Metal Strength Chart: a Basic Guide to Metal Strength You Must Know

Whether the metal is used to produce tools, construct buildings, or lay railroads, its strength is crucial in determining which metal is best suited for the task. Generally, strength varies depending on the metal and the application.

Metal strength is one of the most important mechanical properties when categorizing metal applications and usage. Some metals may be appropriate for use in the building industry but not in the aerospace industry. Understanding metal strength is critical when making a choice.

The metal strength chart is essential in assisting engineers, designers, and manufacturers choose the best metals for their projects. This article has collected a metal strength chart (including tensile strength, yield strength, hardness, and density) for your reference to help you make the best choice.

Types of Metal Strength: the Common Parameters Used

In the mechanics of materials, a material’s strength is its capacity to withstand an applied load without failing or deforming plastically. Depending on how a load is applied, materials display varying types of strength. These strengths are parameters to consider when selecting a material for a specific application. The following are the several types of metal strength:

Tensile Strength

Tensile strength is the maximum amount of tugging or stretching a metal can withstand without being irreversibly damaged. It is the measure of how much tension a metal can withstand. Suppose an external force is applied to metal and its yield point is exceeded. In that case, some of the subsequent deformations are irreversible and permanent. Tensile strength is an excellent indicator of how a metal part will perform in an application. 

Using a tensile testing machine can evaluate the tensile strength of a metal. The tensile testing machine has two wedge grips that securely grasp a metal part at opposite ends. During the testing procedure, the machine gradually pulls the part lengthwise until it breaks. The amount of tensile force (or stress) applied to the metal and elongation are measured throughout the test to determine the tensile strength of the metal part. 

The tensile strength can be further divided into three parts, including yield strength, breakable strength, and ultimate strength. The graphical representation of tensile strength below can help you understand them more intuitively:

Yield Strength

In a tensile test, yield strength is the maximum strength a metal can withstand before exhibiting permanent plastic deformation. Engineers and manufacturers calculate this value to know the maximum load a part can accommodate. Many engineering codes utilize yield strength as a criterion for defining failure.

Breakable Strength

Material strength is the point on the engineering stress-strain curve (yield stress). Beyond this point, the material suffers deformations that cannot be entirely reversed upon removal of the loading, resulting in a permanent deflection of the member. Breakable strength refers to the stress coordinate at the point of failure on the stress-strain curve (the last stress value recorded).

Ultimate Strength

Ultimate strength is the maximum tensile, compressive, or shearing stress that a certain unit area of metal can withstand without breaking or deforming. In other terms, it is the maximum value of stress that a metal can reach.

Compressive Strength

Compressive strength, as its name implies, is the maximum amount of pressure or compression a metal can withstand without being damaged. A universal testing machine is required to measure a metal’s compressive strength. This machine will progressively raise the load on the metal until it begins to distort. In this form of strength, the load is applied to the top and bottom of the specimen. The point at which deformation begins is the metal’s compressive strength. 

Impact Strength

Impact strength is a measure of how much impact or abrupt force a metal can withstand before failing. A metal’s limit and impact load are stated in terms of energy. As a result, impact strength aids in measuring the amount of energy a metal can absorb before fracturing, tearing, or destroying.

A widespread misconception in manufacturing is that high impact strength equates to increased material hardness. This is not always the case, though. Some factors may affect impact strength, such as material thickness (increase in thickness decreases impact strength), temperature (increase in temperature increases impact strength), and notch radius (reducing the notch radius lowers the impact strength).

Why is Metal Strength So Important?

The metal strength can help you determine if it is appropriate for your application. Strength is crucial because it determines whether or not a machine part will be able to serve its intended purpose. Below is a detailed explanation of why metal strength is essential in various sectors.

Mechanical And Structural Design

Engineers and designers must consider the strength of the parts when it comes to mechanical and structural elements. This consideration of strength will assist in determining the precise point at which the metal may fail or break. Thus, they can set limits and develop reasonable restrictions for specifically designed parts.

Material Selection

Metal strength is a crucial characteristic for selecting materials that can withstand the demands or needs of different industrial applications. Varying metals have different strength ratings. Some metals are ideal for high-stress applications, and others are more suitable for low-stress applications.

The structure may be readily deformed if the low-strength metal is utilized instead of the high-strength metal. For instance, the parts of a heavy-duty machine require metals of high strength. Typically, steel or titanium is the ideal option for this job.

Using a low-strength metal for a part intended for usage in a weight-lifting crane will only jeopardize the part’s integrity. This renders the product ineffective for its intended purpose and squanders the company’s time, effort, and resources.

