Steel 55Cr3
EN 55Cr3
55Cr3 (1.7176) is a hot-rolled chromium alloyed spring steel to EN 10089, essentially the European counterpart of SAE 5155/AISI 5155, used for leaf springs, torsion bars, stabiliser bars and heavy coil springs.
Values for the Annealed condition
55Cr3 tempers and conditions
55Cr3 is supplied in 8 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | 1.7176 annealed to globular carbides — the softest delivery state, used for cold heading, cold extrusion and heavy machining before hardening. | 380 | 640 | 22 | 190 HB | 45 W/m·K |
High Shearability | 1.7176 annealed to a capped hardness so that bar and coil can be cold sheared/cropped cleanly before forming and hardening. | 430 | 730 | 18 | 215 HB | 44 W/m·K |
AnnealedDefault soft (spheroidise) annealed bar | Stock condition for machining, cold forming and pre-heat-treat blanks; hardness capped at 248 HB by EN 10089. | 480 | 800 | 16 | 20 HRC | 7.8 % IACS |
Carburized and hardened | 1.7176 bar supplied heat treated to a specified core hardness band, giving uniform medium-high strength for further machining or induction/case work. | 550 | 870 | 14 | 25 HRC | 43 W/m·K |
as hot rolled bar / flat (mill edge) | Cheapest supply form for leaf-spring flats and coil-spring bar that will be austenitised by the spring maker. | 570 | 950 | 12 | 30 HRC | 7.8 % IACS |
normalised | Used to homogenise forgings and refine grain before hardening; more uniform than as-rolled. | 600 | 950 | 13 | 29 HRC | 7.8 % IACS |
cold drawn / peeled bar (annealed then drawn) | Choose for close diameter tolerance and better surface on torsion-bar and small spring blanks before hardening. | 750 | 950 | 8 | 30 HRC | 7.8 % IACS |
Quenched and tempered | Standard service condition for leaf springs, stabiliser bars and torsion bars: austenitise ~850 °C, oil quench, temper 400–480 °C. | 1,450 | 1,620 | 8 | 46 HRC | — |
What is 55Cr3?
55Cr3 (1.7176) is a hot-rolled chromium alloyed spring steel to EN 10089, essentially the European counterpart of SAE 5155/AISI 5155, used for leaf springs, torsion bars, stabiliser bars and heavy coil springs. The ~0.55 % C with ~0.8 % Cr gives deep, reliable oil hardenability and high tempered strength (typically 1500–1800 MPa at 45–50 HRC) with good sag/relaxation resistance. It is not corrosion resistant, has poor weldability and limited toughness at spring hardness, so it must be shot-peened and surface-protected in service and formed in the annealed or hot-rolled state. 55Cr3 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). 55Cr3 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 59% of steel grades. Elongation at break is 16% and the elastic modulus is 206 GPa (29.9 Msi).
What is 55Cr3 used for?
- Leaf springs
- Heavy coil springs
- Torsion bars
- Stabiliser (anti-roll) bars
- Spring clips and retainers
- Agricultural tine springs
Limitations
- Difficult to weld — 25/100, worse than 77% of steel grades
55Cr3 properties
Typical room-temperature values for 55Cr3-Annealed; bars are the position among steel grades.
Physical3
55Cr3 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical17
55Cr3 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 59% of steel grades. Elongation at break is 16% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
55Cr3 is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
55Cr3 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental2
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 55Cr3 takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 30%.
Manufacturability7
55Cr3's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (25/100); formability fair (45/100).
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. 55Cr3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 55Cr3
Is 55Cr3 easy to machine?
Machine in the annealed (+A) state with rigid setups and carbide tooling; at 45–50 HRC only grinding, hard turning with CBN or EDM is practical.
Can 55Cr3 be welded?
Effectively unweldable for structural use (Ceq ≈ 0.85); if unavoidable, preheat 300–350 °C, low-hydrogen consumables and immediate post-weld temper, then re-heat-treat.
Can 55Cr3 be formed, bent or molded?
Coil and bend hot (850–1050 °C) or in the annealed condition; harden from ~840–860 °C in oil and temper 400–480 °C, then stress-relieve set springs at ~250–300 °C.
Manufacturability
The process limits FabDigit applies to 55Cr3. Every 55Cr3 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair50 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better45 / 100 |
|---|---|
| Weldability | Fair25 / 100 |
| Bendable | Yes |
55Cr3 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 |
|---|---|---|
| CEN 10089 | 0.52 – 0.59 | 0.55 |
| Si | 0.15 – 0.4 | 0.25 |
| Mn | 0.7 – 1 | 0.85 |
| Cr | 0.7 – 1 | 0.85 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on 55Cr3?
Always shot-peen loaded surfaces for fatigue life; protect by phosphate + epoxy/powder paint or zinc-rich coating — avoid acid pickling and standard electroplating without a 190–210 °C hydrogen bake-out.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 55Cr3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 55Cr3 cost?
55Cr3 is a standard-cost steel ($$), cheaper than about 71% 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.
55Cr3 — frequently asked
What is 55Cr3 used for?
55Cr3 is typically used for leaf springs, heavy coil springs, torsion bars, stabiliser (anti-roll) bars, spring clips and retainers and agricultural tine springs. In short: spring chromium bar.
What is the yield strength of 55Cr3?
55Cr3 has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 800 MPa (116 ksi) — stronger than 59% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 55Cr3 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the annealed (+A) state with rigid setups and carbide tooling; at 45–50 HRC only grinding, hard turning with CBN or EDM is practical.
Can 55Cr3 be welded?
Not readily — weldability is rated poor (25/100). Effectively unweldable for structural use (Ceq ≈ 0.85); if unavoidable, preheat 300–350 °C, low-hydrogen consumables and immediate post-weld temper, then re-heat-treat.
What surface finishes work on 55Cr3?
Always shot-peen loaded surfaces for fatigue life; protect by phosphate + epoxy/powder paint or zinc-rich coating — avoid acid pickling and standard electroplating without a 190–210 °C hydrogen bake-out.
Can 55Cr3 be formed, bent or molded?
Coil and bend hot (850–1050 °C) or in the annealed condition; harden from ~840–860 °C in oil and temper 400–480 °C, then stress-relieve set springs at ~250–300 °C.
What is the maximum service temperature of 55Cr3?
55Cr3 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 55Cr3 Annealed and 55Cr3-AC?
Annealed is the default condition — stock condition for machining, cold forming and pre-heat-treat blanks; hardness capped at 248 HB by EN 10089. AC: 1.7176 annealed to globular carbides — the softest delivery state, used for cold heading, cold extrusion and heavy machining before hardening. Yield strength is 480 MPa in Annealed versus 380 MPa in AC.
How much does 55Cr3 cost?
55Cr3 is a standard-cost steel ($$), cheaper than about 71% 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.
Can FabDigit make parts in 55Cr3?
Yes — 55Cr3 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10089 — Hot rolled steels for quenched and tempered springs — CEN (2002)
- SAE J404 / J1397 — Chemical compositions and mechanical properties of SAE alloy steels (5155) — SAE International (2009)
- GB/T 1222 (2016)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Spring Design Manual (HS-795) — SAE International (1996)
- Spring steel bar and flat bar grade data (55Cr3 / 1.7176) — European long-products mills (2023)
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.