The field of study known as "materials science and engineering" that focuses on the discovery and development of new materials draws on many different academic fields.
New materials always lead to new inventions and advancements, regardless of whether you work in chemical or mechanical engineering.
Materials science and engineering examines the entire life cycle of a material from its conception to its final form, including its properties, structure, and functionality.
Electronics, communications, transportation, manufacturing, medicine, recreation, ecology, and the energy sector could all be affected by engineering; the mechanical, electrical, optical, and magnetic properties of materials could be of interest.
Metallurgy is both an art and a science, with the latter two focusing on the production of metals and alloys with useful properties. In order to use this applied science to solve real-world problems, you must first understand the nature and composition of metals and their alloys.
Steel has been the most important engineering material for several centuries, and it is also the most important metallurgical material of the last few hundred years.
Nonetheless, ceramics, plastics, and composite materials pose a threat to this dominance in a variety of fields.
Materials science and engineering is one of the most varied fields of study today, encompassing not just metallurgy but also glass and ceramic technology, mineralogy, physical and inorganic chemistry, solid-state physics, and polymer science.
Table of Contents
What Is Metallurgy?
Metals are processed through metallurgy from the time they are extracted from their ores until they are ready for final use. They take a look at the atomic level of the metal to learn about its properties.
The metal's microstructure and its elastic and plastic properties are determined by its mechanical properties.
The chemical composition of an alloy is the proportion of each element within the total mass of the alloy. Chemical make-up, temperature, and mechanical treatment are just some of the variables that can affect a material's microstructure.
Metals and alloys are indispensable to modern society. They are used to create a wide variety of machines, bridges, vehicles, and buildings.
A better and more plentiful metal supply could be a boon to the economy.
Most metals occur naturally as highly reactive minerals.
Gold, silver, platinum, and mercury are all elements that can be mined from the Earth's crust in a Free State. Metals with slow reaction rates are barely affected by air, water, carbon dioxide, and other naturally occuring nonmetals.
Naturally occuring substances that include a metal or a compound of that metal are called minerals. When a valuable metal can be extracted at a reasonable cost from a particular material, we call that material an ore. Two of nature's most vital ingredients, oxygen and carbon dioxide, can be found in the air we breathe. The Earth's crust is rich in silicon and sulphur.
In addition to sodium and chloride, chloride ions are also widely distributed in seawater (obtained from dissolved salts). Ions are the predominant form in which most metals are found because of the positive electrical charge they carry. These metals can be extracted from a wide range of minerals, such as oxides, silicates, carbonates, and halides.
Metallurgy Forming And Processing
Metals are widely used in today's technology because they can be easily fabricated into various shapes. Since then, hundreds of metalworking methods have been developed to serve a wide range of purposes. The number of distinct classes that these procedures can be placed into is, however, constrained by the nature of the force employed in the creation of the workpiece.
Compression, shearing, bending, and tension are all types of these processes. the direct compression If you apply pressure directly to the metal surface, the metal will bend in an arc in the direction of the force.
Indirect compression techniques typically employ tensile pressures, though substantial indirect compressive forces may be provided by the workpiece's reaction to the die.
Some common examples include extrusion, pipeline construction, deep drawing of the cup, and wire pulling. For the metal to flow, there must be a combination of high pressures in both of the main directions.
An expansion-type forming method involves applying tensile stresses to a metal sheet while rolling it around a die outline.
Large enough shearing forces tear the metal in the shear plane, while bending moments cause the metal sheet to deform in the bending direction. Figure 1 is an oversimplified representation of these procedures.
Hot working and cold working are the two main categories used to classify the processes used to work metal.
"Hot-working" refers to a process of deformation that takes place in conditions of high temperature and high strain rate, wherein recovery processes may be carried out simultaneously. When recovery processes fail, however, cold working deforms.
Strain hardening and a distorted grain structure caused by deformation are rapidly reversed in hot working through recrystallization and grain development.
However, because the recovery mechanisms can keep up with the deformations, hot working still allows for extremely large deformations to occur.
