Top 10 Strongest Metals: Properties, Uses & CNC Machining

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A metal’s or alloy’s strength depends on its properties. When selecting a metal for a specific application, such as CNC machining, it is essential to ensure that its properties are suitable. Steel, for example, is unmatched in terms of overall strength. Tungsten is the best choice if high hardness is required, while titanium combines the properties of both steel and tungsten, making it a strong competitor.

In this guide, we look at some of the top 10 strongest metals and metal alloys used in engineering and CNC manufacturing, including tungsten, tool steel, stainless steel, titanium alloys, Inconel, and other high-performance materials. We will cover their key properties, common CNC-machined parts, and practical machining tips to help you understand which material is right for a specific application.

How Do We Measure Metal Strength?

The strength of a metal isn’t a single parameter but rather a combination of the metal’s different properties that determine its behavior. A metal can have the highest rank in one category, but rank the lowest in another. The five most crucial properties are listed below:

Tensile Strength

Tensile strength is the ability of a material to be stretched before it fractures or breaks. It is the most heavily influencing property when determining the strength of a metal because it evaluates the strength of the metal’s lattice structures.

It is measured using a testing machine that pulls a standardised sample apart at a fixed rate until it breaks. The units used to measure tensile strength are megapascals (MPa).

Yield Strength

Yield strength is the elastic limit of a metal after which it cannot return to its original shape and deforms permanently. In cases such as structural design, the yield strength outweighs the tensile strength because a bent column has already failed.

Metals don’t have a specific yield point, so it is typically measured using the same tensile-strength test method with a 0.02% offset, meaning the yield strength is the force required to permanently deform the metal by 0.02%.

Compressive Strength

Compressive strength is how well a metal resists axial loading, or compression. Typically, ductile metals that bend can withstand compressive forces well, but brittle metals have far higher compressive strength than their yield strength.

For example, tungsten has a compressive strength of 1150 MPa, which is higher than its yield strength. This makes it great for heavy loading and pressing tools.

Impact Strength

Impact strength is the ability of the material to withstand a sudden force or blow before breaking. It is typically measured using a test, usually the Charpy or Izod pendulum test, in which a pendulum strikes a sample of metal with a V-notch cutout.

An impact test highlights a key factor in metals: hardness and impact strength are inversely proportional. For example, hardened steel tools retain their edge longer and better, but they can chip under shock.

Hardness and the Mohs Hardness Scale

Hardness is a measure of how well a metal’s surface or area resists scratches and indentation. Engineers use the Mohs scale, which ranks from 1 (talc) to 10 (diamond), to test hardness, while indentation is measured using the Brinell or Rockwell scales.

Strength Type	What It Measures	Unit	Common Test
Tensile Strength	Resistance to being pulled apart	MPa	Tensile (pull) test
Yield Strength	Stress at which permanent deformation begins	MPa	Tensile test (offset method)
Compressive Strength	Resistance to being crushed	MPa	Compression test
Impact Strength	Ability to absorb sudden shock	Joules	Charpy / Izod test
Hardness	Resistance to scratching or indentation	Mohs / Brinell / Rockwell	Mohs scale, indentation tests

The 10 Strongest Metals Ranked

Rank	Metal	Tensile Strength (MPa)	Yield Strength (MPa)	Mohs Hardness	Melting Point (°C)	Common Uses
1	Tungsten	980–1,510	750	7.5	3,422	Cutting tools, tungsten carbide, filaments
2	Steel Alloys	400–2,000+	250–1,600	4–4.5	1,370–1,540	Construction, automotive, machinery
3	Stainless Steel	515–1,300	200–1,000	5.5–6.3	1,400–1,530	Kitchenware, medical tools, architecture
4	Chromium	418	316	8.5	1,907	Plating, stainless steel alloying
5	Titanium	240–1,400	170–1,100	6	1,668	Aerospace components, implants
6	Inconel	830–1,400	460–1,100	6	1,390–1,425	Jet engines, extreme environments
7	Tool Steel	640–2,000	380–1,650	7–8	1,400	Cutting tools, dies, drills
8	Iron	200–540	50–250	4	1,538	Steel production, construction, cast parts
9	Magnesium Alloys	220–380	130–280	2.5	650	Lightweight aerospace and auto parts
10	Copper Alloys	210–1,400	70–1,000	3	900–1,085	Wiring, marine hardware, bronze parts

1. Tungsten

Tungsten has the highest tensile strength of 980MPa and the highest melting point of 3,422 C among all metals. The metallic bonds and body-centred lattice structure of tungsten lead to exceptional strength, even resisting deformation at high temperatures.

