Ultimate Guide to Melting Points of Metals

Introduction

Did you know? In the field of metal processing and metal application, common metal failure problems such as degradation of metal mechanical properties, high temperature oxidation, thermal fatigue, etc. caused by high temperature working conditions will greatly shorten the life of equipment and bring serious safety hazards. One of the key reasons for these problems is the melting point of metals. Knowing the approximate melting point of each metal and alloy is of great significance for us to choose the appropriate metal processing method and formulate solutions that take into account cost-effectiveness and project performance requirements according to specific applications.

This guide will explore the importance of metal melting points from multiple perspectives, the multiple factors that affect melting points, and will also provide some suggestions for metal material selection in different application scenarios. I hope this article can provide you with new perspectives and thoughts.

Note: The melting point data provided in this article are taken from Wikipedia and are for reference only. Each alloy type contains multiple alloy grades, and the specific melting points may vary. In order to obtain accurate data, it is recommended to conduct actual inspections and consult professional technicians.

What Is the Melting Point?

The melting point of a metal refers to the temperature at which the solid metal gradually changes from a completely solid state to a solid-liquid coexistence state under standard atmospheric pressure.

Why Are Metal Melting Points Important?

The melting point of a metal is one of its basic properties. In many industrial safety and industrial production, it is important to understand and think about the melting point of a metal.

Smelting and Casting

This is the most basic meaning of the melting point of a metal for industrial production. The melting point of a metal is an important indicator for smelting metal raw materials. In the process of metal smelting, the metal needs to be heated above its melting point to transform it from solid to liquid for subsequent molding processing;

Select Materials According to Project Requirements

In the process of engineering design and manufacturing, the melting point of a metal is one of the important bases for metal selection. In applications such as high-temperature structural components in aerospace, nuclear reactors in the energy industry, etc., which need to maintain structural stability and mechanical properties at extremely high temperatures and avoid melting of the main structure, we will choose metals with higher melting points;

Welding and Heat Treatment

The melting point of a metal determines the temperature requirements during the heat treatment process, as well as what welding process and welding equipment we use for welding operations. For example, when we weld aluminum alloys, because the melting point is relatively low, we can choose to use TIG welding, a process that can accurately control heat, for welding. In contrast, stainless steel has a much higher melting point, so we will choose to use MIG welding, a welding process that can provide higher heat output;

Thermal Expansion and Strength

Take the thermal processing of steel as an example. We will find that when the steel is heated to near the melting point, the surface of the steel will expand and soften. This intuitive phenomenon shows that the physical properties of the steel, such as strength, hardness, and plasticity, have undergone significant changes. Understanding the melting point of metals helps us to more accurately control the process, select more suitable heat treatment processes and temperatures, so that the mechanical properties of the produced metal products are more in line with expectations and avoid material waste;

Scientific Research and Alloy Design

In the research of ultra-high temperature metal materials, in order to enable aircraft engine parts and gas turbines to operate normally under extreme high temperatures and avoid melting or degradation of mechanical properties, we will choose to add high melting point metal elements, such as tungsten, molybdenum, chromium, etc., when manufacturing these facilities and parts that need to withstand extreme high temperatures. In contrast, in some applications, metal materials with lower melting points can greatly reduce project operating costs for us. For example, when welding or electronic packaging, some metals can melt at lower temperatures (such as lead-tin alloys) and quickly form a strong connection, which can significantly reduce the difficulty of welding operations and equipment costs.

Melting Point of Common Pure Metals Chart

Note: A table of all metal melting points will be attached at the end of the article

Melting Point of Common Alloys

In the above pure metal chart, iron, aluminum, copper, potassium, sodium, and magnesium are more common in industry and are also metals with larger reserves in nature. However, in many applications, because the strength, corrosion resistance, high temperature and high pressure resistance and other properties of common pure metals do not meet the project requirements, we usually do not use pure metals as raw materials for production. We usually mix other metal elements with excellent properties with these conventional metal elements to obtain alloys to meet our project needs. Therefore, understanding the approximate melting point range of these common alloys is also important for our project material selection, heat treatment, etc. In this section, we will discuss the melting point range and application of some common alloys.