"Hot working" describes a process in which the flow stress remains relatively constant. Because flow stress decreases with increasing temperature, less energy is required for deformation when working at higher temperatures as opposed to those at room temperature. The flow stress increases with the degree of deformation because cold working does not enhance strain hardening.
Unless the effects of cold work are counteracted by the annealing process, the total plastic deformation without fracture is less for cold working than for hot working.
You need to understand that the difference between cold and hot functioning is not arbitrary.
Most commercial metal alloys require a hot working procedure to be performed at a relatively high temperature in order to achieve a high rate of recrystallization.
However, lead and tin recrystallize quickly at room temperature after significant deformations, making their handling at room temperature analogous to hot working.
Since 1093°C is below the recrystallization temperature of tungsten, working it in the steel hot work range is also considered a cold work.
Overview of Physical Properties of Metals
A material's physical qualities may be used to tell it apart from others. Physical and mechanical qualities are generally seen as interchangeable in the context of metallurgy, however this is not always the case.
The technique of testing is the best way to differentiate between physical and mechanical qualities. Physical qualities may be measured without altering the material, while mechanical properties need the use of force.
However, the physical qualities of a substance may be affected by its surroundings. Thermal expansion and contraction, for example, causes metals to have a larger density at lower temperatures.
In addition, a variety of external influences influence the substance's colour and appearance, both of which are considered physical qualities.
Metals' physical characteristics include:
- Coatings that prevent rusting
- Density
- Fuseable material
- The thermal conductivity
- The ability to generate and transfer heat
- Expansion due to heat
- The ability to conduct electricity.
- Electromagnetic characteristics
Corrosion Resistance
There is a wide variety of corrosion. Corrosion is affected by a number of variables, such as the surrounding environment and how the material is used.
Rust, which forms on exposed ferrous metal, is one of the most common forms of corrosion.
The ability of a material to resist the reaction that would normally cause it to move towards a more stable state is what is meant by "corrosion resistance."
Corrosion cannot take hold because an inert layer forms on their exteriors. But stainless steel is a common alloy because of its corrosion resistance in many contexts.
In contrast to carbon steel, stainless steel alloys may be resistant to surface corrosion in conditions that would typically promote corrosion, such as wet, acidic, or high heat.
Density
Density is calculated by dividing the mass (M) of an object by its volume (V) (V). Some people, inspired by legends like "the golden crown," once proposed using density as a means of verifying the genuineness of gold.
However, gold is an excellent choice for density testing due to its density of 1,206 lbs. per cubic foot.
Alloys with lower densities are preferable for industrial applications. Although both types of steel weigh roughly 494 lbs. per cubic foot, stainless steel is lighter. Aluminum has about a third the density of steel, while steel has a density that is roughly two-thirds that of titanium.
A steel product would be roughly three times as heavy as an aluminium one due to steel's greater density.
Steel's high hardness and strength mean that it often outperforms more expensive, less dense materials despite requiring a thinner profile.
Eagle Alloy and Eagle Precision frequently utilise unique carbon and stainless steel alloys to cast intricate, thin-walled components. The casting alloy plays a role in shaping the development, production, and finishing processes of each individual cast component.
Melting Point
At standard atmospheric pressures, it is the temperature at which a substance changes from a solid to a liquid. An alloy's suitability for a given use may depend critically on its melting point.
There is a direct relationship between the chemical makeup of an alloy and its melting point. Tin and aluminium alloys, for instance, melt at considerably lower temperatures than iron and nickel alloys.
The melting point is an important parameter to monitor during metal production. Due to the higher melting temperatures of steel, sand casting techniques such as air set or shell mould casting are required.
Aluminum can be cast using steel moulds because it has a lower melting point than steel.
Thermal Properties
As a result of the laws of thermodynamics, temperature tends to rise. These three characteristics are essential when deciding on the best alloy for a specific use.
- The heat capacity or specific heat of a material is a measure of how much energy is needed to cause a temperature change.
- Thermal conductivity is the rate at which heat can be transferred through a substance; all metals have a high thermal conductivity. Both thermal and electrical conductivity are related but distinct properties. Metals like copper and gold, which are renowned for their electrical conductivity, are also excellent heat conductors.
