel grades
- Limited ductility — 3%, worse than 99% of steel grades
- Limited service temperature — 150°C (302 °F), worse than 99% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
1084 Q&T 55-58 HRC properties
Typical room-temperature values for 1084 Q&T 55-58 HRC — 14 properties are specific to this condition; the rest are grade-level values shared by every 1084 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
1084 Q&T 55-58 HRC 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).
Mechanical13
1084 Q&T 55-58 HRC has a yield strength of 1,500 MPa (218 ksi) and a tensile strength of 1,950 MPa (283 ksi) — stronger than 97% of steel grades. Elongation at break is 3% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
1084 Q&T 55-58 HRC is rated for continuous service to 150°C (302 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
1084 Q&T 55-58 HRC conducts electricity at 9.6 % IACS, better than 77% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (8/100), worse than 99% of steel grades.
Sustainability4
Producing a kilogram of 1084 Q&T 55-58 HRC 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
1084 Q&T 55-58 HRC's machinability is not recommended (8/100, worse than 100% of steel grades); weldability poor (20/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 1084 tempers and conditions
1084 is also supplied in 9 other conditions. The full side-by-side table is on the 1084 overview.
- HRDefaultCheapest stock form for forging, blade blanks and parts that will be re-heat-treated.585 MPa yield · 31 HRC
- Q&T 55-58 HRCStandard knife/blade heat treat: maximum edge retention and hardness, minimal toughness margin.1,500 MPa yield · 57 HRC
- Q&T 48-52 HRCBalance of hardness and shock resistance for cold chisels, punches, scrapers and heavy blades.1,280 MPa yield · 50 HRC
- Q&TGeneral-purpose hardened-and-tempered condition for springs, chisels and wear parts needing some toughness.1,000 MPa yield · 41 HRC
- CDTight tolerance, straight bar with raised yield strength for pins, punches and shafts.875 MPa yield · 31 HRC
- CRPrecision-thickness strip with good surface for saw blades, shims and spring clips.700 MPa yield · 240 HB
- NormalizedUse to refine forged grain structure and homogenize before hardening.525 MPa yield · 31 HRC
- SPA+CDGlobular-carbide spheroidized 1084 bar/wire finished by cold drawing — moderate strength with the best cold formability and machinability attainable in a eutectoid carbon steel.515 MPa yield · 183 HB
- AnnealedSoftest condition for machining, drilling and blanking before hardening.380 MPa yield · 187 HB
- SPAChoose for cold forming, deep drawing or heavy machining of high-carbon strip.350 MPa yield · 174 HB
Working with 1084 Q&T 55-58 HRC
Is 1084 easy to machine?
Machine in the annealed or spheroidized state (≈45–55 % of 1212) with rigid setups and carbide or coated HSS; above 45 HRC switch to grinding, EDM or CBN.
Can 1084 be welded?
Poor weldability — 0.85 % C gives hard, crack-sensitive martensite; if unavoidable, preheat 250–300 °C, use low-hydrogen filler and post-weld temper immediately.
Can 1084 be formed, bent or molded?
Hot forge 1050–850 °C then normalize; cold bending only in spheroidized/annealed strip with generous radii, never in hardened condition.
What surface finishes work on 1084?
Grinds and polishes to a fine finish but rusts quickly — protect with oil/wax, black oxide, phosphate, bluing, nickel or zinc plating; no anodizing.
1084 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 |
|---|---|---|
| Ceutectoid carbon level | 0.8 – 0.93 | 0.86 |
| Mn | 0.6 – 0.9 | 0.75 |
| Sinot specified in SAE J403; typical mill practice for killed steel | 0.1 – 0.35 | 0.2 |
| P | ≤ 0.04 | — |
| Smax (non-resulfurized grade) | ≤ 0.05 | — |
| Fe | balance | — |
1084 Q&T 55-58 HRC — frequently asked
What is 1084 Q&T 55-58 HRC used for?
1084 Q&T 55-58 HRC is typically used for knives, hand tools and springs. In short: stronger spring steel.
What is the yield strength of 1084 Q&T 55-58 HRC?
1084 Q&T 55-58 HRC has a typical yield strength of 1,500 MPa (218 ksi) and a tensile strength of 1,950 MPa (283 ksi) — stronger than 97% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 1084 Q&T 55-58 HRC easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Machine in the annealed or spheroidized state (≈45–55 % of 1212) with rigid setups and carbide or coated HSS; above 45 HRC switch to grinding, EDM or CBN.
Can 1084 Q&T 55-58 HRC be welded?
Not readily — weldability is rated poor (20/100). Poor weldability — 0.85 % C gives hard, crack-sensitive martensite; if unavoidable, preheat 250–300 °C, use low-hydrogen filler and post-weld temper immediately.
What surface finishes work on 1084 Q&T 55-58 HRC?
Grinds and polishes to a fine finish but rusts quickly — protect with oil/wax, black oxide, phosphate, bluing, nickel or zinc plating; no anodizing.
Can 1084 Q&T 55-58 HRC be formed, bent or molded?
Hot forge 1050–850 °C then normalize; cold bending only in spheroidized/annealed strip with generous radii, never in hardened condition.
What is the maximum service temperature of 1084 Q&T 55-58 HRC?
1084 Q&T 55-58 HRC is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 1084-HR and 1084-CD?
HR is the default condition — cheapest stock form for forging, blade blanks and parts that will be re-heat-treated. CD: tight tolerance, straight bar with raised yield strength for pins, punches and shafts. Yield strength is 585 MPa in HR versus 875 MPa in CD.
Can FabDigit make parts in 1084 Q&T 55-58 HRC?
Yes — 1084 Q&T 55-58 HRC 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
- SAE J403 — Chemical Compositions of SAE Carbon Steels — SAE International (2014)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- ASTM A682/A684 — High-Carbon Spring Steel Strip — ASTM (2019)
- ASM Handbook Vol.1: Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4: Heat Treating — ASM International (1991)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
- GB/T 1298 (T8/T9 comparison grades) — SAC (2008)
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.