Steel 4028
AISI/SAE 4028 · UNS G40280
4028 is the resulfurized free-machining variant of 4027 molybdenum alloy steel (UNS G40280), combining 0.28 % C and Mo hardenability with sulfide inclusions for chip control (machinability score 72).
Reference datasheet — 4028 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the CD condition
4028 tempers and conditions
4028 is supplied in 10 conditions, soft to hard. CD is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest, most uniform condition — pick it for heavy cold forming, deep drilling/broaching or before final quench-and-temper. | 315 | 500 | 30 | 149 HB | — |
Hot rolled | Lowest-cost mill condition for parts that will be fully machined or subsequently heat treated. | 330 | 550 | 25 | 163 HB | — |
Normalized | Refines grain and homogenizes hot-worked bar or forgings before machining or hardening; better toughness than as-rolled. | 415 | 620 | 25 | 179 HB | — |
Induction hardened | Selective surface hardening of journals and gear teeth; 0.28 % C limits case hardness to about 50 HRC. | 450 | 620 | 10 | 48 HRC | 7.5 % IACS |
Cold drawn, stress relieved | Choose when cold-drawn bar must stay straight after asymmetric machining or hard turning. | 470 | 565 | 18 | 174 HB | 8 % IACS |
quenched and tempered at 650 °C (≈190 HB) | Softest hardened condition — used where machining after heat treatment and maximum ductility are needed. | 490 | 650 | 25 | 192 HB | — |
CDDefault Cold drawn | Standard stock condition for screw-machine work: tight tolerance, bright surface, higher yield and excellent chip control. | 505 | 585 | 16 | 179 HB | — |
quenched and tempered at 540 °C (≈20 HRC) | General-purpose quenched-and-tempered condition with the best toughness-to-strength compromise for this grade. | 570 | 745 | 20 | 19 HRC | — |
quenched and tempered at 425 °C (≈25 HRC) | Balanced strength/ductility for shafts and couplings machined from bar after heat treatment. | 650 | 850 | 16 | 25 HRC | — |
quenched and tempered at 205 °C (≈30 HRC) | Maximum strength/wear condition for small machined parts where impact loading is low. | 745 | 1,000 | 12 | 31 HRC | — |
What is 4028?
4028 is the resulfurized free-machining variant of 4027 molybdenum alloy steel (UNS G40280), combining 0.28 % C and Mo hardenability with sulfide inclusions for chip control (machinability score 72). Default-condition properties are about 505 MPa yield, 585 MPa tensile, 16 % elongation and 179 HB (89 HRB), with a maximum service temperature near 350 °C; forms include hot-rolled, annealed, normalized, cold-drawn and stress-relieved bar, induction-hardened parts and quench-and-temper conditions at 205, 425, 540 and 650 °C. Weldability is poor (score 30) and formability limited (score 40) because sulfur promotes hot cracking and cuts transverse ductility. Choose 4027 when the part must be welded or cold formed. 4028 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). 4028 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 64% of steel grades. Elongation at break is 16% and the elastic modulus is 205 GPa (29.7 Msi).
What is 4028 used for?
- bolts
- fasteners
- machined shafts
Advantages
- Easy to machine — 72/100, better than 97% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
4028 properties
Typical room-temperature values for 4028-CD; bars are the position among steel grades.
Physical3
4028 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).
Mechanical15
4028 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 64% of steel grades. Elongation at break is 16% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4028 is rated for continuous service to 350°C (662 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
4028 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 4028 takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 35%.
Manufacturability8
4028's machinability is very good (72/100, better than 97% of steel grades); weldability poor (30/100); formability fair (40/100).
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. 4028 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4028
Is 4028 easy to machine?
Excellent for a moly alloy steel — MnS inclusions give short chips and ~75 % of AISI 1212; run carbide at 120–200 m/min in the cold-drawn or annealed state, avoid very low feeds that smear the sulfides.
Can 4028 be welded?
Poor: sulfur promotes hot cracking and the 0.28 C + Mo raises hardenability — avoid welding if possible, otherwise preheat 200–260 °C, use low-hydrogen consumables and post-weld temper.
Can 4028 be formed, bent or molded?
Only light cold forming (knurling, thread rolling, mild bending) — sulfide stringers give poor transverse ductility; hot forge 1150–1200 °C, finish above 900 °C, then normalize or anneal.
4028 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 |
|---|---|---|
| Cheat analysis, SAE J404 | 0.25 – 0.3 | 0.28 |
| Mn | 0.7 – 0.9 | 0.8 |
| Si | 0.15 – 0.35 | 0.25 |
| Mo | 0.2 – 0.3 | 0.25 |
| Sintentional resulfurizing addition — the 4027/4028 difference | 0.04 – 0.05 | 0.04 |
| P | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 4028?
No corrosion resistance in bare form: use zinc or zinc-nickel plating, black oxide, manganese phosphate + oil, or QPQ/nitrocarburizing; polishing is limited by sulfide pull-out.
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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 4028 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G40280
How much does 4028 cost?
4028 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.
4028 — frequently asked
What is 4028 used for?
4028 is typically used for bolts, fasteners and machined shafts. In short: free-machining 4027 variant; through-hardenable screw stock; poor welding, high machinability.
What is the yield strength of 4028?
4028 has a typical yield strength of 505 MPa (73.2 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 64% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 4028 easy to machine?
Yes — machinability is rated very good (72/100, better than 97% of steel grades). Excellent for a moly alloy steel — MnS inclusions give short chips and ~75 % of AISI 1212; run carbide at 120–200 m/min in the cold-drawn or annealed state, avoid very low feeds that smear the sulfides.
Can 4028 be welded?
Not readily — weldability is rated poor (30/100). Poor: sulfur promotes hot cracking and the 0.28 C + Mo raises hardenability — avoid welding if possible, otherwise preheat 200–260 °C, use low-hydrogen consumables and post-weld temper.
What surface finishes work on 4028?
No corrosion resistance in bare form: use zinc or zinc-nickel plating, black oxide, manganese phosphate + oil, or QPQ/nitrocarburizing; polishing is limited by sulfide pull-out.
Can 4028 be formed, bent or molded?
Only light cold forming (knurling, thread rolling, mild bending) — sulfide stringers give poor transverse ductility; hot forge 1150–1200 °C, finish above 900 °C, then normalize or anneal.
What is the maximum service temperature of 4028?
4028 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 4028-CD and 4028-QT205?
CD is the default condition — standard stock condition for screw-machine work: tight tolerance, bright surface, higher yield and excellent chip control. QT205: maximum strength/wear condition for small machined parts where impact loading is low. Yield strength is 505 MPa in CD versus 745 MPa in QT205.
How much does 4028 cost?
4028 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.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements — ASTM (2020)
- ASTM A331 — Steel Bars, Alloy, Cold-Finished — ASTM (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating — ASM International (1991)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- SAE J1268 — Hardenability Bands for Carbon and Alloy H Steels — SAE International (2019)
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.