4140 Steel McMaster – Availability, Grades, and Practical Selection Tips
When engineers and buyers search for reliable sources of alloy steel, 4140 steel McMaster products often appear as a popular option. McMaster-Carr lists many 4140 variants in different shapes, sizes, and hardness levels. Understanding how 4140 steel performs helps you choose the right specification from McMaster or from professional steel suppliers.
🔎 What does “4140 Steel McMaster” refer to?
The term 4140 steel McMaster mainly refers to AISI 4140 chromium-molybdenum alloy steel products available on the McMaster-Carr platform. Designers normally look for:
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pre-hardened 4140
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annealed 4140
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quenched-and-tempered 4140
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4140 shafts, plates, and round bars
McMaster focuses on convenience and small-batch availability, while industrial mills supply large-volume stock.
🧪 Chemical composition of 4140 steel
The composition defines how 4140 steel McMaster behaves in service.
| Element | Typical Range (%) | Function |
|---|---|---|
| Carbon | 0.38–0.43 | Raises strength and hardness |
| Chromium | 0.80–1.10 | Improves wear and corrosion resistance |
| Molybdenum | 0.15–0.25 | Enhances toughness and high-temperature strength |
| Manganese | 0.75–1.00 | Supports hardenability |
| Silicon | 0.15–0.35 | Adds strength and shock resistance |
This alloy design gives 4140 a strong balance of hardness, toughness, and fatigue resistance.
⚙️ Mechanical properties of 4140 steel
Typical mechanical ranges for the material associated with 4140 steel McMaster include:
| Condition | Tensile Strength (MPa) | Yield Strength (MPa) | Hardness |
|---|---|---|---|
| Annealed | ~655 | ~415 | 18–22 HRC |
| Normalized | ~965 | ~655 | 28–32 HRC |
| Quenched & Tempered | 1240–1600 | 1080–1300 | 28–55 HRC |
These values explain why engineers frequently select 4140 for high-load parts.
🛠️ What forms of 4140 steel does McMaster commonly supply?
When people mention 4140 steel McMaster, they usually mean:
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4140 round bar
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4140 precision ground shaft
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4140 pre-hardened plate
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4140 threaded rod
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4140 tubing in some sizes
Shops use these products for maintenance, repair, prototyping, and small-lot production.
Large-volume manufacturers often move to specialized steel suppliers like Otai Special Steel to reduce cost and expand size range.
🧭 Applications of 4140 steel
Whether sourced from McMaster or mill suppliers, 4140 steel supports critical engineering parts, including:
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gears and gear shafts
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hydraulic cylinder rods
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crankshafts and connecting rods
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tooling holders and fixtures
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down-hole oilfield equipment
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heavy-duty fasteners
The alloy handles shock, torsion, and cyclic stress effectively.
🔥 Heat treatment options for 4140 steel
Engineers select different conditions of 4140 steel McMaster depending on job requirements:
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annealed → easier machining
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pre-hardened → ready for tooling components
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quenched & tempered → high strength plus toughness
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nitrided → wear-resistant surface with tough core
Heat treatment flexibility is one key reason for 4140’s popularity.
✂️ Machinability and weldability
4140 machines well in its annealed state. Harder conditions need rigid setups and carbide cutting tools.
Welding is possible with:
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preheating
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low-hydrogen electrodes
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stress relief afterward
Good practice prevents cracking in thick sections.
💰 Is 4140 steel from McMaster expensive?
The phrase “4140 steel McMaster” often links to cost discussion. McMaster prioritizes:
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fast delivery
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wide availability
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small quantity options
Therefore, its pricing often runs higher than mill-direct suppliers. For bulk orders, buyers usually choose professional steel service centers.
🏢 Company Advantages – Otai Special Steel
If you need a 4140 steel alternative to McMaster for larger quantities, we support you with:
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more than 10,000 tons of 4140 stock
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bars, plates, blocks, tubes, and pre-hardened material
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precision cutting and custom heat treating
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ultrasonic testing and chemical composition reports
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export packing and SGS inspection service
You get both engineering support and competitive pricing.
❓ FAQ – 4140 Steel McMaster
Q1: Is 4140 steel the same regardless of supplier?
No. Chemistry tolerance, cleanliness, and heat-treat condition may vary among suppliers.
Q2: Is McMaster 4140 pre-hardened?
Some grades come pre-hardened, others annealed. Always check the condition listed.
Q3: Can I machine McMaster 4140 directly?
Yes. Annealed grades machine easily. Harder grades need carbide tooling.
Q4: Is 4140 stronger than mild steel?
Yes. It delivers far higher strength and fatigue resistance than typical carbon steels such as 1018 or 1045.
Q5: Where can I buy larger quantities than McMaster offers?
You can source directly from Otai Special Steel for mill size and customer-specific processing.
