Steel 1108 CARB-QT
Heat-treated state
AISI/SAE 1108 · UNS G11080
CARB-QT = carburized, Quenched & Tempered
Use when a wear-resistant 58–62 HRC case over a tough low-carbon core is needed on a machined part.
Values for the CARB-QT condition
Other 1108 tempers and conditions
1108 is listed in 6 conditions; see the grade overview at 1108.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition; used before heavy cold heading, deep bending or as a pre-carburizing state. | 180 | 325 | 33 | 90 HB | 10.8 % IACS |
Hot rolled | Lowest-cost form for parts that will be fully machined or subsequently cold worked/carburized. | 190 | 340 | 30 | 95 HB | — |
Normalized | Uniform fine grain and predictable machining response after hot forging. | 215 | 360 | 30 | 100 HB | 10.5 % IACS |
Cold Drawn, Stress Relieved | Pick when machining removes material asymmetrically and residual-stress distortion must be minimised. | 300 | 370 | 22 | 105 HB | 10.5 % IACS |
CDDefault Cold drawn | Standard screw-machine stock: close size tolerance, bright finish, higher strength and the best chip control. | 330 | 385 | 20 | 111 HB | — |
CARB-QTThis page Carburized, Quenched & Tempered | Use when a wear-resistant 58–62 HRC case over a tough low-carbon core is needed on a machined part. | 415 | 620 | 15 | 60 HRC | — |
What is 1108 CARB-QT?
1108 CARB-QT is 1108 heat treated to CARB-QT — use when a wear-resistant 58–62 HRC case over a tough low-carbon core is needed on a machined part. 1108 CARB-QT has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 56% of steel grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi). 1108 CARB-QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). CD is the default condition FabDigit quotes; CARB-QT is available on request or by drawing note.
Advantages
- Conducts heat well — 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High electrical conductivity — 10.5 % IACS, better than 89% of steel grades
Limitations
- Limited formability — 5/100, worse than 99% of steel grades
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Difficult to machine — 20/100, worse than 97% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
1108 CARB-QT properties
Typical room-temperature values for 1108 CARB-QT; 13 are specific to this condition. Other listed values are 1108 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
1108 CARB-QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical14
1108 CARB-QT has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 56% of steel grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
1108 CARB-QT is rated for continuous service to 180°C (356 °F). It conducts heat at 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
1108 CARB-QT conducts electricity at 10.5 % IACS, better than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (8/100), worse than 99% of steel grades.
Sustainability4
Producing a kilogram of 1108 CARB-QT takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
1108 CARB-QT's machinability is poor (20/100, worse than 97% of steel grades); weldability poor (20/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1108 CARB-QT
Is 1108 easy to machine?
Excellent high-speed screw-machine steel — MnS gives short chips and good tool life; ~80 % of 1212, but keep speeds high to avoid a gummy built-up edge at low carbon.
Can 1108 be welded?
Weldable by resistance and short-arc processes with low heat input, but the 0.08–0.13 % S promotes hot/solidification cracking and porosity — avoid structural welding or use low-hydrogen filler and preheat.
Can 1108 be formed, bent or molded?
Good cold heading and bending in the longitudinal direction; sulfide stringers cause splitting in tight transverse bends, so anneal and use generous bend radii.
What surface finishes work on 1108?
No corrosion resistance bare — specify oil, phosphate, black oxide, zinc or nickel plating; sulfide inclusions can leave pinholes in bright plating and streaks in polished surfaces.
1108 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 | 0.08 – 0.13 | 0.1 |
| Mn | 0.5 – 0.8 | 0.65 |
| P | ≤ 0.04 | 0.02 |
| Sresulfurized for machinability | 0.08 – 0.13 | 0.1 |
| Fe | balance | — |
1108 CARB-QT — frequently asked
What is 1108 CARB-QT used for?
1108 CARB-QT is typically used for small fasteners, screw machine parts, light shafts and pins. In short: light-duty free-machining steel; about 80 % of 1212; low-carbon screw-machine grade.
What is the yield strength of 1108 CARB-QT?
1108 CARB-QT has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 56% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 1108 CARB-QT easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of steel grades). Excellent high-speed screw-machine steel — MnS gives short chips and good tool life; ~80 % of 1212, but keep speeds high to avoid a gummy built-up edge at low carbon.
Can 1108 CARB-QT be welded?
Not readily — weldability is rated poor (20/100). Weldable by resistance and short-arc processes with low heat input, but the 0.08–0.13 % S promotes hot/solidification cracking and porosity — avoid structural welding or use low-hydrogen filler and preheat.
What surface finishes work on 1108 CARB-QT?
No corrosion resistance bare — specify oil, phosphate, black oxide, zinc or nickel plating; sulfide inclusions can leave pinholes in bright plating and streaks in polished surfaces.
Can 1108 CARB-QT be formed, bent or molded?
Good cold heading and bending in the longitudinal direction; sulfide stringers cause splitting in tight transverse bends, so anneal and use generous bend radii.
What is the maximum service temperature of 1108 CARB-QT?
1108 CARB-QT 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 1108-CD and 1108-A?
CD is the default condition — standard screw-machine stock: close size tolerance, bright finish, higher strength and the best chip control. A: softest condition; used before heavy cold heading, deep bending or as a pre-carburizing state. Yield strength is 330 MPa in CD versus 180 MPa in A.
Sources
- SAE J403 — Chemical Compositions of SAE Carbon Steels — SAE International (2014)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements — ASTM (2020)
- ASTM A108 — Steel Bar, Carbon and Alloy, Cold-Finished — ASTM (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- SAE J1397 — Estimated Mechanical Properties and Machinability of Steel Bars — SAE International (2009)
- GB/T 8731 (comparable Y08/Y12 grades) (2008)
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.