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Steel 5140 · hardness band

Steel 5140 Q&T 48-52HRC

Properties of the Q&T 48-52HRC condition, compared with the other 5140 tempers.

Maximum-hardness condition for small wear parts; brittle, avoid stress raisers and impact.

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What is 5140 Q&T 48-52HRC?

5140 Q&T 48-52HRC is 5140 heat treated to Q&T 48-52HRC — maximum-hardness condition for small wear parts; brittle, avoid stress raisers and impact. 5140 Q&T 48-52HRC has a yield strength of 1,560 MPa (226 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 98% of steel grades. Elongation at break is 9% and the elastic modulus is 210 GPa (30.5 Msi). 5140 Q&T 48-52HRC 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). HR is the default condition FabDigit quotes; Q&T 48-52HRC is available on request or by drawing note.

Advantages

  • High strength — 1,560 MPa (226 ksi), better than 98% of steel grades
  • Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades

Limitations

  • Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
  • Difficult to machine — 22/100, worse than 96% of steel grades
  • Limited ductility — 9%, worse than 93% of steel grades
  • Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades

5140 Q&T 48-52HRC properties

Typical room-temperature values for 5140 Q&T 48-52HRC — 12 properties are specific to this condition; the rest are grade-level values shared by every 5140 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.

Physical3

5140 Q&T 48-52HRC 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).

Density7.85 g/cm³0.28 lb/in³
Melting Point (Solidus)1,420°C2,588 °F
Liquidus Temperature1,490°C2,714 °F

Mechanical16

5140 Q&T 48-52HRC has a yield strength of 1,560 MPa (226 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 98% of steel grades. Elongation at break is 9% and the elastic modulus is 210 GPa (30.5 Msi).

Elastic (Young's) Modulus210 GPa30.5 Msi
Shear Modulus80 GPa11.6 Msi
Bulk Modulus160 GPa23.2 Msi
Poisson's Ratio0.29
Tensile Strength (Ultimate)1,720 MPa249 ksi
Yield Strength (0.2% offset)1,560 MPa226 ksi
Elongation at Break9%
Reduction in Area38%
Compressive Strength450 MPa65.3 ksi
Shear Strength430 MPa62.4 ksi
Fatigue Strength (Endurance Limit)650 MPa94.3 ksi
Fracture Toughness (K_IC)45 MPa·√m41 ksi·√in
Charpy V-Notch Impact (RT)14 J10.3 ft·lbf
Hardness, Brinell480 HB
Hardness, Rockwell B94 HRB
Hardness, Vickers210 HV

Thermal6

5140 Q&T 48-52HRC is rated for continuous service to 180°C (356 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).

Thermal Conductivity44 W/m·K25.4 BTU/hr·ft·°F
Specific Heat Capacity473 J/kg·K0.11 BTU/lb·°F
Thermal Expansion (CTE, 20–100 °C)12.3 µm/m·K6.8 µin/in·°F
Latent Heat of Fusion270 J/g116 BTU/lb
Max Service Temperature (continuous)180°C356 °F
Min Service Temperature-30°C-22 °F

Electrical3

5140 Q&T 48-52HRC conducts electricity at 7.8 % IACS, worse than 58% of steel grades.

Electrical Conductivity7.8 % IACS
Electrical Resistivity2.2×10⁻⁷ Ω·m8.66 µΩ·in
Magnetic Responseferromagnetic

Chemical & Environmental3

Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.

Galvanic Potential (seawater, vs SCE)-0.61 V
Corrosion ResistanceNot recommended12/100
Chemical Resistance SummaryNo inherent corrosion resistance: rusts in humid air, attacked by acids and chlorides; requires oil, phosphate, zinc plating, black oxide or paint. Acceptable in dry oil-lubricated environments.

Sustainability4

Producing a kilogram of 5140 Q&T 48-52HRC takes about 26 MJ of energy and emits 1.9 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 30%.

Embodied Energy (primary production)26 MJ/kg11,178 BTU/lb
Embodied Carbon (primary production)1.9 kg CO₂/kg
Embodied Water60 L/kg7.2 gal/lb
Typical Recycled Content30%

Manufacturability7

5140 Q&T 48-52HRC's machinability is poor (22/100, worse than 96% of steel grades); weldability fair (35/100); formability fair (40/100).

