Steel 9CrSi
GB 9CrSi
9CrSi (also written 9SiCr) is a high-carbon low-alloy cold-work tool steel of the GB/T 1299 family, using about 0.9 % C with 1.2–1.6 % Si and 1 % Cr for good hardenability, mild quench distortion and a fine, even carbide distribution; it hardens to 62–64 HRC in oil or slower media.
Values for the Annealed condition
9CrSi tempers and conditions
9CrSi is supplied in 9 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
- Annealed
- Stress Relieved
- Hot Rolled
- Cold Drawn
- Q&T 45-50 HRC
- Q&T 50-55 HRC
- Q&T 56-60 HRC
- Q&T 60-62 HRC
- Hardened 63-65 HRC
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault spheroidize/soft annealed ( , ≤241 HB) | Use the spheroidize-annealed ≤241 HB delivery state at 217 HB for turning, milling, drilling, tapping and forming, then quench and temper to service hardness. | 430 | 750 | 15 | 217 HB | — |
600–700 °C after rough machining | Apply at 600–700 °C after rough machining to relieve stress and limit quench distortion in slender tools and precision dies; at 225 HB it is not a final service condition. | 450 | 770 | 14 | 19 HRC | 7 % IACS |
as-rolled bar/flat, un-annealed | Choose as-rolled bar or flat at 280 HB as the most economical supply form for large sections; spheroidize annealing is normally required before machining. | 570 | 900 | 10 | 29 HRC | 7 % IACS |
annealed then cold drawn/peeled bar | Pick annealed then cold drawn or peeled bar for small-diameter tap and reamer blanks: size accuracy and surface allow direct hardening, but elongation falls to 8%. | 700 | 880 | 8 | 26 HRC | 7 % IACS |
Oil quench + temper 400–500 °C | Choose when toughness governs, as in spring clamps and impact-loaded tooling; tempering at 400–500 °C lowers hardness to about 47 HRC and clearly reduces wear resistance. | 1,350 | 1,550 | 6 | 47 HRC | 6.5 % IACS |
Oil quench + temper 300–400 °C | Pick for cutting edges and die parts under higher impact loads; the 300–400 °C temper trades hardness down to about 53 HRC and 1750 MPa tensile in exchange for toughness. | 1,550 | 1,750 | 3 | 53 HRC | 6.5 % IACS |
Oil quench + temper 200–300 °C | Use for cold stamping dies and thread-rolling plates that must balance toughness and wear; the 200–300 °C temper after oil quench holds about 58 HRC and 2050 MPa tensile. | 1,820 | 2,050 | 1.5 | 58 HRC | 6 % IACS |
Oil quench + temper 160–200 °C | Choose for cutting tools — taps, reamers, dies, shear blades — needing maximum wear resistance; oil quench plus a 160–200 °C temper gives 61 HRC with little toughness reserve. | 2,000 | 2,250 | 1 | 61 HRC | 6 % IACS |
As-quenched | Treat only as an intermediate state straight from the 860–880 °C oil quench; temper immediately to relieve quenching stress, otherwise cracking is likely at 64 HRC. | 2,050 | 2,300 | 0.5 | 64 HRC | 5.7 % IACS |
What is 9CrSi?
9CrSi (also written 9SiCr) is a high-carbon low-alloy cold-work tool steel of the GB/T 1299 family, using about 0.9 % C with 1.2–1.6 % Si and 1 % Cr for good hardenability, mild quench distortion and a fine, even carbide distribution; it hardens to 62–64 HRC in oil or slower media. It is stocked as annealed, hot-rolled and cold-drawn bar for taps, thread dies, reamers, cold blanking dies, shear blades and thread-rolling plates in small to medium sections. The high silicon promotes decarburisation and carbide networks, temper resistance is low with clear softening above 250 °C (max service about 300 °C), and corrosion resistance is poor. Annealed stock is still hard at about 217 HB with only fair machinability. 9CrSi has a density of 7.77 g/cm³ (0.281 lb/in³), lighter than 92% of steel grades. It melts at 1,420°C (2,588 °F). 9CrSi has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 51% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi).
