Steel SUM23 · temper
Steel SUM23 Annealed
Properties of the Annealed condition, compared with the other SUM23 tempers.
Softest condition; chosen when heavy cold heading, deep bending or stress-free machining is required.
What is SUM23 Annealed?
SUM23 Annealed is SUM23 in the Annealed temper — softest condition; chosen when heavy cold heading, deep bending or stress-free machining is required. SUM23 Annealed has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 380 MPa (55.1 ksi) — weaker than 97% of steel grades. Elongation at break is 28% and the elastic modulus is 200 GPa (29 Msi). SUM23 Annealed has a density of 7.87 g/cm³ (0.284 lb/in³), heavier than 91% of steel grades. It melts at 1,420°C (2,588 °F). HR is the default condition FabDigit quotes; Annealed is available on request or by drawing note.
Advantages
- Easy to machine — 88/100, better than 99% of steel grades
- High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
- 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
- Ductile — tolerates forming and impact — 28%, better than 88% of steel grades
Limitations
- Low strength — 230 MPa (33.4 ksi), worse than 97% of steel grades
- Hard to polish — 40/100, worse than 96% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
SUM23 Annealed properties
Typical room-temperature values for SUM23 Annealed — 11 properties are specific to this condition; the rest are grade-level values shared by every SUM23 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
SUM23 Annealed has a density of 7.87 g/cm³ (0.284 lb/in³), heavier than 91% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical13
SUM23 Annealed has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 380 MPa (55.1 ksi) — weaker than 97% of steel grades. Elongation at break is 28% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
SUM23 Annealed is rated for continuous service to 400°C (752 °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
SUM23 Annealed conducts electricity at 10.8 % IACS, better than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (8/100), worse than 99% of steel grades.
Sustainability4
Producing a kilogram of SUM23 Annealed takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 40%.
Manufacturability7
SUM23 Annealed's machinability is excellent (88/100, better than 99% of steel grades); weldability poor (20/100); formability good (65/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other SUM23 tempers and conditions
SUM23 is also supplied in 4 other conditions. The full side-by-side table is on the SUM23 overview.
- HRDefaultCheapest mill form for large sections or for re-drawing/forging; loose tolerance and scaled surface.250 MPa yield · 121 HB
- CDDefault stock form for screw-machine work: best size tolerance, straightness and chip control.415 MPa yield · 167 HB
- CRFlat product with tight thickness and bright surface for stamped-then-machined parts.380 MPa yield · 152 HB
- AnnealedSoftest condition; chosen when heavy cold heading, deep bending or stress-free machining is required.230 MPa yield · 111 HB
Working with SUM23 Annealed
Is SUM23 easy to machine?
Benchmark free-cutting steel: run high SFM with light feeds on Swiss/CNC lathes, short broken chips, excellent tool life and finish; avoid grinding-heavy operations where sulfide pull-out hurts Ra.
Can SUM23 be welded?
Not recommended for structural welds — high S and P cause hot cracking and porosity; if unavoidable, use low-hydrogen filler, preheat and expect reduced joint properties.
Can SUM23 be formed, bent or molded?
Cold heading and light bending are possible in the annealed condition, but transverse ductility is poor because of sulfide stringers — bend across the rolling direction with generous radii.
What surface finishes work on SUM23?
No anodizing; protect with zinc or zinc-nickel electroplate, black oxide, phosphate + oil, or nitrocarburizing; case carbonitriding is used for wear surfaces on low-carbon SUM23.
SUM23 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 |
|---|---|---|
| CJIS G4804 SUM23 | ≤ 0.09 | 0.07 |
| Mn | 0.75 – 1.05 | 0.9 |
| Prephosphorized for chip breaking | 0.04 – 0.09 | 0.06 |
| SMnS inclusions give free-cutting behaviour | 0.26 – 0.35 | 0.3 |
| Sinot specified in JIS; kept low (rimmed/capped practice) | ≤ 0.05 | 0.02 |
| Curesidual limit, typical mill practice | ≤ 0.25 | — |
| Fe | balance | — |
SUM23 Annealed — frequently asked
What is SUM23 Annealed used for?
SUM23 Annealed is typically used for screw machine parts, fasteners and threaded studs, bushings and spacers, hydraulic and pneumatic fittings, light-duty shafts and pins and connector bodies. In short: free-machining Japanese bar.
What is the yield strength of SUM23 Annealed?
SUM23 Annealed has a typical yield strength of 230 MPa (33.4 ksi) and a tensile strength of 380 MPa (55.1 ksi) — weaker than 97% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is SUM23 Annealed easy to machine?
Yes — machinability is rated excellent (88/100, better than 99% of steel grades). Benchmark free-cutting steel: run high SFM with light feeds on Swiss/CNC lathes, short broken chips, excellent tool life and finish; avoid grinding-heavy operations where sulfide pull-out hurts Ra.
Can SUM23 Annealed be welded?
Not readily — weldability is rated poor (20/100). Not recommended for structural welds — high S and P cause hot cracking and porosity; if unavoidable, use low-hydrogen filler, preheat and expect reduced joint properties.
What surface finishes work on SUM23 Annealed?
No anodizing; protect with zinc or zinc-nickel electroplate, black oxide, phosphate + oil, or nitrocarburizing; case carbonitriding is used for wear surfaces on low-carbon SUM23.
Can SUM23 Annealed be formed, bent or molded?
Cold heading and light bending are possible in the annealed condition, but transverse ductility is poor because of sulfide stringers — bend across the rolling direction with generous radii.
What is the maximum service temperature of SUM23 Annealed?
SUM23 Annealed 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 SUM23-HR and SUM23-CD?
HR is the default condition — cheapest mill form for large sections or for re-drawing/forging; loose tolerance and scaled surface. CD: default stock form for screw-machine work: best size tolerance, straightness and chip control. Yield strength is 250 MPa in HR versus 415 MPa in CD.
Can FabDigit make parts in SUM23 Annealed?
Yes — SUM23 Annealed is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- JIS G 4804 — Sulfur and sulfur-composite free-cutting steels — JSA (2019)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — 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.