Iron and Iron Alloys

The melting point of pure iron is 1538℃(2800℉). The alloyed product of iron is the steel we are familiar with. By adding carbon, manganese, chromium, nickel and other elements, steel can further obtain better performance, while the melting point of steel is also changing.

Carbon Steel:

It is an alloy of iron and carbon, with a carbon content of about 0.05% to 2.1%. The melting point of ferroalloys gradually decreases with the addition of carbon.

Stainless steel

Stainless steel is an iron alloy made by mixing iron with a certain amount of chromium, and also contains other alloying elements such as carbon, molybdenum, and nickel (these elements are relatively small relative to the content of chromium). The melting point of stainless steel ranges from 1,375°C to 1530°C (2507°F to 2786°F). Stainless steel has excellent strength, corrosion resistance and cleanliness.

Aluminum and Aluminum Alloys

Aluminum is a widely used light metal with a good strength-to-weight ratio. The melting point of aluminum is 660°C (1220°F). By adding elements such as copper, zinc, magnesium, silicon, and manganese, aluminum alloys can have excellent corrosion resistance and strength, so they can be used in high-end manufacturing industries such as aerospace and automobile manufacturing. However, the melting point of aluminum alloys will also be affected by these alloying elements. The following are some melting point data of common aluminum alloys for reference only.

Copper and Copper Alloys

The melting point of copper is 1084.62℃ (1984.32℉). By mixing copper with zinc, tin, aluminum, silicon, nickel and other elements, we get copper alloys such as brass, phosphor bronze, aluminum bronzes, silicon bronzes and cupronickel (or nickel silvers). Copper reserves are huge, the cost is relatively low, and it has good electrical and thermal conductivity, so copper alloys can be widely used in our lives. The following are common copper alloys and their melting point ranges:

Titanium and Titanium Alloys

Titanium is strong and lightweight. It is a metal with a higher strength-to-weight ratio than aluminum, with a melting point of about 1688°C (3034°F). Titanium alloys are mainly made by mixing titanium with metal elements such as aluminum, vanadium, tin, zirconium, and molybdenum, and are widely used in various high-end manufacturing industries. The following are the common titanium alloys, with the corresponding melting point ranges:

Nickel and Nickel Alloys

The melting point of nickel is 1455℃ (2651℉). Nickel alloy is an alloy made of nickel as the main element, mixed with chromium, iron, copper, molybdenum, aluminum and other elements. It has excellent high temperature resistance, oxidation resistance, corrosion resistance and mechanical properties, and is mainly used in chemical, energy, marine and other fields. The following shows some common nickel alloy types and melting point reference ranges:

Factors that Affect the Melting Points of Metals

The melting point of metals is affected by a variety of factors, from microscopic atomic structure to macroscopic external forces. Understanding the factors that affect the melting point of metals and alloys can help us accurately control the melting point of materials and ensure that the materials can perform well in high-temperature environments. The following will explore these factors in detail, hoping to provide some thoughts for your problem.

Metallic Bond Strength

The strength of the metal bond is one of the main factors affecting the melting point of metal elements. Metal atoms attract each other through metallic bonds, forming a stable and strong structure. The stronger the metallic bond, the stronger the mutual attraction between the metal atoms, and the more stable the structure. Therefore, the energy required to destroy the metal lattice is higher, and the heat energy required to melt the metal is higher. Therefore, the melting point is proportional to the strength of the metallic bond. Simply put, the stronger the metallic bond, the higher the melting point of the metal element.

The strength of the metallic bond is affected by the following factors:

Metal Ion Charge

High oxidation state metal ions have a stronger positive charge attraction than low valence state metal ions, so the metallic bond is stronger and the melting point is higher.

Take aluminum ions and iron ions as examples. They are both trivalent metal ions, which have stronger positive charge attraction than sodium ions and potassium ions, two monovalent metal ions. Therefore, the melting points of aluminum (660.32℃/1220.58℉) and iron (1538℃/2800℉) are much higher than those of sodium (97.794℃/208.029℉) and potassium (63.5℃/146.3℉).