- Heating causes metals to expand, while cooling causes them to contract. This quality is essential in developing casting tools for metal. Patterns and moulds need to be larger than the final product to account for the items' shrinking size during the cooling process.
Magnetic Properties
How the material responds to an applied magnetic field is indicative of its magnetic properties. Diamagnetic, paramagnetic, ferromagnetic, antiferromagnetic, and ferrimagnetic are all possible descriptions of the magnetic response.
Steel and other ferrous metals are magnetic because iron is one of the most magnetic elements found naturally in the world.
How To Evaluate Materials – Properties To Consider
Chemical composition and internal structure, such as grain size or crystal structure, influence the mechanical and physical characteristics of materials.
Processing may have a significant impact on mechanical characteristics because it rearranges the interior structure.
Physical qualities like density and conductivity may be affected by metalworking operations or heat treatment, although these impacts are typically negligible.
When numerous alloys meet the service parameters, mechanical and physical qualities are critical in determining which alloy is best suited for a specific application. Almost always, the engineer creates a component whose performance falls within a predetermined set of parameters.
High performance in one area may be associated with inferior performance in another since many mechanical qualities are interconnected. Higher ductility, as an example, may be sacrificed in order to attain greater strength.
Understanding the product's surroundings can help you choose an appropriate material for the job at hand.
Product designers may use this knowledge to narrow down their options for materials for a specific application by learning about some of the most prevalent mechanical and physical qualities.
- Conductivity
- Corrosion Resistance
- Density
- A property of being both flexible and malleable.
- Stiffness / Elasticity
- Fracture Toughness
- Hardness
- Plasticity
- A measure of a material's tensile strength, shear strength, or yield strength.
- Toughness
- Wearing resistance is a good thing.
Conductivity
A material's thermal conductivity measures how much heat it can move through it. One degree per unit of time, per unit of cross-sectional area, and per unit of length are the units of measurement for this phenomenon.
As insulators, materials with low thermal conductivity may be employed, as heat sinks, materials with high thermal conductivity.
Heat exchangers and refrigeration might benefit from metals with high thermal conductivity.
High-temperature applications may make advantage of materials with low thermal conductivity, but many high-temperature components need materials with high thermal conductivity, making environmental knowledge essential.
Electrical conductivity, which measures the amount of electricity passed through a material with a known cross-section and length, is quite comparable.
Corrosion Resistance
Natural chemical or electrochemical assaults by the oxygen, moisture, or other factors may cause corrosion resistance in a material.
In addition to pitting, galvanic response and stress corrosion, there are numerous more types of corrosion (many of which will be discussed in other newsletter editions).
Using a linear extrapolation, corrosion resistance may be represented as the greatest depth in mils to which corrosion would penetrate during the course of one year.
There are materials that are naturally resistant to corrosion, while others need additional plating or coatings to protect them. Even if a metal is part of a family that is resistant to corrosion, it is nevertheless vulnerable to the unique environmental circumstances in which it is being used.
Density
An alloy's density may be represented in terms of pounds per cubic inch (pci), grammes per cubic centimetre (gcc), or pounds per cubic metre (pcm). The alloy's density will determine the weight of a component of a given size.
There are several applications where weight is critical, such as aerospace and automotive.
For lighter components, engineers may search for alloys that are less dense, but they must also take into account the strength to weight ratio. If a lower density material's strength is inadequate, a greater density material like steel may be the better option.
The greater density of such a component may be compensated for by making it thinner, which would use less material.
Ductility / Malleability
When a load is removed, a material's ductility is defined as its capacity to flex plastically (i.e., stretch) without cracking.
A wire may be made out of a particular metal by stretching it. Using a tensile test, ductility may be quantified as a percentage of elongation or a decrease in the cross-sectional area of the sample before failure, depending on the application.
In addition to determining the Young's Modulus or modulus of elasticity, a tensile test may also be used to estimate the stress/strain ratio utilised in many design calculations.
All other metalworking operations, including rolling and drawing, are made easier by the ability of the material to resist cracking or breaking. Contrary to this, cold-working procedures like this one tend to make a metal less malleable.
The capacity of a metal to be shaped without breaking is referred to as its malleability. Compressive stress is utilised to roll or press the material into smaller sheets. High malleability means that a material will be able to handle more stress before breaking.
