Steel 4147-SPH (Spheroidize annealed)
Heat-treated state
AISI/SAE 4147 · UNS G41470
Choose for maximum cold formability/heading and easiest machining of this high-carbon Cr-Mo grade.
Values for the SPH condition
Other 4147 tempers and conditions
4147 is listed in 13 conditions; see the grade overview at 4147.
Compare all 13 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SPHThis page Spheroidize annealed | Choose for maximum cold formability/heading and easiest machining of this high-carbon Cr-Mo grade. | 390 | 640 | 25 | 10 HRC | 8 % IACS |
Solution annealed | Softest condition for machining, deep drilling and forging stock before final heat treatment. | 415 | 690 | 22 | 197 HB | — |
Hot rolled | Lowest-cost mill condition for parts that will be re-heat-treated after machining or forging. | 570 | 900 | 15 | 26 HRC | 7.8 % IACS |
Cold drawn | Straight, close-tolerance bright bar for shafts machined to size without further heat treatment. | 670 | 790 | 14 | 21 HRC | 7.8 % IACS |
Normalized | Refines forging structure and gives uniform machinable hardness before quench and temper. | 690 | 1,075 | 13 | 33 HRC | 7.8 % IACS |
QT2832Default Q&T 28–32 HRC | Standard stocked quenched-and-tempered bar/forging: best balance of strength, toughness and machinability. | 860 | 965 | 17 | 30 HRC | — |
Induction hardened | Pick for journals, pins and gear teeth needing a 55–60 HRC wear case over a tough 28–32 HRC core. | 860 | 965 | 15 | 57 HRC | 7.5 % IACS |
H-band hardenability grade | Order when Jominy hardenability band (not just chemistry) must be guaranteed for heavy sections. | 860 | 965 | 17 | 30 HRC | 7.8 % IACS |
Q&T 32–36 HRC | Higher-strength shafting, tool joints and drill-string components still readily machinable. | 980 | 1,080 | 15 | 34 HRC | — |
Q&T 36–40 HRC | For heavily loaded gears, spindles and dies where wear resistance outranks toughness. | 1,140 | 1,240 | 13 | 38 HRC | — |
Q&T 40–44 HRC | High-strength forged tooling and wear parts; machining requires carbide, grinding often preferred. | 1,280 | 1,380 | 12 | 42 HRC | — |
Q&T 48–52 HRC | Wear-critical parts such as hammers, shear blades and mill liners; low toughness, ground finish. | 1,550 | 1,720 | 9 | 50 HRC | — |
Quenched and tempered at 205 °C | Maximum hardness/wear condition; only for compression-loaded or lightly stressed wear surfaces. | 1,650 | 2,000 | 7 | 55 HRC | — |
What is 4147-SPH?
4147-SPH is 4147 heat treated to SPH — choose for maximum cold formability/heading and easiest machining of this high-carbon Cr-Mo grade. 4147-SPH has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 64% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi). 4147-SPH has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,416°C (2,581 °F). QT2832 is the default condition FabDigit quotes; SPH is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
4147-SPH properties
Typical room-temperature values for 4147-SPH; 23 are specific to this condition. Other listed values are 4147 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
4147-SPH has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,416°C (2,581 °F).
Mechanical16
4147-SPH has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 64% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
4147-SPH is rated for continuous service to 425°C (797 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
4147-SPH conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 4147-SPH takes about 29 MJ of energy and emits 2.2 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability8
4147-SPH's machinability is good (60/100, better than 83% of steel grades); weldability fair (35/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 4147-SPH
Is 4147 easy to machine?
Machine in annealed (~197 HB) or ≤32 HRC Q&T condition with rigid setups and coated carbide; above 40 HRC use ceramic/CBN or grind.
Can 4147 be welded?
Poor weldability (CE ≈ 0.85): preheat 200–320 °C, low-hydrogen consumables, interpass control and immediate post-weld temper below the tempering temperature.
Can 4147 be formed, bent or molded?
Hot forge 1150–1230 °C, finish above 900 °C and slow-cool/anneal; cold forming limited to spheroidize-annealed stock with generous radii.
What surface finishes work on 4147?
Not anodizable — use oil, manganese phosphate, black oxide, zinc or hard chrome; bake after plating to avoid hydrogen embrittlement above 40 HRC.
4147 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 |
|---|---|---|
| CSAE J404 | 0.45 – 0.5 | 0.47 |
| Mn | 0.75 – 1 | 0.88 |
| Si | 0.15 – 0.35 | 0.25 |
| Cr | 0.8 – 1.1 | 0.95 |
| Mo | 0.15 – 0.25 | 0.2 |
| P | ≤ 0.04 | — |
| Smax; resulfurized 4147 variants run higher | ≤ 0.04 | — |
| Fe | balance | — |
4147-SPH — frequently asked
What is 4147-SPH used for?
4147-SPH is typically used for forged shafts, springs and tool components. In short: higher-carbon 4140 upgrade; deep-hardening forging grade; poor weldability.
What is the yield strength of 4147-SPH?
4147-SPH has a typical yield strength of 390 MPa (56.6 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 64% of steel grades. Strength varies by condition: see the 13 listed tempers.
Is 4147-SPH easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Machine in annealed (~197 HB) or ≤32 HRC Q&T condition with rigid setups and coated carbide; above 40 HRC use ceramic/CBN or grind.
Can 4147-SPH be welded?
With care — weldability is rated fair (35/100). Poor weldability (CE ≈ 0.85): preheat 200–320 °C, low-hydrogen consumables, interpass control and immediate post-weld temper below the tempering temperature.
What surface finishes work on 4147-SPH?
Not anodizable — use oil, manganese phosphate, black oxide, zinc or hard chrome; bake after plating to avoid hydrogen embrittlement above 40 HRC.
Can 4147-SPH be formed, bent or molded?
Hot forge 1150–1230 °C, finish above 900 °C and slow-cool/anneal; cold forming limited to spheroidize-annealed stock with generous radii.
What is the maximum service temperature of 4147-SPH?
4147-SPH is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 4147-QT2832 and 4147-QT205?
QT2832 is the default condition — standard stocked quenched-and-tempered bar/forging: best balance of strength, toughness and machinability. QT205: maximum hardness/wear condition; only for compression-loaded or lightly stressed wear surfaces. Yield strength is 860 MPa in QT2832 versus 1,650 MPa in QT205.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- SAE J1268 — Hardenability Bands for Alloy H Steels — SAE International (2019)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- GB/T 3077 (45CrMo ) — SAC (2015)
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.