Steel SCM432
JIS SCM432 · AISI/SAE 4137
SCM432 is a medium-carbon through-hardening chromium-molybdenum steel in the JIS SCM family, equivalent to AISI 4137, sitting between SCM430 and SCM435 in carbon and strength.
Reference datasheet — SCM432 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 QT condition
SCM432 tempers and conditions
SCM432 is supplied in 9 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full/spheroidize annealed bar | Softest condition for deep machining, cold forming or before final heat treatment. | 400 | 620 | 24 | 187 HB | — |
Hot rolled | Cheapest mill condition, bought as feedstock for forging and subsequent heat treatment. | 430 | 700 | 20 | 14 HRC | 8.2 % IACS |
Normalized | Uniform fine-grain structure for forgings before machining or as a moderate-strength delivery condition. | 470 | 740 | 20 | 17 HRC | 8.2 % IACS |
Cold drawn | Close-tolerance bright bar for shafts machined without further heat treatment. | 650 | 780 | 12 | 20 HRC | 8 % IACS |
high-temper condition | Toughness-biased condition for large shafts and parts that still need post-HT machining. | 820 | 960 | 18 | 30 HRC | — |
QTDefault Quenched and tempered | Standard supply condition meeting JIS 930 MPa UTS / 785 MPa YS for shafts, bolts and gear blanks. | 850 | 1,000 | 17 | 31 HRC | — |
Q&T + gas/plasma nitrided case | Q&T core with 0.2–0.4 mm nitrided case for wear and fatigue on shafts and spindles. | 850 | 1,000 | 15 | 55 HRC | 7.8 % IACS |
medium-temper condition | Higher strength for loaded bolts, couplings and gear blanks with acceptable toughness. | 1,020 | 1,150 | 14 | 35 HRC | — |
low-temper (high strength) condition | Maximum practical through-hardness for small sections needing wear and high yield strength. | 1,250 | 1,400 | 11 | 42 HRC | — |
What is SCM432?
SCM432 is a medium-carbon through-hardening chromium-molybdenum steel in the JIS SCM family, equivalent to AISI 4137, sitting between SCM430 and SCM435 in carbon and strength. It is chosen for shafts, bolts and forgings that need intermediate strength with reliable hardenability, and is stocked as bar and forging stock in annealed, normalized, hot-rolled, cold-drawn, Q&T (28-32, 33-38 and 40-45 HRC) and Q&T plus nitrided conditions. The default Q&T condition gives 850 MPa yield, 1000 MPa tensile, 17 % elongation at 293 HB / 31 HRC, with service to about 400 °C and machinability 55. It requires preheat and post-weld tempering to weld and has no corrosion resistance bare; SCM435 or SCM440 is the step up when higher strength is needed. SCM432 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). SCM432 has a yield strength of 850 MPa (123 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 88% of steel grades. Elongation at break is 17% and the elastic modulus is 207 GPa (30 Msi).
What is SCM432 used for?
- shafts
- high-strength bolts
- structural forgings
Advantages
- High strength — 850 MPa (123 ksi), better than 88% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
SCM432 properties
Typical room-temperature values for SCM432-QT; bars are the position among steel grades.
Physical3
SCM432 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).
Mechanical16
SCM432 has a yield strength of 850 MPa (123 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 88% of steel grades. Elongation at break is 17% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
SCM432 is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
SCM432 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SCM432 takes about 28 MJ of energy and emits 2.1 kg of CO₂ — less than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
SCM432's machinability is good (55/100, better than 62% of steel grades); weldability fair (45/100); 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. SCM432 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SCM432
Is SCM432 easy to machine?
Machine in the annealed/normalized state or at ≤32 HRC; use coated carbide, rigid setups and generous coolant — chips are stringy at low hardness.
Can SCM432 be welded?
Preheat 200–300 °C, use low-hydrogen consumables, control interpass heat and post-weld temper/stress-relieve at 600–650 °C to avoid HAZ cracking.
Can SCM432 be formed, bent or molded?
Hot forge 1100–1200 °C then normalize; cold bending or heading only in the spheroidize-annealed condition with generous bend radii.
SCM432 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 G4053 SCM432 | 0.27 – 0.37 | 0.33 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Cr | 1 – 1.5 | 1.2 |
| Mo | 0.15 – 0.3 | 0.22 |
| Niresidual, max | ≤ 0.25 | |
| Curesidual, max | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on SCM432?
No anodizing — protect with zinc/manganese phosphate, black oxide, Zn-Ni or hard chrome; nitriding or induction hardening adds surface wear resistance.
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 SCM432 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- AISI / SAE
- 4137
How much does SCM432 cost?
SCM432 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.
SCM432 — frequently asked
What is SCM432 used for?
SCM432 is typically used for shafts, high-strength bolts and structural forgings. In short: between SCM430 and SCM435; balanced strength and toughness; nitridable Cr-Mo shaft steel.
What is the yield strength of SCM432?
SCM432 has a typical yield strength of 850 MPa (123 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 88% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is SCM432 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the annealed/normalized state or at ≤32 HRC; use coated carbide, rigid setups and generous coolant — chips are stringy at low hardness.
Can SCM432 be welded?
With care — weldability is rated fair (45/100). Preheat 200–300 °C, use low-hydrogen consumables, control interpass heat and post-weld temper/stress-relieve at 600–650 °C to avoid HAZ cracking.
What surface finishes work on SCM432?
No anodizing — protect with zinc/manganese phosphate, black oxide, Zn-Ni or hard chrome; nitriding or induction hardening adds surface wear resistance.
Can SCM432 be formed, bent or molded?
Hot forge 1100–1200 °C then normalize; cold bending or heading only in the spheroidize-annealed condition with generous bend radii.
What is the maximum service temperature of SCM432?
SCM432 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 SCM432-QT and SCM432-HR?
QT is the default condition — standard supply condition meeting JIS 930 MPa UTS / 785 MPa YS for shafts, bolts and gear blanks. HR: cheapest mill condition, bought as feedstock for forging and subsequent heat treatment. Yield strength is 850 MPa in QT versus 430 MPa in HR.
How much does SCM432 cost?
SCM432 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
- JIS G 4053 Low-alloyed steels for machine structural use — JSA (2016)
- GB/T 3077 (equivalent Cr-Mo grades) — SAC (2015)
- 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)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
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.