The only trade-off is that tungsten has low impact strength, which means it can’t handle shock and shatters. It is typically made into a tungsten-carbon compound called tungsten carbide, which has a Mohs hardness of 9, or alloyed with nickel and iron.

Tungsten and its alloys are often used to make counterweights, heat sinks, electrodes, radiation shielding components, and high-temperature tooling. Tungsten carbide, on the other hand, is used primarily for cutting tools, wear-resistant inserts, dies, and mining components.

Carbide tooling can be used for some tungsten alloys, while diamond tooling and grinding are often preferred for tungsten carbide. Use conservative cutting parameters to avoid excessive cutting forces, which can cause cracking or edge chipping.

2. Steel and Steel Alloys

Steel is a carbon and iron alloy whose strength depends on its composition and heat treatment. Alloying elements such as chromium, vanadium, and molybdenum can be used to alter toughness and fatigue resistance further. This means steel has a large range of alloys with different properties and strengths that suit different applications across various industries.

Typical CNC-Machined Parts: Steel and alloy steels are among the most widely machined metals and are used for shafts, gears, brackets, housings, machine components, tooling, and structural parts. High-strength alloy steels such as 4130 and 4140 are particularly suitable for components exposed to high loads, impact, or fatigue.
CNC Machining Tips: The machinability of steel varies significantly based on its grade and hardness. Low-carbon steels are generally easier to machine, while hardened alloy steels require more rigid setups and wear-resistant tooling. Depending on the operation, carbide, ceramic, or CBN tools may be required for hardened steel above approximately 45 HRC. Maintain stable cutting conditions and avoid prolonged contact, as this can generate excessive heat and accelerate tool wear.

3. Stainless Steel

Stainless steel is a steel alloy that distinguishes itself from other steel due to the presence of chromium,10.5% of composition to be exact. This chromium helps form a passive oxide layer that shields against rust.

Typical CNC-Machined Parts: Stainless steel is often CNC-machined into valve bodies, shafts, medical components, pump parts, fittings, food processing components, and corrosion-resistant housings. Austenitic steel grades such as 304 and 316 have tensile strength of about 515-620 MPa with excellent corrosion resistance; this versatility makes it great for things like surgical equipment and food processing hardware.
CNC Machining Tips: Stainless steel can be challenging to machine because some grades have low thermal conductivity and a strong tendency to work harden. Use sharp tools, maintain a consistent feed rate, and avoid allowing the tool to rub against the workpiece. For hardened stainless steels, such as 17-4 PH under certain heat-treated conditions, more wear-resistant carbide tooling and optimized cutting parameters may be necessary.

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4. Chromium

Chromium has a rating of 8.5 on the Mohs hardness scale, making it the hardest pure metal, but its tensile strength is still moderate, around 420 MPa, making it brittle. Chromium isn’t used purely as a structural element, but rather it is valued as an alloying element that is typically used to make stainless steel.

Chromium is rarely machined as a pure metal due to its brittleness and challenging machinability. Instead, it is more commonly found in stainless steel, tool steel, and other hard alloys used for shafts, wear-resistant components, and industrial tooling. When machining chromium-containing alloys, use rigid fixturing, sharp, wear-resistant tools, and controlled cutting forces to minimize vibration and tool wear.

5. Titanium and Titanium Alloys

Pure titanium has low tensile strength, around 240-434 MPa, but it is alloyed to make an alpha-beta titanium alloy, Ti-6Al-4V, which contains aluminium and vanadium. This titanium alloy is the common form of titanium used across all industries. Its tensile strength reaches 1000 MPa, while beta titanium alloys can exceed 1200MPa.

It is lighter than steel, with a density of 4.5g/cm3, giving it the best strength-to-weight ratio of any metal. Additionally, it is biocompatible and corrosion-resistant, which makes it highly desirable in aircraft frames and implants.

6. Inconel

Inconel is a nickel-chromium alloy that has high strength retention at extreme temperatures. Inconel 718 has a tensile strength of 1220 -1400MPa and can retain its strength at temperatures as high as 700 °C.

Inconel resists oxidation, making it ideal for jet engines and gas turbine components. The only drawback is cost and machinability, as it hardens instantly when cutting.

7. Tool Steel

Tool steel is a high-carbon alloy that contains molybdenum, tungsten, or chromium as alloying elements and is made for high-impact resistance tools that can retain their edge. Air-hardened A2 tool steel is rated 8 on the Mohs scale, with a tensile strength close to 1860 MPa and a hardness of 60+ HRC.

