Stainless Steel 420HC-QT50
Hardness band
AISI/SAE 420HC
QT50 = hardened and tempered to 48–51 HRC
Balanced condition for scissors, shears, surgical and dental instruments needing some toughness with decent wear resistance.
Values for the QT50 condition
Other 420HC tempers and conditions
420HC is listed in 8 conditions; see the grade overview at 420HC.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard stocked condition for bar, plate and strip that will be blanked, machined or ground and then hardened by the user. | 345 | 660 | 22 | 195 HB | — |
Cold rolled and annealed strip/coil | Pick for stamped or laser-cut blade and cutlery blanks where flat, clean, dimensionally tight soft strip is needed. | 380 | 690 | 20 | 15 HRC | 3.1 % IACS |
Cold drawn | Choose for as-supplied strength and straightness in machined shafts, pins and screw-machine parts that may not be hardened. | 620 | 790 | 12 | 235 HB | — |
Hardened and tempered to 42–46 HRC | Use where shock loading or bending matters more than edge holding — machetes, large tools, valve and pump parts; note the higher temper reduces corrosion resistance. | 1,200 | 1,450 | 8 | 44 HRC | — |
QT50This page Hardened and tempered to 48–51 HRC | Balanced condition for scissors, shears, surgical and dental instruments needing some toughness with decent wear resistance. | 1,400 | 1,700 | 5 | 50 HRC | — |
Hardened and low-temperature tempered to 52–55 HRC | Common production knife hardness — good edge retention with enough toughness for folding and kitchen blades. | 1,520 | 1,860 | 3 | 54 HRC | — |
Hardened and tempered to maximum hardness 56–58 HRC | Maximum edge retention and wear resistance for premium 420HC blades and wear parts; accept low toughness and grinding-only machining. | 1,650 | 1,980 | 2 | 57 HRC | — |
Stress relieved | Knife-industry route: quench, sub-zero soak to convert retained austenite, then low temper — slightly higher and more uniform hardness with better dimensional stability than plain Q&T. | 1,650 | 2,020 | 2 | 58 HRC | 2.9 % IACS |
What is 420HC-QT50?
420HC-QT50 is 420HC heat treated to QT50 — balanced condition for scissors, shears, surgical and dental instruments needing some toughness with decent wear resistance. 420HC-QT50 has a yield strength of 1,400 MPa (203 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 99% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 200 GPa (29 Msi). 420HC-QT50 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,450°C (2,642 °F). A is the default condition FabDigit quotes; QT50 is available on request or by drawing note.
Advantages
- High strength — 1,400 MPa (203 ksi), better than 99% of stainless steel grades
- High electrical conductivity — 3.1 % IACS, better than 99% of stainless steel grades
- Low embodied carbon — 3 kg CO₂/kg, better than 97% of stainless steel grades
- Conducts heat well — 24.9 W/m·K (14.4 BTU/hr·ft·°F), better than 87% of stainless steel grades
Limitations
- Limited ductility — 5%, worse than 100% of stainless steel grades
- Difficult to machine — 15/100, worse than 100% of stainless steel grades
- Limited formability — 5/100, worse than 99% of stainless steel grades
- Limited service temperature — 300°C (572 °F), worse than 90% of stainless steel grades
- Difficult to weld — 30/100, worse than 88% of stainless steel grades
420HC-QT50 properties
Typical room-temperature values for 420HC-QT50; 16 are specific to this condition. Other listed values are 420HC reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
420HC-QT50 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,450°C (2,642 °F).
Mechanical14
420HC-QT50 has a yield strength of 1,400 MPa (203 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 99% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
420HC-QT50 is rated for continuous service to 300°C (572 °F). It conducts heat at 24.9 W/m·K (14.4 BTU/hr·ft·°F), better than 87% of stainless steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
420HC-QT50 conducts electricity at 3.1 % IACS, better than 99% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 85% of stainless steel grades.