Durability And Safety 

As previously stated, a metal’s strength is defined as its ability to withstand an applied load without failing or deforming plastically. As a result, strength determines the durability of parts created from such metals, which is especially important for parts subjected to high-stress applications.

In addition, the strength of metals aids in establishing various limitations to avoid application failure. Understanding metal strength ratings enhances the safety of the part design. You will ensure that these parts can adequately withstand the required loads without causing harm to users.

What are the Commonly used High-strength Metals?

High-strength metals are dependable for various applications, whether sourced from nature or created through laboratory design and artificial alloying processes. There will be the strongest metals in the industry that manufacturers may prefer depending on the application and design needs. The following metals have superior strength properties.

Chromium

Chromium is a hard metal distinguished by its silvery, shiny, “polished” look. It has a high melting point and a stable crystalline structure. Both 304 and 316-grade stainless steels contain at least 10% chromium by weight.

On the Mohs hardness scale, chromium metal has the highest rating, but it is brittle and must be combined with other metals to increase its tensile strength. Stainless steel is an excellent example of a metal alloy that incorporates chromium to boost its strength. Additionally, chromium is frequently used in chrome plating.

Titanium

Titanium is a naturally occurring metal with high tensile strength due to its less dense structure than common metals. Titanium’s low strength-to-weight ratio and superior corrosion resistance make it an ideal material for aerospace, automotive, medical, and military applications. In addition to its pure form, titanium is frequently alloyed with other metals to increase its strength. One example is titanium aluminide, which contains aluminum and vanadium as alloying parts.

Tungsten 

Tungsten is the strongest and toughest naturally occurring metal due to its ultimate tensile strength of 250,000 psi or 1725 MPa. Tungsten is so dense that it resists melting even at extremely high temperatures. This metal has a metallic and gray look and is typically brittle. Tungsten is frequently alloyed with other elements to compensate for its brittleness. The most popular alloy is the tungsten carbide. Tungsten’s strength is particularly beneficial for various uses in the military, aerospace, mining, and other metalworking sectors.

Carbon Steel

Carbon Steel is one of the most prevalent iron-carbon alloys, and it ranks highly in every aspect that characterizes the strength of a metal. It is among the strongest metals due to its yield strength of 260 MPa and tensile strength of 580 MPa. It also has excellent resilience to impact.

Carbon steel may be fabricated into various hardness levels by manufacturers. Typically, this relies significantly on carbon content. As carbon content increases, steel strength increases. Carbon steel is a good material for use in building and other applications.

Stainless Steel

Stainless steel is a corrosion-resistant steel alloy with steel, manganese, and chromium. It has a yield strength of around 1,560 MPa and a tensile strength of approximately 1,600 MPa. Stainless steel is very impact resistant.

One of the unique characteristics of stainless steel is its silver mirror coating. This metal is glossy and does not tarnish when exposed to air. Stainless steel is used in various applications, including cookware, metal ceramics, appliances, surgical instruments, etc.

Magnesium Alloys

Scientists are constantly developing and testing new alloys with even better characteristics. In recent years, several university research groups have unveiled new forms of magnesium alloys that demonstrate outstanding strength, lightweight, and excellent corrosion resistance. These novel materials are already employed in smartphone and laptop casings, electric batteries, and medical implants.

Inconel

Inconel is an alloy comprising austenitic nickel and chromium and additional elements such as molybdenum. These superalloys are exceptionally durable and resistant to corrosion, making them ideal for use in harsh settings and situations.

Inconel is available in numerous grades, including 600, 601, 625, 690, 718, 751, 903, and 939. These alloys are frequently used in turbine production, turbocharger rotors, heat exchangers, and pressure vessels, among others.

Iron

Iron is a good choice for rifle barrels, bicycle chains, cutting tools, etc. With a yield strength of 246 MPa and tensile strength of 414 MPa, it completes our list of the strongest metals for manufacture.

What are the Processes for Enhancing Metal Strength?

Some metals are weak and pliable in their native condition. For instance, bronze and iron are weak in their native state, but various processes may strengthen them. Following these processes, numerous industries can utilize these metals for multiple applications. Here are several processes used to enhance metal strength.

Solution Hardening

Solution hardening is one approach to producing metal alloys. Despite its complex name, the notion of solution hardening is straightforward. Manufacturers will blend one metal with another to create a strong alloy. Both metals must be in liquid form for this purpose. The high temperature permits one metal to meld with the other. However, you can only add a limited quantity of one metal to another.

