Steel 1055
AISI/SAE 1055 · UNS G10550
1055 is a plain medium-carbon steel at the top of the range (UNS G10550; C55, 1.0535, 55) with about 0.55 % C, hardened by quench-and-temper or bainitic treatment.
Reference datasheet — 1055 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 HR condition
1055 tempers and conditions
1055 is supplied in 11 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Use when severe cold heading, bending or deep drawing of the 0.55 % C steel is required. | 320 | 590 | 28 | 174 HB | 9.8 % IACS |
Solution annealed | Softest condition for heavy machining or cold forming before hardening. | 330 | 640 | 23 | 187 HB | — |
HRDefault Hot rolled | Standard as-rolled bar/plate/coil for parts that will be machined and then heat treated. | 370 | 660 | 12 | 192 HB | — |
Normalized | Refines grain and homogenizes forgings/hot-rolled stock before machining or hardening. | 420 | 725 | 19 | 217 HB | — |
Cold drawn | Pick for close-tolerance, bright, straight bar with higher yield strength and better surface finish than hot rolled. | 565 | 660 | 11 | 197 HB | — |
Q&T 540 °C | General quenched-and-tempered structural condition where toughness outweighs hardness. | 630 | 820 | 19 | 24 HRC | — |
Q&T 425 °C | Spring-temper style balance of strength and toughness for leaf springs and shafts. | 740 | 965 | 15 | 37 HRC | — |
Q&T 315 °C | High hardness with a little more toughness — hand tools, wear plates, cutters. | 800 | 1,090 | 11 | 46 HRC | — |
Q&T 205 °C | Maximum wear resistance for knives, chisels and cutting edges in thin sections. | 880 | 1,240 | 8 | 52 HRC | 46 W/m·K |
Hardened and blue tempered spring strip | Ready-to-use spring temper coil/strip for flat springs, clips, saw blades and shim stock. | 1,300 | 1,500 | 3 | 46 HRC | — |
As-quenched | Intermediate condition only — maximum hardness but brittle and crack-prone; temper immediately. | 1,600 | 2,000 | 1 | 63 HRC | 7.5 % IACS |
What is 1055?
1055 is a plain medium-carbon steel at the top of the range (UNS G10550; C55, 1.0535, 55) with about 0.55 % C, hardened by quench-and-temper or bainitic treatment. It is chosen for hardness and wear resistance in bar and strip for hand tools, blades and springs; the default condition gives 370 MPa yield, 660 MPa tensile, 12 % elongation and 192 HB, with tempering options at 205, 315, 425 and 540 °C. Weldability is poor, formability is limited unless spheroidized, and there is no corrosion resistance; service is capped near 400 °C. 1050 covers similar duty at slightly lower hardness. 1055 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). 1055 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 70% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
What is 1055 used for?
- hand tools
- blades
- springs
- agricultural parts
- wear plates
Advantages
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
Limitations
- Limited ductility — 12%, worse than 84% of steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
1055 properties
Typical room-temperature values for 1055-HR; bars are the position among steel grades.
Physical3
1055 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
1055 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 70% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
1055 is rated for continuous service to 400°C (752 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
1055 conducts electricity at 9.5 % IACS, better than 75% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 1055 takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 30%.
Manufacturability8
1055's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (28/100); formability fair (35/100).
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. 1055 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 1055
Is 1055 easy to machine?
Machine in the annealed/spheroidized or hot-rolled state at ~55 % of 1212 speed with rigid setups and carbide tooling; hardened parts above 45 HRC need grinding.
Can 1055 be welded?
Poor weldability at 0.55 % C — use low-hydrogen consumables, 200–300 °C preheat, interpass control and immediate post-weld temper; avoid welding on hardened parts.
Can 1055 be formed, bent or molded?
Cold form only from annealed/spheroidized stock with generous bend radii; otherwise hot form at 850–1100 °C and normalize afterwards.
1055 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 |
|---|---|---|
| CSAE J403 / ASTM A29 heat analysis | 0.5 – 0.6 | 0.55 |
| Mn | 0.6 – 0.9 | 0.75 |
| Sitypical for killed bar; not specified for all product forms | 0.15 – 0.35 | 0.25 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.05 | 0.03 |
| Fe | balance |
What surface finishes work on 1055?
No corrosion resistance bare — protect with black oxide, phosphate + oil, zinc plating (bake to avoid hydrogen embrittlement above 40 HRC) or paint; polishes well when hardened.
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 1055 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G10550
- Similar grades
- C551.053555
How much does 1055 cost?
1055 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.
1055 — frequently asked
What is 1055 used for?
1055 is typically used for hand tools, blades, springs, agricultural parts and wear plates. In short: spring and blade carbon steel; harder than 1045; low weldability rating.
What is the yield strength of 1055?
1055 has a typical yield strength of 370 MPa (53.7 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 70% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 1055 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the annealed/spheroidized or hot-rolled state at ~55 % of 1212 speed with rigid setups and carbide tooling; hardened parts above 45 HRC need grinding.
Can 1055 be welded?
Not readily — weldability is rated poor (28/100). Poor weldability at 0.55 % C — use low-hydrogen consumables, 200–300 °C preheat, interpass control and immediate post-weld temper; avoid welding on hardened parts.
What surface finishes work on 1055?
No corrosion resistance bare — protect with black oxide, phosphate + oil, zinc plating (bake to avoid hydrogen embrittlement above 40 HRC) or paint; polishes well when hardened.
Can 1055 be formed, bent or molded?
Cold form only from annealed/spheroidized stock with generous bend radii; otherwise hot form at 850–1100 °C and normalize afterwards.
What is the maximum service temperature of 1055?
1055 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 1055-HR and 1055-AQ?
HR is the default condition — standard as-rolled bar/plate/coil for parts that will be machined and then heat treated. AQ: intermediate condition only — maximum hardness but brittle and crack-prone; temper immediately. Yield strength is 370 MPa in HR versus 1,600 MPa in AQ.
How much does 1055 cost?
1055 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
- 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/A682M – Steel, Strip, High-Carbon, Cold-Rolled, Spring Quality — ASTM (2018)
- 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)
- EN 10083-2 / DIN 17200 – C55 (1.0535) — CEN (2006)
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.