Elasticity Stiffness
If you remove a force from a material, it has a propensity to revert to its previous size and form. Elasticity Elastic materials, in contrast to plastic ones (which can't be changed back to their original form after tension is removed), revert to their original shape once stress is removed.
Stubbornness may be quantified using the Young's Modulus, a ratio of stress to strain that measures a material's ability to resist stress (the resulting deformation).
The stiffer a material is, the higher its Modulus, which means that more stress results in less deformation.
In contrast to glass, rubber is a material with a low Modulus and a high Stiffness, which is the opposite of glass. For applications where stiffness is critical, this is a critical design concern.
Fracture Toughness
Material impact resistance is a measure of how well a material can handle a sudden change in its environment. If the force is applied over a lengthy period of time, it will have less of an impact than if the force is given in a short period of time. It is thus important to consider impact resistance when the application entails high risk of impact.
Metals that function well under static stresses may fall apart when exposed to dynamic loads or collisions. A Charpy test, in which a weighted pendulum hits a sample in the opposite direction of a machined V-notch, is a standard way to evaluate the impact in the lab.
Hardness
The capacity of a substance to resist permanent indentation is known as hardness (that is, plastic deformation). When it comes to protecting against wear and tear, the tougher the material, the more resistant it is.
The word hardness, thus, also refers to a material's resistance to scratching, abrasion, or cutting, as well as its local surface stiffness.
It is possible to determine a material's hardness by applying techniques such as Brinell, Rockwell, and Vickers that measure the depth and area of depression by a harder substance such as a steel ball or diamond.
Plasticity
Elongation refers to the ability of a solid substance to return to its original shape after being exposed to forming forces. A property that permits materials to be bent or twisted into a new form that will remain with them after use. At the yield point, materials change from an elastic to a plastic state.
Strength – Fatigue
Stresses (such as loading and unloading) that are recurring or variable and have maximum values smaller than the material's tensile strength may cause fatigue and, eventually, fracture.
In addition, increasing stress speeds up failure time and vice versa, hence stress and failure cycles are linked.
When we talk about "fatigue limit," we're talking about the greatest amount of stress that a metal can endure in a particular number of cycles. Instead, the fatigue life measurement fixes the load and determines how many load cycles a material can tolerate before failing.
Fatigue strength is a significant factor when designing components that are exposed to repeated loads.
Strength – Shear
If the direction and amplitude of the stress are critical, shear strength is a significant factor.
Shear occurs when the metal's internal structure slides against itself at the granular level due to directed pressures.
Strength – Tensile
When it comes to evaluating the properties of metals, one typical attribute to look at is the Tensile, or Ultimate, Strength. A metal's tensile strength measures how much force it can take before it breaks.
The metal will stretch in the lab, but it will snap back to its original shape once it passes through the elastic deformation zone. After reaching the point of permanent or plastic deformation (Yield), it remains the stretched shape even if the force is removed.
The final fracture occurs at the Tensile point, when the metal is under the most stress. Using this method, it is possible to distinguish between brittle and flexible materials.
Mega Pascals (MPa) or pounds per square inch are units used to express tensile or ultimate tensile strength.
Strength – Yield
Tensile strength and Yield Strength both indicate the point at which the material is no longer able to return to its original form or position. Rather of being elastic, deformation shifts to plastic.
The Yield Point is a factor in design calculations because it helps engineers determine when dimensional integrity has been compromised under stress.
Yield strength is also measured in Newtons per square millimetre (Mega Pascals or MPa) or pounds per square inch, much as tensile strength.
Toughness
At a particular temperature, toughness is determined by performing the Charpy impact test, which is identical to the Impact Resistance test. Materials may become more brittle at low temperatures because of the decreased impact resistance.
It's typical for Charpy values to be mandated in ferrous alloys when low temperatures are present in the application (for example offshore oil platforms, oil pipelines, etc.) or where instantaneous loading is a concern (e.g. ballistic containment in military or aircraft applications).
Wear Resistance
Materials are judged on their capacity to stand up to the effects of friction between two different materials. Wear resistance is a measure of this ability.
