Alloy steel
High strength and toughness, fatigue resistant.
| Applications | CNC machining produces parts with excellent mechanical properties, accuracy and repeatability |
| Strengths | Excellent mechanical properties, high accuracy & repeatabillity |
| Weaknesses | Greater geometry restrictions than 3D printing |
| Price | $$$$$ |
| Lead time | < 10 days |
Machining Alloy steel
Alloy steels machine predictably in the annealed or normalized condition, and pre-hardened grades such as 4140HT (around 28–32 HRC) can be milled and turned directly with carbide tooling. Machining pre-hardened stock avoids the distortion that heat treating a finished part can introduce, so critical dimensions stay where you machined them.
For parts that must be heat treated to higher hardness, we rough machine first, heat treat, then finish critical features afterwards so tolerances hold. On our CNC mills and lathes we hold ±0.025 mm on critical alloy steel features, with grinding available where a drawing calls for tighter limits or fine surface finishes.
Compared with mild steel, alloy steel's higher strength means more rigid workholding, sharper carbide grades and flood coolant to manage heat, all standard practice across our 50+ machine floor.
Common Grades We Machine
- 4140 / EN19 (chromoly) - The general-purpose alloy steel: good strength, toughness and wear resistance. Shafts, fixtures, tooling, high-stress brackets.
- 4340 / EN24 - Nickel-chromium-molybdenum grade with higher strength and impact resistance for heavily loaded parts such as gears, couplings and structural components.
- 8620 - Case-hardening grade: carburized parts get a hard, wear-resistant surface over a tough core; the standard choice for gears and pinions.
- Other grades on request - We source specific alloy steel grades with mill certificates and full material traceability.
Applications by Industry
- Oil & Gas - valve internals, drilling tool components and high-pressure fittings that need strength in harsh environments.
- Semiconductor - structural machine frames, load-bearing shafts and precision tooling components.
- Automotive - shafts, gears and transmission parts produced with high repeatability.
Surface Finishing Options
- Black oxide - mild corrosion resistance and a uniform dark finish with virtually no dimensional change.
- Zinc or nickel plating - corrosion protection for parts exposed to moisture or handling.
- Phosphate coating - wear resistance and oil retention on sliding or threaded parts.
- Precision grinding and polishing - tight-tolerance bearing surfaces and fine surface finishes after heat treatment.
See our surface finishing services for the full range.
Frequently Asked Questions
What tolerances can you hold when CNC machining alloy steel?
We hold ±0.025 mm on critical features across milling and turning, and use precision grinding where drawings call for tighter limits or finer surface finishes.
Can you machine pre-hardened alloy steel?
Yes. Pre-hardened stock around 28–32 HRC, such as 4140HT, is machined directly with carbide tooling. For higher hardness we rough machine, heat treat, then finish critical features.
Should I choose 4140 or 4340?
4140 covers most general-purpose needs with good strength and toughness at lower cost. Choose 4340 when the part sees higher loads or impact and needs the extra strength of the nickel-alloyed grade.
Do you provide material certificates?
Yes. Alloy steel parts ship with mill certificates and full material traceability, which our semiconductor and oil & gas customers require as standard.
Precision Alloy steel Manufacturing in Singapore
Need complex Alloy steel parts manufactured to tight tolerances? Explore our 5-axis simultaneous CNC machining and certified ISO Class 6–8 cleanroom assembly capabilities.
Speak with Our Sales & Engineering Team
Explore how Shine's Singapore precision CNC machining and cleanroom assembly integrate into your global supply chain. We welcome technical consultations, mutual NDAs, and facility audits.
- Mutual NDA executed within 24 hours
- ISO 9001:2015 certified & Cyber Essentials mark
- 24–48h engineering DFM feedback & formal RFQ pricing