Steel 10B38 · hardness band
Steel 10B38 Q&T 25-32 HRC
Properties of the Q&T 25-32 HRC condition, compared with the other 10B38 tempers.
Standard bolt condition: oil/water quench plus high temper, giving 800–830 MPa class strength with good ductility.
What is 10B38 Q&T 25-32 HRC?
10B38 Q&T 25-32 HRC is 10B38 heat treated to Q&T 25-32 HRC — standard bolt condition: oil/water quench plus high temper, giving 800–830 MPa class strength with good ductility. 10B38 Q&T 25-32 HRC has a yield strength of 740 MPa (107 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 83% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi). 10B38 Q&T 25-32 HRC 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 25-32 HRC is available on request or by drawing note.
Advantages
- High strength — 740 MPa (107 ksi), better than 83% of steel grades
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- High electrical conductivity — 10 % IACS, better than 82% of steel grades
10B38 Q&T 25-32 HRC properties
Typical room-temperature values for 10B38 Q&T 25-32 HRC — 10 properties are specific to this condition; the rest are grade-level values shared by every 10B38 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
10B38 Q&T 25-32 HRC 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).
Mechanical13
10B38 Q&T 25-32 HRC has a yield strength of 740 MPa (107 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 83% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
10B38 Q&T 25-32 HRC is rated for continuous service to 400°C (752 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
10B38 Q&T 25-32 HRC conducts electricity at 10 % IACS, better than 82% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 87% of steel grades.
Sustainability4
Producing a kilogram of 10B38 Q&T 25-32 HRC takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
10B38 Q&T 25-32 HRC's machinability is good (58/100, better than 75% of steel grades); weldability good (55/100); 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 10B38 tempers and conditions
10B38 is also supplied in 7 other conditions. The full side-by-side table is on the 10B38 overview.
- HRDefaultDefault stock form for wire rod and bar destined for cold heading or subsequent Q&T.320 MPa yield · 163 HB
- Q&T 40-45 HRCFor wear-loaded pins, plough shares and studs where hardness matters more than toughness.1,180 MPa yield · 43 HRC
- Q&T 32-38 HRCHigher-strength fastener condition (~1040 MPa class); watch for hydrogen embrittlement risk after plating.960 MPa yield · 35 HRC
- Q&T 25-32 HRCStandard bolt condition: oil/water quench plus high temper, giving 800–830 MPa class strength with good ductility.740 MPa yield · 29 HRC
- CRPick for close tolerance, smooth surface and higher as-supplied strength when no further heat treatment is planned.540 MPa yield · 190 HB
- NormalizedUniform fine-grain structure and predictable response to later quenching; used to reset banded hot-rolled structure.335 MPa yield · 163 HB
- AnnealedSoftest condition, for maximum cold formability and machining of complex shapes before hardening.285 MPa yield · 149 HB
- SA-CHQSpheroidized wire for severe cold heading of bolt blanks; the normal starting condition for 8.8/10.9 fastener production.270 MPa yield · 140 HB
Working with 10B38 Q&T 25-32 HRC
Is 10B38 easy to machine?
Machines like 1038 (≈60% of 1212); best in normalized or Q&T-to-~30 HRC condition, use rigid setups and carbide at moderate speed — boron slightly raises tool wear.
Can 10B38 be welded?
Weldable by SMAW/GMAW/resistance methods but 0.39% C plus boron gives high hardenability: preheat 150–250 °C, low-hydrogen consumables and post-weld temper to avoid HAZ cracking.
Can 10B38 be formed, bent or molded?
In spheroidize-annealed CHQ wire it cold-heads and thread-rolls readily; hot forge 1100–1250 °C, then normalize before quench-hardening for consistent boron effect.
What surface finishes work on 10B38?
No inherent corrosion resistance — use zinc or zinc-nickel electroplate (bake to relieve hydrogen at >32 HRC), hot-dip galvanizing, phosphate+oil, or zinc-flake coatings; polishes to a fair finish only.
10B38 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 |
|---|---|---|
| CSAE J403 10B38 | 0.35 – 0.43 | 0.39 |
| Mn | 0.6 – 0.9 | 0.75 |
| Sibar/rod; may be 0.10 min for CHQ wire | 0.15 – 0.35 | 0.25 |
| Bboron addition for hardenability | 5×10⁻⁴ – 0 | 0 |
| P | ≤ 0.03 | — |
| Smax (0.050 in some bar specs) | ≤ 0.04 | — |
| Fe | balance | — |
10B38 Q&T 25-32 HRC — frequently asked
What is 10B38 Q&T 25-32 HRC used for?
10B38 Q&T 25-32 HRC is typically used for fasteners, bolts and threaded studs. In short: boron cold-heading wire.
What is the yield strength of 10B38 Q&T 25-32 HRC?
10B38 Q&T 25-32 HRC has a typical yield strength of 740 MPa (107 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 83% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 10B38 Q&T 25-32 HRC easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like 1038 (≈60% of 1212); best in normalized or Q&T-to-~30 HRC condition, use rigid setups and carbide at moderate speed — boron slightly raises tool wear.
Can 10B38 Q&T 25-32 HRC be welded?
Yes — weldability is rated good (55/100). Weldable by SMAW/GMAW/resistance methods but 0.39% C plus boron gives high hardenability: preheat 150–250 °C, low-hydrogen consumables and post-weld temper to avoid HAZ cracking.
What surface finishes work on 10B38 Q&T 25-32 HRC?
No inherent corrosion resistance — use zinc or zinc-nickel electroplate (bake to relieve hydrogen at >32 HRC), hot-dip galvanizing, phosphate+oil, or zinc-flake coatings; polishes to a fair finish only.
Can 10B38 Q&T 25-32 HRC be formed, bent or molded?
In spheroidize-annealed CHQ wire it cold-heads and thread-rolls readily; hot forge 1100–1250 °C, then normalize before quench-hardening for consistent boron effect.
What is the maximum service temperature of 10B38 Q&T 25-32 HRC?
10B38 Q&T 25-32 HRC is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 10B38-HR and 10B38-CR?
HR is the default condition — default stock form for wire rod and bar destined for cold heading or subsequent Q&T. CR: pick for close tolerance, smooth surface and higher as-supplied strength when no further heat treatment is planned. Yield strength is 320 MPa in HR versus 540 MPa in CR.
Can FabDigit make parts in 10B38 Q&T 25-32 HRC?
Yes — 10B38 Q&T 25-32 HRC 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
- SAE J403 — Chemical Compositions of SAE Carbon Steels — SAE International (2014)
- SAE J404 / J1268 — Hardenability of boron-treated carbon steels — SAE International (2013)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements — ASTM (2020)
- ISO 898-1 — Mechanical properties of fasteners, property classes 8.8/10.9 — ISO (2013)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
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.