In addition to adhesion, abrasive methods like as scuffing, scraping, gouging, and galling exist. Managing wear on the softer metal might be a design consideration when the materials have varying degrees of hardness.
Because of the presence of foreign elements, even rolling might produce abrasion. The amount of mass lost for a given number of abrasion cycles at a particular load is one way to gauge wear resistance.
A metal's mechanical and physical qualities, when taken into account, may help in the selection process.
Metallurgical specialists can help you choose a material that gives the performance you require while also being cost-effective due to the wide variety of materials available and the ability to adjust attributes via alloying and heat treatment.
Conclusion
Discovery and improvement of new materials is the main focus of materials science and engineering. It looks at the properties, structure, and functionality of a material throughout its entire existence, from its inception to its final form. Both an art and a science, metallurgy is concerned with the design and manufacture of metals and alloys for specific purposes. Not only does it include metallurgy, but also glass and ceramic technology, mineralogy, physical and inorganic chemistry, solid-state physics, and polymer science, making it one of the most multifaceted areas of study today. These days, no modern society could function without metals and alloys, so it stands to reason that a better and more plentiful metal supply would be good for business.
In a Free State, mining for precious metals from the Earth's crust is a viable industry. Extracting metals from their naturally occuring oxides, silicates, carbonates, and halides is known as metallurgy. Extrusion, pipeline building, deep drawing of the cup, and wire pulling are just a few examples of the hundreds of metalworking techniques that have been developed to meet a wide variety of needs. Most metalworking processes can be broken down into two broad groups: hot working and cold working. When compared to cold working, hot working is a deformation process that occurs under conditions of high temperature and high strain rate.
Deformation energy can be reduced and the flow stress can be held constant during hot working. When compared to hot working, cold working results in less total plastic deformation without fracture because the flow stress increases with the degree of deformation. Lead and tin, unlike most commercial metal alloys, recrystallize quickly at room temperature following significant deformations, making their handling at room temperature analogous to hot working. Because of its resistance to corrosion and its high hardness and strength, stainless steel is a widely used alloy. You can determine an object's density by dividing its mass (M) by its volume (V) (V).
As a result of its density of 1,206 lbs. per cubic foot, gold makes for a great density testing medium. Low-density alloys are preferable for use in industrial settings. Sand casting methods like air set or shell mould casting are required during metal production because of the melting point's significance. How much energy is required to cause a temperature change is quantified by a material's heat capacity or specific heat.
When it comes to transferring heat, all metals are extremely efficient. Different types of magnetic properties, such as diamagnetic, paramagnetic, ferromagnetic, antiferromagnetic, and ferrimagnetic, can be used to describe the magnetic response. The mechanical and physical properties of a material can be affected by its chemical composition and internal structure, such as grain size or crystal structure. Mechanical properties can be drastically altered by various processes, and metalworking and heat treatment can influence physical properties such as density and conductivity. Understanding the most common mechanical and physical qualities can help product designers narrow down the options for materials for a specific application.
Heat exchangers, refrigerators, and other high-temperature applications depend on metals with high thermal conductivity, electrical conductivity, corrosion resistance, and ductility/malleability. In the same way that electrical conductivity measures the amount of current flowing through a material of known cross section and length, thermal conductivity does the same for heat. Ductility is defined as the ability to bend plastically without cracking, while corrosion resistance is measured as the maximum depth in mils to which corrosion would penetrate over the course of one year. Density is expressed as a ratio between the volume and the length of a side (pcm). Engineers may look for less dense alloys to make lighter parts, but the strength-to-weight ratio must also be considered.
The stress-to-strain ratio of a material can be approximated by means of a tensile test. The metal's resistance to cracking or breaking facilitates rolling and drawing processes. The malleability of metals refers to their ability to take on new forms without cracking, while the elasticity of materials describes their capacity to return to their original shape when stress is removed. Stress-strain ratio (also known as Young's Modulus) is a measure of a material's toughness (the resulting deformation). Unlike glass, rubber has a high Stiffness but a low Modulus.