What is 9CrSi used for?
- Taps and thread dies
- Reamers and broaches
- Cold blanking and punching dies
- Shear and guillotine blades
- Thread-rolling plates
- Cold-work punches
- Wear plates and gauges
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Difficult to weld — 15/100, worse than 91% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
9CrSi properties
Typical room-temperature values for 9CrSi-Annealed; bars are the position among steel grades.
Physical3
9CrSi has a density of 7.77 g/cm³ (0.281 lb/in³), lighter than 92% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
9CrSi has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 51% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
9CrSi is rated for continuous service to 300°C (572 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
9CrSi conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of 9CrSi takes about 33 MJ of energy and emits 2.4 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 30%.
Manufacturability8
9CrSi's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (15/100); 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. 9CrSi is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 9CrSi
Is 9CrSi easy to machine?
Machine in the annealed condition (≤241 HB) with coated carbide or high-cobalt HSS; the high silicon makes chips slightly sticky and accelerates tool wear. Once hardened, work only by grinding or EDM.
Can 9CrSi be welded?
High carbon and hardness make it crack-sensitive, so it is normally not welded. For unavoidable repair use matching or martensitic stainless electrodes with 300–400 °C preheat, maintained interpass temperature and an immediate post-weld temper.
Can 9CrSi be formed, bent or molded?
Forge in the 1100–850 °C range, cool slowly and spheroidize-anneal promptly after forging. Cold forming capability is very limited — light straightening and coining only.
Manufacturability
The process limits FabDigit applies to 9CrSi. Every 9CrSi part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better50 / 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 |
9CrSi 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 | 0.85 – 0.95 | 0.9 |
| Siraises hardenability and temper stability; promotes decarburization | 1.2 – 1.6 | 1.4 |
| Mn | 0.3 – 0.6 | 0.45 |
| Cr | 0.95 – 1.25 | 1.1 |
| Pimpurity upper limit | ≤ 0.03 | |
| Simpurity upper limit | ≤ 0.03 | |
| Niresidual element | ≤ 0.25 | |
| Curesidual element | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on 9CrSi?
Grind and polish after quench and temper. Protect with black oxide, phosphating, steam treatment or oil; TiN coating is possible if the coating temperature stays below the tempering temperature.
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
How much does 9CrSi cost?
9CrSi is a premium-cost steel ($$$), pricier than about 57% 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.
9CrSi — frequently asked
What is 9CrSi used for?
9CrSi is typically used for taps and thread dies, reamers and broaches, cold blanking and punching dies, shear and guillotine blades, thread-rolling plates and cold-work punches. In short: cold-work tool steel.
What is the yield strength of 9CrSi?
9CrSi has a typical yield strength of 430 MPa (62.4 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 51% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 9CrSi easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the annealed condition (≤241 HB) with coated carbide or high-cobalt HSS; the high silicon makes chips slightly sticky and accelerates tool wear. Once hardened, work only by grinding or EDM.
Can 9CrSi be welded?
Not readily — weldability is rated poor (15/100). High carbon and hardness make it crack-sensitive, so it is normally not welded. For unavoidable repair use matching or martensitic stainless electrodes with 300–400 °C preheat, maintained interpass temperature and an immediate post-weld temper.
What surface finishes work on 9CrSi?
Grind and polish after quench and temper. Protect with black oxide, phosphating, steam treatment or oil; TiN coating is possible if the coating temperature stays below the tempering temperature.
Can 9CrSi be formed, bent or molded?
Forge in the 1100–850 °C range, cool slowly and spheroidize-anneal promptly after forging. Cold forming capability is very limited — light straightening and coining only.
What is the maximum service temperature of 9CrSi?
9CrSi 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 9CrSi cost?
9CrSi is a premium-cost steel ($$$), pricier than about 57% 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 9CrSi?
Yes — 9CrSi is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys (tool steels) — ASM International (1990)
- 1.2108 / 90CrSi5 cold-work tool steel data (equivalent grade) — European tool-steel producers (2020)
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.