MachinabilityPoor22/100
Machinability Rating (AISI 1212 = 100 %)20%
WeldabilityFair35/100
Formability (cold)Fair40/100
CastabilityPoor30/100
Brazeability / SolderabilityGood55/100
PolishabilityGood60/100

Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.

Other 5140 tempers and conditions

5140 is also supplied in 11 other conditions. The full side-by-side table is on the 5140 overview.

Working with 5140 Q&T 48-52HRC

Is 5140 easy to machine?

Machines well at 180–230 HB (≈65 % of 1212); above 35 HRC use coated carbide, rigid setups and reduced feeds, and prefer rough-machining before final temper.

Can 5140 be welded?

Weldable with care only — preheat 250–350 °C, low-hydrogen consumables, and temper/stress-relieve immediately after welding to avoid martensitic cracking.

Can 5140 be formed, bent or molded?

Hot forge 1100–1200 °C then normalize; cold forming limited to the spheroidize-annealed condition (cold heading of bolts).

What surface finishes work on 5140?

No corrosion resistance — protect by black oxide, phosphate + oil, zinc or chrome plating (bake to relieve hydrogen above 40 HRC); polishes to a fine finish when clean and hardened.

5140 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.

ElementSpec limit (wt %)Nominal
CGB 40Cr: 0.37–0.440.38 – 0.430.4
SiGB 40Cr: 0.17–0.370.15 – 0.350.25
MnGB 40Cr: 0.50–0.800.7 – 0.90.8
CrGB 40Cr / 41Cr4: 0.80–1.100.7 – 0.90.8
P≤ 0.04—
Smax; 0.015–0.035 for resulfurized machining grades≤ 0.04—
Febalance—

5140 Q&T 48-52HRC — frequently asked

What is 5140 Q&T 48-52HRC used for?

5140 Q&T 48-52HRC is typically used for shafts, gears and axles. In short: workhorse chromium spring bar.

What is the yield strength of 5140 Q&T 48-52HRC?

5140 Q&T 48-52HRC has a typical yield strength of 1,560 MPa (226 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 98% of steel grades. Strength varies by condition: see the 12 listed tempers.

Is 5140 Q&T 48-52HRC easy to machine?

Not especially — machinability is rated poor (22/100, worse than 96% of steel grades). Machines well at 180–230 HB (≈65 % of 1212); above 35 HRC use coated carbide, rigid setups and reduced feeds, and prefer rough-machining before final temper.

Can 5140 Q&T 48-52HRC be welded?

With care — weldability is rated fair (35/100). Weldable with care only — preheat 250–350 °C, low-hydrogen consumables, and temper/stress-relieve immediately after welding to avoid martensitic cracking.

What surface finishes work on 5140 Q&T 48-52HRC?

No corrosion resistance — protect by black oxide, phosphate + oil, zinc or chrome plating (bake to relieve hydrogen above 40 HRC); polishes to a fine finish when clean and hardened.

Can 5140 Q&T 48-52HRC be formed, bent or molded?

Hot forge 1100–1200 °C then normalize; cold forming limited to the spheroidize-annealed condition (cold heading of bolts).

What is the maximum service temperature of 5140 Q&T 48-52HRC?

5140 Q&T 48-52HRC is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.

What is the difference between 5140-HR and 5140-IH?

HR is the default condition — cheapest stock condition for parts that will be heat treated after rough machining. IH: select for shaft journals, splines and gear teeth needing a hard wear surface with a tough core. Yield strength is 440 MPa in HR versus 860 MPa in IH.

Can FabDigit make parts in 5140 Q&T 48-52HRC?

Yes — 5140 Q&T 48-52HRC is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.

Sources

  1. SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
  2. GB/T 3077 — Alloy Structure Steels (40Cr) — SAC (2015)
  3. EN 10083-3 — Quenched and tempered steels, 41Cr4 (1.7035) — CEN (2006)
  4. JIS G 4053 — Low-alloyed structural steels (SCr440) — JSA (2016)
  5. ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
  6. ASM Handbook Vol.4 — Heat Treating — ASM International (1991)
  7. ASM Handbook Vol.16 — Machining — ASM International (1989)
  8. Mysteel / SMM 40Cr (2026)

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.