Steel 10B38 · supply condition · default condition
Steel 10B38-HR
Properties of the HR condition, compared with the other 10B38 tempers.
Default stock form for wire rod and bar destined for cold heading or subsequent Q&T.
What is 10B38-HR?
10B38-HR is 10B38 supplied in the HR condition — default stock form for wire rod and bar destined for cold heading or subsequent Q&T. 10B38-HR has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 80% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi). 10B38-HR 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).
Advantages
- 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
Limitations
- Low strength — 320 MPa (46.4 ksi), worse than 80% of steel grades
10B38-HR properties
Typical room-temperature values for 10B38-HR — 9 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-HR 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-HR has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 80% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
10B38-HR 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-HR 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-HR 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-HR's machinability is good (58/100, better than 75% of steel grades); weldability good (55/100); formability good (60/100).
Common Calculations5
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-HR
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-HR — frequently asked
What is 10B38-HR used for?
10B38-HR is typically used for fasteners, bolts and threaded studs. In short: boron cold-heading wire.
What is the yield strength of 10B38-HR?
10B38-HR has a typical yield strength of 320 MPa (46.4 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 80% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 10B38-HR 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-HR 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-HR?
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-HR 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-HR?
10B38-HR 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-HR?
Yes — 10B38-HR 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.