Stainless Steel 7Cr17
EN 7Cr17
7Cr17 is a high-carbon (about 0.7 %C), 17 % chromium martensitic stainless steel in the 410/420/440 family, strengthened by quenching and tempering rather than by alloy additions.
Reference datasheet — 7Cr17 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 A condition
7Cr17 tempers and conditions
7Cr17 is supplied in 7 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard supply condition for machining, blanking and blade grinding before hardening. | 415 | 740 | 20 | 220 HB | — |
Hot rolled | Mill supply form for thick bar and plate that will be machined and heat treated by the user. | 430 | 760 | 18 | 20 HRC | 2.9 % IACS |
Cold rolled, half hard strip | Work-hardened strip for stamped blanks and springy parts that will be hardened later. | 750 | 950 | 6 | 30 HRC | 2.9 % IACS |
Q&T ~44–48 HRC | Tougher setting for scissors, shear blades and mechanical parts where chipping must be avoided. | 1,250 | 1,450 | 8 | 46 HRC | — |
Q&T 50–53 HRC | Common kitchen-knife and kitchenware hardness: good balance of edge holding and toughness. | 1,500 | 1,700 | 6 | 52 HRC | — |
Q&T 54–57 HRC | Maximum practical hardness for 7Cr17: best edge retention, lowest toughness and corrosion margin. | 1,650 | 1,850 | 4 | 56 HRC | — |
Hardened + sub-zero + temper | Adds a −75 °C sub-zero step to convert retained austenite for maximum hardness and dimensional stability. | 1,700 | 1,900 | 3 | 57 HRC | 2.8 % IACS |
What is 7Cr17?
7Cr17 is a high-carbon (about 0.7 %C), 17 % chromium martensitic stainless steel in the 410/420/440 family, strengthened by quenching and tempering rather than by alloy additions. In the annealed condition it runs roughly 415 MPa yield, 740 MPa tensile, 20 % elongation and 220 HB (96 HRB), and it is supplied as strip, bar and blanked profiles for cutlery and hardenable mechanical parts. Limits are a 500 °C maximum service temperature, moderate corrosion resistance (score 45), poor weldability and machining restricted to the annealed state. Where better edge retention or toughness is required, 7Cr17MoV or 420HC are the nearest alternatives. 7Cr17 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,370°C (2,498 °F). 7Cr17 has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 740 MPa (107 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 200 GPa (29 Msi).
What is 7Cr17 used for?
- kitchen knives
- kitchenware
- mechanical fittings
- shafts
Advantages
- Low embodied carbon — 3.5 kg CO₂/kg, better than 88% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
- Conducts heat well — 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades
Limitations
- Difficult to weld — 20/100, worse than 95% of stainless steel grades
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 88% of stainless steel grades
- Needs corrosion protection — 45/100, worse than 85% of stainless steel grades
- Limited ductility — 20%, worse than 79% of stainless steel grades
7Cr17 properties
Typical room-temperature values for 7Cr17-A; bars are the position among stainless steel grades.
Physical3
7Cr17 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical16
7Cr17 has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 740 MPa (107 ksi) — stronger than 62% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
7Cr17 is rated for continuous service to 500°C (932 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).
Electrical3
7Cr17 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 85% of stainless steel grades.
Sustainability4
Producing a kilogram of 7Cr17 takes about 45 MJ of energy and emits 3.5 kg of CO₂ — less than 91% of stainless steel grades. Typical recycled content is 50%.
Manufacturability8
7Cr17's machinability is fair (42/100, better than 79% of stainless steel grades); weldability poor (20/100); formability poor (30/100).
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 stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 7Cr17 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 7Cr17
Is 7Cr17 easy to machine?
Machine only in the annealed state with sharp carbide tooling, rigid setups and generous coolant; hardened parts require grinding, EDM or CBN.
Can 7Cr17 be welded?
Poor weldability — 0.7 %C martensitic; if unavoidable preheat 200–300 °C, use 309/410NiMo filler and temper immediately after welding.
Can 7Cr17 be formed, bent or molded?
Blank and lightly bend only in the annealed condition with generous radii; harden 1010–1065 °C, oil or air quench, temper below 200 °C or above 550 °C only with corrosion penalty — avoid 400–550 °C.
7Cr17 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 |
|---|---|---|
| CGB/T 1220 68Cr17 (old 7Cr17) | 0.6 – 0.75 | 0.68 |
| Si | ≤ 1 | 0.4 |
| Mn | ≤ 1 | 0.5 |
| P | ≤ 0.04 | |
| S | ≤ 0.03 | |
| Cr | 16 – 18 | 17 |
| Mooptional residual | ≤ 0.75 | |
| Niresidual | ≤ 0.6 | |
| Fe | balance |
What surface finishes work on 7Cr17?
Grind, belt and mirror-polish after hardening, then passivate (nitric or citric per ASTM A967); PVD/TiN or chrome plating used on budget cutlery for extra corrosion protection.
Surface treatments FabDigit runs on stainless 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).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 7Cr17 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 7Cr17 cost?
7Cr17 is a standard-cost stainless 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.
7Cr17 — frequently asked
What is 7Cr17 used for?
7Cr17 is typically used for kitchen knives, kitchenware, mechanical fittings and shafts. In short: hardenable budget cutlery steel; low-cost 420-type stainless; poor weldability, good hardenability.
What is the yield strength of 7Cr17?
7Cr17 has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 740 MPa (107 ksi) — stronger than 62% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 7Cr17 easy to machine?
Not especially — machinability is rated fair (42/100, better than 79% of stainless steel grades). Machine only in the annealed state with sharp carbide tooling, rigid setups and generous coolant; hardened parts require grinding, EDM or CBN.
Can 7Cr17 be welded?
Not readily — weldability is rated poor (20/100). Poor weldability — 0.7 %C martensitic; if unavoidable preheat 200–300 °C, use 309/410NiMo filler and temper immediately after welding.
What surface finishes work on 7Cr17?
Grind, belt and mirror-polish after hardening, then passivate (nitric or citric per ASTM A967); PVD/TiN or chrome plating used on budget cutlery for extra corrosion protection.
Can 7Cr17 be formed, bent or molded?
Blank and lightly bend only in the annealed condition with generous radii; harden 1010–1065 °C, oil or air quench, temper below 200 °C or above 550 °C only with corrosion penalty — avoid 400–550 °C.
What is the maximum service temperature of 7Cr17?
7Cr17 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 7Cr17-A and 7Cr17 QT-CRYO?
A is the default condition — standard supply condition for machining, blanking and blade grinding before hardening. QT-CRYO: adds a −75 °C sub-zero step to convert retained austenite for maximum hardness and dimensional stability. Yield strength is 415 MPa in A versus 1,700 MPa in QT-CRYO.
How much does 7Cr17 cost?
7Cr17 is a standard-cost stainless 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.
Sources
- GB/T 1220 (68Cr17 / 7Cr17) — SAC (2007)
- GB/T 4232 / ASTM A276 martensitic stainless bar — SAC / ASTM (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels (440A) — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating of Stainless Steels — ASM International (1991)
- ASM Handbook Vol.13B — Corrosion of Stainless Steels — ASM International (2005)
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.