Steel C55E
EN C55E · AISI/SAE 1055 · GB 55
C55E (1.1203, AISI 1055) is a medium-carbon non-alloy quality steel of about 0.55 % C used quenched and tempered or induction hardened where higher strength and wear resistance than C45 grades are required.
Reference datasheet — C55E 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 +QT condition
C55E tempers and conditions
C55E is supplied in 10 conditions, soft to hard. +QT is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest supply condition; choose for heavy machining, cold forming or as a pre-condition before hardening. | 340 | 620 | 20 | 190 HB | — |
Normalized | Uniform fine pearlitic structure for good machinability and predictable strength without quenching distortion. | 390 | 760 | 14 | 225 HB | — |
Hot rolled | Cheapest bar/plate condition for parts that will be re-heat-treated after machining or for low-duty use. | 400 | 720 | 15 | 210 HB | — |
Normalized and tempered | Pick when normalized strength is sufficient but residual stress and hardness scatter must be reduced before precision machining. | 400 | 740 | 15 | 215 HB | — |
+QTDefault Quenched and tempered | Standard engineering condition: best strength/toughness balance for shafts, keyed drive parts and wear plates up to ~40 mm section. | 550 | 850 | 14 | 24 HRC | — |
+QT + induction surface hardened | Tough Q&T core with a hard wear-resistant skin — the classic choice for journal areas of shafts, pins and rollers. | 560 | 870 | 12 | 58 HRC | — |
Stress relieved | Cold-drawn bar with residual stress removed to minimize bending/distortion during asymmetric machining. | 600 | 780 | 10 | 20 HRC | 9.5 % IACS |
Cold drawn | Close-tolerance bright bar with raised strength and good surface finish; use for shafts machined without further heat treatment. | 660 | 820 | 8 | 22 HRC | — |
Q&T to 28–32 HRC | Ordered when a specified through-hardness is required for gear blanks, spline shafts and moderately loaded wear parts. | 740 | 950 | 12 | 30 HRC | — |
Q&T to 40–45 HRC | High-hardness condition for blades, wear strips, hand-tool bodies and springs in sections under ~25 mm; toughness drops sharply. | 1,130 | 1,350 | 9 | 42 HRC | 44 W/m·K |
What is C55E?
C55E (1.1203, AISI 1055) is a medium-carbon non-alloy quality steel of about 0.55 % C used quenched and tempered or induction hardened where higher strength and wear resistance than C45 grades are required. Default +QT properties are 550 MPa yield, 850 MPa tensile, 14 % elongation and 250 HB (24 HRC), with +A, +AR, +N, +NT, QT 28–32 HRC, QT 40–45 HRC, +QT+IH, +C and +SR conditions on file. Weldability is poor (CE ≈ 0.7), cold formability is limited, service tops out near 300 °C and the steel has no corrosion resistance; where welding is needed, step back to C35E. C55E has a density of 7.84 g/cm³ (0.283 lb/in³), lighter than 78% of steel grades. It melts at 1,420°C (2,588 °F). C55E has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 71% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
What is C55E used for?
- Machine shafts
- Gears
- Springs
- Wear parts
Limitations
- Low fracture toughness — 50 MPa·√m (45.5 ksi·√in), worse than 86% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
C55E properties
Typical room-temperature values for C55E-+QT; bars are the position among steel grades.
Physical3
C55E has a density of 7.84 g/cm³ (0.283 lb/in³), lighter than 78% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
C55E has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 71% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
C55E is rated for continuous service to 300°C (572 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
C55E conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of C55E takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
C55E's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (25/100); formability poor (25/100).
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. C55E is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C55E
Is C55E easy to machine?
Machine in +A or +N (≈55–65 % of 1212); above 30 HRC use coated carbide, rigid setups and reduced feeds — grind above 45 HRC.
Can C55E be welded?
Poor weldability (CE ≈ 0.7): preheat 250–350 °C, low-hydrogen consumables, slow cooling and post-weld tempering to avoid HAZ martensite cracking.
Can C55E be formed, bent or molded?
Cold forming limited to gentle bends in the annealed condition (r ≥ 2–3 t); hot forge at 1100–850 °C then normalize.
C55E 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 |
|---|---|---|
| C | 0.52 – 0.6 | 0.55 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| PE-quality: controlled P | ≤ 0.03 | |
| SE-quality: controlled S | ≤ 0.04 | |
| Crresidual | ≤ 0.4 | |
| Niresidual | ≤ 0.4 | |
| Moresidual | ≤ 0.1 | |
| Cr+Mo+Nisum of residuals per EN 10083-2 | ≤ 0.63 | |
| Fe | balance |
What surface finishes work on C55E?
No natural corrosion resistance — protect with black oxide, phosphate + oil, zinc/nickel plating or paint; hardened surfaces polish and hard-chrome plate well.
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 C55E in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- AISI / SAE
- 1055
- EN / DIN / Werkstoff-Nr.
- 1.1203
- GB (China)
- 55
How much does C55E cost?
C55E is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C55E — frequently asked
What is C55E used for?
C55E is typically used for machine shafts, gears, springs and wear parts. In short: higher strength than C45; spring and wear grade; poor weldability at 0.55 % C.
What is the yield strength of C55E?
C55E has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 71% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is C55E easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in +A or +N (≈55–65 % of 1212); above 30 HRC use coated carbide, rigid setups and reduced feeds — grind above 45 HRC.
Can C55E be welded?
Not readily — weldability is rated poor (25/100). Poor weldability (CE ≈ 0.7): preheat 250–350 °C, low-hydrogen consumables, slow cooling and post-weld tempering to avoid HAZ martensite cracking.
What surface finishes work on C55E?
No natural corrosion resistance — protect with black oxide, phosphate + oil, zinc/nickel plating or paint; hardened surfaces polish and hard-chrome plate well.
Can C55E be formed, bent or molded?
Cold forming limited to gentle bends in the annealed condition (r ≥ 2–3 t); hot forge at 1100–850 °C then normalize.
What is the maximum service temperature of C55E?
C55E is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does C55E cost?
C55E is a budget-cost steel ($), 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
- EN 10083-2: Steels for quenching and tempering — Non-alloy steels — CEN (2006)
- EN 10277 / EN 10025 bright and hot-rolled product conditions — CEN (2018)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys (AISI 1055) — ASM International (1990)
- Machinery's Handbook, machinability ratings — Industrial Press (2020)
- ISO 18265 hardness conversion tables — ISO (2013)
- Mysteel / carbon bar price series and 1688 — Mysteel, SMM (2026)
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.