Understanding Ductility & Malleability: Definition, Differences, Examples, Measurement and More

Malleability and ductility are related terms and are important in engineering and manufacturing, to assess the best materials for your project, to understand ductility and malleability, today let’s start with their definitions, differences, examples of metals, measurement, calculation and some frequently asked questions.

What Is Ductility?

Ductility is a physical property that measures the ability of a material to deform plastically before fracturing. Ductility usually indicates the ability to be drawn or stretched into wire without breaking. A material is ductile if it can deform a lot before breaking, conversely, it is brittle. Knowing the ductility of materials is critical, especially in structural and mechanical applications. For example, in aerospace engineering, high-strength, low-alloy (HSLA) aluminum alloys are preferred for their high ductility, which allows them to absorb impact energy without cracking.

What are the uses of ductile metals?

– Construction: Structural steel for buildings, bridges, and other infrastructure, steel cables and wires, etc.

– Automotive:Body panels and frames of vehicles, engine components, suspension components, fuel and brake lines.

– Aerospace: Fuselage and wing structures of aircraft, landing gear components, hydraulic tubing, and fittings.

– Electrical and electronics: Copper wiring and cables, aluminum conductors, electrical connectors, and terminals.

– Manufacturing and machinery: Machine parts and components, gears and shafts, Pressure vessels and pipelines, springs and fasteners.

– Packaging industry: Aluminum cans, steel drums and containers, foil wrapping materials.

– Jewelry and decorative applications: Gold and silver jewelry, decorative metalwork, and sculptures.

– Medical and dental: Orthopedic implants, dental crowns, and bridges, surgical instruments and tools.

How do you fabricate ductile materials? Ductile materials are easier to manufacture in processes like welding, brazing, soldering, wire drawing, and extrusion.

How to Measure and Calculate Ductility?

– Percentage elongation. This is the most widely used method to measure ductility. A higher percentage elongation value indicates greater ductility. A tensile test is performed on a standardized specimen with a known initial gauge length (L0).After the test, the final gauge length (Lf) is measured. The percentage elongation is calculated as: [(Lf – L0) / L0] × 100%.

– Percentage reduction in area. During the tensile test, the cross-sectional area of the specimen reduces due to plastic deformation. The initial cross-sectional area (A0) and the minimum cross-sectional area at the fracture point (Af) are measured. A higher percentage reduction in area value indicates greater ductility. The percentage reduction in area is calculated as [(A0 – Af) / A0] × 100%.

Aluminum Ductility

When we talk about the ductility of some common metals used in CNC machining, aluminum is recognized for its high ductility, which is facilitated by its low melting point and low density. This property allows it to be easily formed into various shapes and to bend without losing strength, making it ideal for use in structures that require some flexibility. Classified as the sixth most ductile metal, aluminum can be transformed into extremely thin sheets or drawn into fine wires. The ductility of aluminum is especially apparent at room temperature compared to other metals like gold, platinum, and silver, which are also highly ductile, whereas metals such as silicon, boron, and germanium are much more brittle. While pure aluminum exhibits high ductility, its ductility can be somewhat diminished by the addition of other elements to form various aluminum alloys. However, these alloys generally maintain a moderate level of ductility. The ductility of aluminum alloys can also vary significantly with different heat treatments, which typically increase the metal’s hardness and thereby reduce its ductility compared to its annealed state. Here is the Elongation at Break in 25℃ for different aluminum alloys.

– Aluminum 3003: 40% (Annealed), 16% (H14)

– Aluminum 5052: 30% (Annealed), 18% (H32)

– Aluminum 6061: 30% (Annealed), 17% (T6)

What Is Malleability?

Malleability is also a physical property that defines the material’s ability to be shaped or molded into various forms without breaking. Malleability is important for selecting metals used in sheet metal fabrication, as it allows the metal to be easily formed and reshaped through compression and stretching techniques. When metals like copper, tin, lead, and steel exhibit malleability, being able to change form when compressed, they take on an almost dough-like quality that makes them very workable – they can be rolled out into sheets, drawn into wires, and even reshaped without damaging the continuity of the metal particles.

Is malleable a metal or nonmetal? Malleability is generally a metal property, metals are typically considered malleable materials, they can be hammered, pressed, or rolled into different shapes without breaking, while nonmetals such as wood and plastics are not malleable.

Which property is characterized by the ability to bend? Malleability describes the ability to bend and return to its original shape.

Which category of elements have the property of being malleable and ductile? Metals.

Why are most metals ductile and malleable? Most metals are ductile and malleable due to their crystal structure and the way their atoms bond together. The atoms in metals are arranged in a way that allows them to easily slide past one another, so metals can deform plastically or change shape without breaking when subjected to stress. In addition, metals have a large number of free electrons that can move throughout the material, facilitating the movement of dislocations, or defects in the crystal lattice, which can help the metal to deform plastically. However, not all metals are ductile and malleable.

How to Measure Malleability?

There are no standardized quantitative tests to measure malleability, here are some common methods to assess and compare the malleability of materials.

– Hammering or forging test. A sample of the material is placed on an anvil or a sturdy surface. The sample is then struck repeatedly with a hammer or a forging tool. The degree of deformation or flattening without cracking or fracturing is observed. Highly malleable materials can be significantly deformed without breaking.

– Rolling or pressing test. A sample of the material is passed through a rolling mill or a press. The thickness reduction or the extent of flattening without cracking is observed. Malleable materials can undergo significant thickness reductions without fracturing.

– Bend or folding test. A sample of the material, often in the form of a thin sheet or wire, is bent or folded back on itself. The number of bends or folds the material can withstand without cracking indicates its malleability. Highly malleable materials can be bent or folded multiple times without fracturing.

Examples of Ductility and Malleability

1) Ductile Metals

Most metals are examples of ductile materials, including gold, silver, platinum, copper, nickel, niobium, tantalum, etc. While some metals are not very ductile and nonmetals are not generally ductile.

2) Malleable Metals

The malleable metals examples are gold, lead, silver, aluminum, copper, nickel, iron, zinc, etc.

Which is both malleable and ductile? About these two properties, gold and silver are both highly malleable and ductile metals. But a malleable material may be not ductile, for example, lead has a high malleability but low ductility.

Ductility vs Malleability - Differences Between Malleability and Ductility

1)Stress. Ductility refers to the ability to undergo significant plastic deformation without fracturing or breaking when subjected to tensile stress, whereas malleability refers to the ability to undergo permanent deformation by compressive forces.

2)Deformation. Ductility is associated withstanding tensile forces and elongate without breaking. Malleability is associated withstand compressive forces and flatten or spread out without cracking.

3)Direction. Ductility involves deformation in the direction of the applied tensile force, resulting in elongation or stretching. Malleability involves deformation perpendicular to the applied compressive force, resulting in flattening or spreading.

4)Test methods. Ductility is typically measured by tensile tests, where a specimen is subjected to increasing tensile stress until it fractures. The percentage of elongation or reduction in cross-sectional area is used to quantify ductility. Malleability is often assessed qualitatively by observing the material’s ability to deform under hammering, rolling, or pressing without cracking or breaking.

5)Material characteristics. Ductile materials can undergo significant plastic deformation before fracture, which is desirable for applications such as wire drawing, sheet metal forming, and pipe bending. Malleable materials can be easily shaped or flattened without cracking, which is useful for applications like forging, stamping, and coining.

6) Temperature impact. Ductility of solid materials goes down when temperature increases, while malleability of solid materials goes up with increases in temperature.