When the application poses a high risk of impact, the material's impact resistance—a measure of its ability to withstand a sudden change in its environment—becomes crucial. One common laboratory evaluation of the effect is the Charpy test. The depth and size of the depression made by a harder substance are used by methods like the Brinell, Rockwell, and Vickers hardness scales to determine the material's hardness. Plasticity is the property of a solid to regain its shape after being deformed by applied forces, and fatigue is the maximum stress that can be applied repeatedly to a metal without causing permanent deformation. The two types of strength that can be measured are tensile and shear. Tensile strength measures the amount of force that can be applied before breaking, while shear strength measures the orientation and magnitude of the stress.
Components subjected to repeated loads should be designed with fatigue strength in mind, while yield strength refers to the stress at which a material stops recovering its original shape or size. Tensile or ultimate tensile strength can be expressed in units called mega pascals (MPa). The Yield Point, expressed in either MPa (Mega Pascals) or psi (pounds per square inch), is an important parameter in design calculations. The Charpy impact test is used to determine toughness, while wear resistance is quantified by calculating the mass lost over a specified number of abrasion cycles under a specified load. The wide variety of materials and the ability to adjust attributes via alloying and heat treatment mean that metallurgical experts can help you choose a material that gives the performance you require while still being cost-effective.
Content Summary
- The field of study known as "materials science and engineering" that focuses on the discovery and development of new materials draws on many different academic fields.
- These metals can be extracted from a wide range of minerals, such as oxides, silicates, carbonates, and halides.
- Hot working and cold working are the two main categories used to classify the processes used to work metal.
- The technique of testing is the best way to differentiate between physical and mechanical qualities.
- However, the physical qualities of a substance may be affected by its surroundings.
- But stainless steel is a common alloy because of its corrosion resistance in many contexts.
- Aluminum has about a third the density of steel, while steel has a density that is roughly two-thirds that of titanium.
- There is a direct relationship between the chemical makeup of an alloy and its melting point.
- Chemical composition and internal structure, such as grain size or crystal structure, influence the mechanical and physical characteristics of materials.
- Product designers may use this knowledge to narrow down their options for materials for a specific application by learning about some of the most prevalent mechanical and physical qualities.
- Heat exchangers and refrigeration might benefit from metals with high thermal conductivity.
- High-temperature applications may make advantage of materials with low thermal conductivity, but many high-temperature components need materials with high thermal conductivity, making environmental knowledge essential.
- All other metalworking operations, including rolling and drawing, are made easier by the ability of the material to resist cracking or breaking.
- It is thus important to consider impact resistance when the application entails high risk of impact.
- The Yield Point is a factor in design calculations because it helps engineers determine when dimensional integrity has been compromised under stress.
- Yield strength is also measured in Newtons per square millimetre (Mega Pascals or MPa) or pounds per square inch, much as tensile strength.
- At a particular temperature, toughness is determined by performing the Charpy impact test, which is identical to the Impact Resistance test.
- Materials may become more brittle at low temperatures because of the decreased impact resistance.
- Wear resistance is a measure of this ability.
- Managing wear on the softer metal might be a design consideration when the materials have varying degrees of hardness.
- The amount of mass lost for a given number of abrasion cycles at a particular load is one way to gauge wear resistance.
- A metal's mechanical and physical qualities, when taken into account, may help in the selection process.
FAQs About Metal
Metallurgy is the science and technology of metals and alloys. The study of metallurgy can be divided into three general groups: ... Process metallurgy is concerned with the extraction of metals from their ores and the refining of metals.
Metallurgy is part of materials science and engineering that involves the study of the physical and chemical behaviour of metals. This includes metallic elements, their compounds and their alloys. ... – It is the science and study of the behaviours and properties of metals and their extraction from their ores.
The science of metallurgy is subdivided into two broad categories: chemical metallurgy and physical metallurgy. Chemical metallurgy is chiefly concerned with the reduction and oxidation of metals, and the chemical performance of metals.
The science of metallurgy is further subdivided into two broad categories: chemical metallurgy and physical metallurgy.
The three main branches of this major are physical metallurgy, extractive metallurgy, and mineral processing. Physical metallurgy deals with problem solving: you'll develop the sorts of metallic alloys needed for different types of manufacturing and construction.