Steel 9CrSi · hardness band
Steel 9CrSi Q&T 45-50 HRC
Properties of the Q&T 45-50 HRC condition, compared with the other 9CrSi tempers.
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.
What is 9CrSi Q&T 45-50 HRC?
9CrSi Q&T 45-50 HRC is 9CrSi heat treated to Q&T 45-50 HRC — 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. 9CrSi Q&T 45-50 HRC has a yield strength of 1,350 MPa (196 ksi) and a tensile strength of 1,550 MPa (225 ksi) — stronger than 95% of steel grades. Elongation at break is 6% and the elastic modulus is 210 GPa (30.5 Msi). 9CrSi Q&T 45-50 HRC 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). Annealed is the default condition FabDigit quotes; Q&T 45-50 HRC is available on request or by drawing note.
Advantages
- High strength — 1,350 MPa (196 ksi), better than 95% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Limited ductility — 6%, worse than 98% of steel grades
- Difficult to machine — 18/100, worse than 98% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
9CrSi Q&T 45-50 HRC properties
Typical room-temperature values for 9CrSi Q&T 45-50 HRC — 9 properties are specific to this condition; the rest are grade-level values shared by every 9CrSi temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
9CrSi Q&T 45-50 HRC 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 Q&T 45-50 HRC has a yield strength of 1,350 MPa (196 ksi) and a tensile strength of 1,550 MPa (225 ksi) — stronger than 95% of steel grades. Elongation at break is 6% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
9CrSi Q&T 45-50 HRC is rated for continuous service to 350°C (662 °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 Q&T 45-50 HRC 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 Q&T 45-50 HRC 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 Q&T 45-50 HRC's machinability is poor (18/100, worse than 98% of steel grades); weldability poor (15/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 9CrSi tempers and conditions
9CrSi is also supplied in 8 other conditions. The full side-by-side table is on the 9CrSi overview.
- AnnealedDefaultUse 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 MPa yield · 217 HB
- Q&T 60-62 HRCChoose 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.2,250 MPa tensile
- Q&T 56-60 HRCUse 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.2,050 MPa tensile
- Q&T 50-55 HRCPick 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 MPa yield · 53 HRC
- Q&T 45-50 HRCChoose 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 MPa yield · 47 HRC
Working with 9CrSi Q&T 45-50 HRC
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.
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.
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 | — |
9CrSi Q&T 45-50 HRC — frequently asked
What is 9CrSi Q&T 45-50 HRC used for?
9CrSi Q&T 45-50 HRC 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 Q&T 45-50 HRC?
9CrSi Q&T 45-50 HRC has a typical yield strength of 1,350 MPa (196 ksi) and a tensile strength of 1,550 MPa (225 ksi) — stronger than 95% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 9CrSi Q&T 45-50 HRC easy to machine?
Not especially — machinability is rated poor (18/100, worse than 98% 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 Q&T 45-50 HRC 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 Q&T 45-50 HRC?
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 Q&T 45-50 HRC 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 Q&T 45-50 HRC?
9CrSi Q&T 45-50 HRC is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 9CrSi Q&T 45-50 HRC?
Yes — 9CrSi Q&T 45-50 HRC is available for CNC machining with instant online pricing. 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.