Atomic Radius

The smaller the atomic radius, the smaller the distance between two adjacent metal atoms, the stronger the metal bond, and the higher the melting point.

Take lithium and sodium as examples. The atomic number of lithium is 3, and the atomic number of sodium is 11. They belong to the second period (lithium) and the third period (sodium) of the same main group respectively. Generally speaking, the larger the period, the larger the atomic radius. Therefore, the atomic radius of lithium is smaller than that of sodium, and the metal bond of lithium is stronger than that of sodium. The melting point of lithium (180.5℃/ 356.9℉) is higher than that of sodium (97.794℃/ 208.029℉).

Crystal Structure

From a microscopic perspective, metals are actually composed of countless metal atoms tightly and regularly arranged in a spatial grid, so metals can also be called crystalline materials. Metal atoms are arranged in several specific spatial structures, which is the crystal structure we are going to explain here. There are three main types of metal crystal structures, and their unique crystal spatial structures lead to their different metal bond strengths, which in turn affect their respective melting points.

Body-Centered Cubic（BCC）

Structural description: In the BCC structure, atoms are located at the eight corners and the center of the cube. One atom at each corner is shared with eight adjacent unit cells. Therefore, the actual number of atoms contained in each unit cell in the BCC structure is 8×1/8+1=2. The spatial stacking efficiency is 68%. In the BCC structure, each atom has only a small number of neighboring atoms. Compared with the FCC and HCP structures, the atomic distance is relatively large, and the metal atoms are arranged more loosely, so the strength of the metal bond is weaker. Hence, the melting point of metals in the general BCC structure is relatively low.

Metals with BCC crystal structure include sodium (97.794℃/ 208.029℉), potassium (63.5℃/ 146.3℉), Cesium (28.5℃/ 83.3℉), etc.

Face-Centered Cubic Structure (FCC)

Structural description: In the FCC structure, metal atoms are arranged at the eight corners of the unit cell and the center of each face. One atom at each corner is shared by 8 adjacent units, and one atom at the center of each face is shared by 2 units. Therefore, the actual number of atoms contained in each unit cell of the FCC structure is 8×1/8+6×1/2=4. The spatial stacking efficiency of the FCC structure is higher than that of the BCC structure, which is 74%. Therefore, the metal atoms in the FCC structure are arranged very closely, the interaction between atoms is strong, and the metal bond strength of the FCC structure is higher than that of the BCC structure. Therefore, the metal elements of the FCC structure generally have a higher melting point.

Metal elements such as aluminum (660.32℃/1220.58℉), copper (1084.62℃/1984.32℉), gold (1064.18℃/1947.52℉), and silver (961.78℃/1763.2℉) belong to the FCC structure.

Hexagonal Close-Packed (HCP)

Structural description: In the HCP structure, it is mainly composed of two layers of hexagonally arranged atoms, with 3 atoms in the middle, and the atoms at each corner are shared by 6 adjacent unit cells. Therefore, in the HCP structure, the actual number of atoms in each unit cell is 12×1/6+3=5. HCP is similar to the FCC structure, both of which have a high spatial stacking efficiency of 74%, and the atoms are closely arranged and the intervals are small. Therefore, HCP structure metals also have a high metal bond strength, so the melting point is generally relatively high.

Metals such as magnesium (650℃/ 1202℉), titanium (1668℃/ 3034℉), and zinc (419.53℃/ 787.15℉) all belong to the HCP structure.

Note: FCC and HCP metals generally show higher melting points. Their most intuitive differences are mainly reflected in their ductility and plasticity, but they are not related to the topic of this article, so they will not be discussed in detail in this part.

Electronic Structure

In the above discussion, you may find that according to the crystal structure and metal bond strength theory, chromium metal, as a metal element with a BCC structure, should have a lower melting point, but the melting point of chromium also reaches a higher temperature, namely 1907℃ (3465℉). Why is this?

First of all, it is emphasized again that the melting point of a metal is affected by multiple factors at the same time. In addition to the crystal structure and atomic radius, the arrangement structure of electrons also affects the melting point of the metal.