Sustainability4
Producing a kilogram of 420HC-QT50 takes about 46 MJ of energy and emits 3 kg of CO₂ — less than 88% of stainless steel grades. Typical recycled content is 45%.
Manufacturability6
420HC-QT50's machinability is poor (15/100, worse than 100% of stainless steel grades); weldability poor (30/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 420HC-QT50
Is 420HC easy to machine?
Machine only in the annealed state with sharp, rigid, positive-rake carbide tooling and flood coolant (≈45 % of 1212); hardened 420HC above ~45 HRC is effectively a grinding/EDM job.
Can 420HC be welded?
Poor weldability — air-hardening HAZ cracks readily; if unavoidable, preheat 200–300 °C, use 410/309L filler and temper or fully re-anneal afterwards.
Can 420HC be formed, bent or molded?
Blank, bend and coin in the soft annealed strip condition with generous radii; harden after forming, and expect ~0.05–0.15 % dimensional growth plus warping during quench.
What surface finishes work on 420HC?
Grinds and mirror-polishes very well when hardened; always passivate (nitric/citric) after grinding, and avoid tempering above ~400 °C or chloride-bearing pickles which drop corrosion resistance.
420HC 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 |
|---|---|---|
| Chigh-carbon variant of S42000 (base 420 is ≥0.15 C) | 0.4 – 0.5 | 0.45 |
| Cr | 12 – 14 | 13 |
| Mn | ≤ 1 | 0.4 |
| Si | ≤ 1 | 0.4 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Niresidual/optional, mill practice | ≤ 0.75 | 0.25 |
| Mooptional residual in some producer variants | ≤ 0.5 | — |
| Voptional grain refiner in some 420HC melts | ≤ 0.3 | — |
| Fe | balance | — |
420HC-QT50 — frequently asked
What is 420HC-QT50 used for?
420HC-QT50 is typically used for pocket knives, fixed-blade knives and cutlery. In short: harder than standard 420; low-cost stainless blade steel; form soft, harden after.
What is the yield strength of 420HC-QT50?
420HC-QT50 has a typical yield strength of 1,400 MPa (203 ksi) and a tensile strength of 1,700 MPa (247 ksi) — stronger than 99% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.
Is 420HC-QT50 easy to machine?
Not especially — machinability is rated poor (15/100, worse than 100% of stainless steel grades). Machine only in the annealed state with sharp, rigid, positive-rake carbide tooling and flood coolant (≈45 % of 1212); hardened 420HC above ~45 HRC is effectively a grinding/EDM job.
Can 420HC-QT50 be welded?
Not readily — weldability is rated poor (30/100). Poor weldability — air-hardening HAZ cracks readily; if unavoidable, preheat 200–300 °C, use 410/309L filler and temper or fully re-anneal afterwards.
What surface finishes work on 420HC-QT50?
Grinds and mirror-polishes very well when hardened; always passivate (nitric/citric) after grinding, and avoid tempering above ~400 °C or chloride-bearing pickles which drop corrosion resistance.
Can 420HC-QT50 be formed, bent or molded?
Blank, bend and coin in the soft annealed strip condition with generous radii; harden after forming, and expect ~0.05–0.15 % dimensional growth plus warping during quench.
What is the maximum service temperature of 420HC-QT50?
420HC-QT50 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.
What is the difference between 420HC-A and 420HC-QT58?
A is the default condition — standard stocked condition for bar, plate and strip that will be blanked, machined or ground and then hardened by the user. QT58: maximum edge retention and wear resistance for premium 420HC blades and wear parts; accept low toughness and grinding-only machining. Yield strength is 345 MPa in A versus 1,650 MPa in QT58.
Sources
- ASTM A276/A276M — Stainless Steel Bars and Shapes — ASTM International (2023)
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip — ASTM International (2023)
- GB/T 1220 / GB/T 3280 (4Cr13 / 20Cr13-40Cr13 series) (2016)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- 420HC / 420 modified cutlery steel datasheets (Crucible/Latrobe, Sandvik, Aperam class data) — various mills (2022)
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.