Different tool steel classes have different applications. For example, high-speed steel is used for drilling and mining, while high-impact grades are used for chisels and punches. The only trade-off is that the harder the metal, the lower the impact toughness.

8. Iron

Pure iron is soft compared to modern alloys, with a tensile strength of 200- 450 MPa and an AR4 rating on the Mohs hardness scale. It is valued because it is the primary constituent element in stainless and tool steel.

All steels start as iron and are later alloyed with other elements depending on the desired properties. Cast iron, which contains 2-4 % carbon, has excellent compressive strength, which is great for machine tool bases and engine blocks. Because cast iron produces abrasive chips and dust that can accelerate tool wear, carbide tools and effective chip extraction are recommended.

9. Magnesium Alloys

Magnesium is the lightest metal with a density of only 1.7g/cm3. Alloys such as AZ91 have a tensile strength range of 220-380 MPa. This may seem low in number, but in terms of strength-to-weight ratio, it’s great.

Magnesium alloys are used in aircraft gearbox housings, seat frames, and electronic enclosures. The only constraint is that the design must account for low hardness, galvanic corrosion, and the fire hazard of small chips during machining. Use sharp tools, avoid excessive heat buildup, and ensure efficient chip evacuation.

10. Copper and Aluminum Alloys

Pure copper and pure aluminium are weak and soft. Their alloys are what engineers desire in machinery and systems. Beryllium copper has a tensile strength of 1400 MPa with great conductivity. Bronze, a copper-tin alloy, is used in bearings and marine applications due to its corrosion and wear resistance.

Copper and aluminum alloys are widely machined into electrical connectors, heat sinks, housings, brackets, bushings, and lightweight structural components. Aluminum alloy, like the 7000 series, can reach a tensile strength of 570 MPa, which is great for aircraft structural components when paired with its low density. Copper produces long, sticky chips, and some aluminum grades may cause built-up edge.

Natural Metal vs. Alloy: Which Is Stronger?

Based solely on tensile strength, pure tungsten is one of the strongest naturally occurring metals, though it can be outperformed by many engineered alloys. These alloys’ exceptional strength comes from their carefully controlled compositions, heat treatments, and microstructures, which hinder plastic deformation.

Maraging steels, for example, can exceed 2,000 megapascals (MPa) in tensile strength, and some precipitation-hardened nickel-cobalt alloys can reach approximately 2,400 MPa. Although tungsten can achieve significantly higher strength through processing and alloying, its mechanical properties depend strongly on purity, processing conditions, and temperature.

Therefore, selecting the strongest metal should not be based on tensile strength alone. Hardness, toughness, fatigue resistance, temperature resistance, corrosion resistance, and machinability should all be considered alongside tensile strength when determining the suitability of a material for a specific application.

Conclusion

The top 10 strongest metals are a diverse group of materials, and there is no single “strongest metal” for every application. Tungsten stands out for its exceptional strength and high-temperature performance. Maraging steel, precipitation-hardened alloys, titanium alloys, and Inconel provide an excellent combination of strength and other engineering properties.

When choosing a strong metal, tensile strength should be just one factor in the decision-making process. Depending on the application, hardness, toughness, fatigue resistance, corrosion resistance, weight, operating temperature, and machinability can be equally important.

In CNC machining, a material’s properties directly affect tooling, cutting parameters, machining time, and achievable tolerances. It is essential to select the right material and machining strategy together to produce reliable, high-precision parts.

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FAQs

Tungsten vs Titanium: Which Is Stronger?

Tungsten and titanium are the strongest metals with different properties. Tungsten has higher tensile strength, while titanium has a better strength-to-weight ratio, being only a ¼ of tungsten.

Property	Tungsten	Titanium
Tensile Strength (MPa)	980–1,510	240–1,400 (alloys)
Yield Strength (MPa)	750	170–1,100
Mohs Hardness	7.5	6
Density (g/cm³)	19.3	4.5
Strength-to-Weight Ratio	Low	Excellent
Corrosion Resistance	Good	Excellent
Melting Point (°C)	3,422	1,668
Cost	Moderate–High	High
Common Uses	Cutting tools, armor, filaments	Aerospace, implants, sports gear

Is Titanium Stronger Than Steel?

Titanium is stronger than steel by weight, but not in absolute terms. Titanium has a tensile strength of 900-1000MPa, which is lower than that of tools and hardened steels.

What Is the Hardest Metal on the Mohs Scale?

The hardest metal on the Mohs scale is chromium at 8.5, while tungsten carbide is at 9. It is a metal carbon compound.