Let’s take chromium as an example. As a transition metal, the d-orbital electrons in its electronic structure make the metal bond strength of chromium, a transition metal, higher than the metal bond dominated by only s-orbital electrons (such as sodium, potassium, cesium, etc., which are BCC structure metal elements).

In addition to d-orbital electrons and s-orbital electrons, there are also p-orbital electrons and f-orbital electrons. Generally speaking:

S orbital electrons are spherically distributed close to the nucleus, can provide strong interaction, and dominate the formation of metal bonds;

P orbital electrons are dumbbell-shaped and directional, and usually do not directly dominate the formation of metal bonds;

D orbital electrons provide weaker interaction strength than s orbital electrons, but they can significantly enhance the strength of metal bonds of transition metals;

F orbital electrons have a more complex distribution shape, provide the weakest interaction, and mainly participate in special chemical reactions.

Common transition metals containing d orbital electrons include titanium (1668℃/3034℉), vanadium (1910℃/3470℉), manganese (1246℃/2275℉), iron (1538℃/2800℉), nickel (1455℃/2651℉), copper (1084.62℃/1984.32℉), etc. They all have high melting points.

Alloy Composition and Impurity Composition

In alloys, the interaction between metal elements becomes complicated. The addition of new elements changes the crystal structure and bonding characteristics of the original main metal, and these changes also affect the melting point of the final alloy. This section will use iron and iron alloys as examples to explain the effects of alloy composition and impurity addition on the melting point of alloys.

Carbon steel

Carbon steel is mainly an alloy of iron mixed with a small amount of carbon. The size of carbon atoms is much smaller than that of iron atoms, so carbon atoms can easily enter the crystal spacing of iron, causing the crystal distortion of iron. This crystal distortion reduces the strength of the metallic bonds between iron atoms, and also makes the melting point of carbon steel (1425℃-1540℃) lower than that of pure iron, making it easier to perform hot processing, and by controlling the carbon content, the hardness and strength of carbon steel can be adjusted according to the application.

Stainless steel

Stainless steel is mainly an alloy of iron mixed with chromium and other small amounts of alloying elements. Similar to carbon steel, an iron-carbon alloy, the melting point of stainless steel (1375 – 1530°C) is also lower than that of pure iron. When the chromium content is less than 12%, the melting point of stainless steel is close to that of carbon steel. When the chromium content is increased to more than 12%, the melting point of stainless steel will be further increased.

Conclusion

In short, the melting point of a metal is the temperature at which solid metal transforms into a solid-liquid coexistence state.

Understanding the melting points of metals and alloys, and selecting appropriate metal materials or formulating material solutions according to their own applications, is an eternal topic for traditional industrial production and cutting-edge innovation. HYT is confident that this article can help newcomers and industry insiders.

HYT is at the forefront of knowledge and application, providing professional technical services and high-quality metal products, and providing the most suitable metal material solutions according to your project needs. The metal raw materials selected by our company are all from reliable domestic suppliers, which can effectively help you solve the high temperature challenges in your project. If there are high-temperature material problems in your project that need to be solved, we are willing to provide you with solutions. Please contact HYT’s technical team.

FAQ

Q: Which metal element has the highest melting point?

A: Currently, the metal with the highest melting point is tungsten, with a melting point of 3422℃ (6192℉). Because of its extremely high melting point, tungsten is used as a heating element for high-temperature furnaces and melting furnaces in the field of industrial smelting and metal processing, as an electrode and contact material in the electronics industry, and used in the production of nozzles and high-temperature components in the aerospace field.

Q: Which metal element has the lowest melting point?

A: Among many metals, mercury has the lowest melting point among metal elements, with a silvery-white liquid state at room temperature of only -38.829℃ (-37.8922℉). The most well-known application of mercury is thermometers. Due to the expansion characteristics and liquid state of mercury, temperature changes can be quickly reflected in the glass tube.

Appendix

Comprehensive Table of Melting Point of Metals

This table is arranged in ascending order of Kelvin temperature, and the elements in bold font are more common metallic elements.