Cold Working

Using a process known as cold working is another method manufacturers use to strengthen metals. Cold working alters the form of metal rather than changing its parts. In contrast to many other processes, cold working does not require heat. A metal’s crystalline structure is altered to make it stronger by applying enormous pressure during cold working. A machine will employ two rollers or tiny holes to compress and strengthen the metal. The metal gets considerably stronger and more durable after undergoing cold working, but it also becomes less ductile. Steel, copper, and aluminum are often the metals subjected to this process.

Transformation Hardening

Transformation hardening is frequently used to enhance steel’s strength. The procedure entails heating and cooling a metal, which results in the formation of microstructures inside the metal. These microstructures strengthen and harden the metal. A manufacturer does transformation hardening in three steps.

1. The initial step is known as austenitizing. In this procedure, the manufacturer will heat the metal to a critical temperature, therefore altering the metal’s molecular structure.

2. Next, the manufacturer will rapidly cool the steel. This procedure is referred to as quenching. The metal must be swiftly cooled to prevent the formation of additional materials such as pearlite and cementite throughout the process.

3. Finally, the metal is heated to a temperature ranging from 400 to 1,300℉ by the manufacturer. This procedure decreases the metal’s brittleness. The manufacturer will then allow the metal to cool gradually to make the finished product.

Precipitation Hardening

Precipitation hardening is the final process that manufacturers utilize to strengthen metals. Manufacturers will heat the metal to high temperatures to strengthen it. During this process, solid impurities occur on the metal. These impurities reinforce the metal and increase its durability by preventing the material from moving or dislocating.

What is the Difference Between Strength and Hardness？

Many people frequently use strength and hardness interchangeably because both terms describe how strong the material is. Although they are closely related, hardness varies from strength in many ways. The table below shows their differences.

Strength refers to the capacity of a material to withstand deformation produced by the external load. The more external load a material can sustain, the greater its strength. Basically, hardness is defined as a capacity of a material to resist indentation, penetration, or scratching induced by another material. Only a harder material can penetrate into a softer material.

Strength and hardness are tested in very different methods. Metal strength is assessed using a tensile or compressive test on a universal testing machine. In contrast, hardness may be determined in various ways, such as the Rockwell hardness test, Brinell hardness test, Vicker hardness test, and Shore stereoscope.

These two are crucial in the design and engineering industries since they are among the most critical properties taken into account. Strength establishes the limits for the maximum permissible load on the manufactured parts, which is essential for preventing structural and mechanical breakdowns. In contrast, the hardness of a metal is an excellent predictor of its resistance to mechanical wear. Harder metals are preferred for manufacturing parts that must be highly resistant to wear.

What is the Difference Between Strength and Stiffness？

Strength is a measure of stress a material can withstand before irreversibly deforming (yield strength) or breaking (tensile strength). If the applied stress is less than the yield strength, the material will go back to its original shape when the stress is removed. If the applied stress exceeds the yield strength, plastic or permanent deformation occurs, and the material cannot recover its original shape once the load is removed.

Stiffness is associated with how a part bends under load while still reverting to its original shape when the load is removed. Since the part’s dimensions remain identical after the load is removed, stiffness is connected with elastic deformation.

A material can have both high strength and low stiffness. A metal has low strength if it cracks quickly, but it can deflect a high load if it has low stiffness. Generally, stiffness is determined by the modulus of elasticity, also known as Young’s Modulus, which is constant for every given metal. Because steel has Young’s Modulus three times that of aluminum, an aluminum part under load will deflect three times as much as a similarly loaded steel part. The thickness and shape of the manufactured part also contribute to its stiffness.

Take a look at the table below, which shows Young’s modulus values for common materials.

Metal Strength Chart

When your project necessitates metal parts, there are several key parameters you should understand about common metals—yield and tensile strength, density and hardness, etc. The metal strength chart below can be used to compare and refer to the properties of different metals.

Conclusion

Before selecting a metal material for your project, you must know what the metal is used for and the loads it can withstand. So, you may need to do some engineering calculations to identify which metal has the strength you need.

Strength is an essential property in metal applications, especially in building, transportation, heavy industries, and toolmaking industries. Some applications demand stronger aluminum parts, while others require high steel hardness or yield strength of steel. 

You can use the metal strength chart to select an appropriate metal material based on your project’s characteristics, functions, and applications. Besides, if you are not sure which material is best for your project, you can contact LEADRP anytime. LEADRP has rich experience in CNC machining and offers professional DFMs and suggestions for your project.