Steel SUM23
JIS SUM23
SUM23 is a resulfurized, rephosphorized low-carbon free-cutting steel to the JIS bar standard, closely equivalent to AISI 1215, in which sulfide inclusions break chips and reduce cutting loads.
Values for the HR condition
SUM23 tempers and conditions
SUM23 is supplied in 4 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
subcritical / spheroidize annealed | Softest condition; chosen when heavy cold heading, deep bending or stress-free machining is required. | 230 | 380 | 28 | 111 HB | — |
HRDefault Hot rolled | Cheapest mill form for large sections or for re-drawing/forging; loose tolerance and scaled surface. | 250 | 415 | 22 | 121 HB | — |
Cold rolled | Flat product with tight thickness and bright surface for stamped-then-machined parts. | 380 | 500 | 12 | 152 HB | 10.8 % IACS |
Cold drawn | Default stock form for screw-machine work: best size tolerance, straightness and chip control. | 415 | 540 | 10 | 167 HB | — |
Supply forms, finishes and certifications
Ways SUM23 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
TGP | Turned, ground and polished bar | Surface finish |
What is SUM23?
SUM23 is a resulfurized, rephosphorized low-carbon free-cutting steel to the JIS bar standard, closely equivalent to AISI 1215, in which sulfide inclusions break chips and reduce cutting loads. It is the default bar stock for high-volume screw-machine work, supplied HR, CR, cold-drawn, annealed and TGP; the default condition gives 250 MPa yield, 415 MPa tensile, 22% elongation, 121 HB (68 HRB) and a machinability score of 90. Strength is low, the sulfur and phosphorus make it unsuitable for structural welding, transverse ductility is poor and corrosion resistance is nil — plate or oil the parts, or move to 1144 when higher strength is needed. SUM23 has a density of 7.87 g/cm³ (0.284 lb/in³), heavier than 92% of steel grades. It melts at 1,420°C (2,588 °F). SUM23 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 94% of steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi).
What is SUM23 used for?
- Screw machine parts
- Fasteners and threaded studs
- Bushings and spacers
- Hydraulic and pneumatic fittings
- Light-duty shafts and pins
- Connector bodies
- Appliance and instrument hardware
Advantages
- Easy to machine — 90/100, 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
Limitations
- Hard to polish — 40/100, worse than 96% of steel grades
- Low strength — 250 MPa (36.3 ksi), worse than 94% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
SUM23 properties
Typical room-temperature values for SUM23-HR; bars are the position among steel grades.
Physical3
SUM23 has a density of 7.87 g/cm³ (0.284 lb/in³), heavier than 92% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical13
SUM23 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 94% of steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
SUM23 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 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 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's machinability is excellent (90/100, better than 99% of steel grades); weldability poor (20/100); formability good (55/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. SUM23 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SUM23
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.
Manufacturability
The process limits FabDigit applies to SUM23. Every SUM23 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Excellent90 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
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 |
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.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel SUM23 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 1215
How much does SUM23 cost?
SUM23 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
SUM23 — frequently asked
What is SUM23 used for?
SUM23 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?
SUM23 has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 94% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is SUM23 easy to machine?
Yes — machinability is rated excellent (90/100, 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 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?
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 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?
SUM23 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.
How much does SUM23 cost?
SUM23 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in SUM23?
Yes — SUM23 is available for CNC machining; every part is priced by an engineer rather than instantly. 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.