Annealing is a heat treatment process where a metal is heated to a predetermined temperature and then cooled at a specific rate. During the annealing process, the metal undergoes physical and (sometimes) chemical changes that improve its ductility and reduce hardness.

The Stages of Annealing

As previously mentioned, annealing is a heat treatment method that increases the ductility of soft metals (steel, copper, brass, etc.). When these metals experience hardening, they lose their ductility and certain mechanical properties. The annealing process helps to enhance the metal’s original properties.

There are three primary stages within the annealing heat treatment process: recovery, recrystallization, and grain growth.

1. Recovery Stage

This initial stage is marked by heating the metal in an industrial furnace to a temperature that relieves the metal’s internal stress by removing dislocations (defects). During this initial stage, the metal is softened, and some of its original properties are recovered.

2. Recrystallization Stage

The second stage is called the recrystallization stage because the metal is heated below its melting temperature but above its recrystallization temperature. This initiates the formation of new stress-free grains that replace deformed grains of the metal’s crystal lattice structure.

3. Grain Growth Stage

During this final stage, the metal undergoes controlled cooling, which enables new grain growth. The metal is sometimes left inside the furnace and gradually cooled or placed in heat-conductive materials (sand). This final stage completely changes the metal’s microstructure, resulting in more ductility and lower hardness values.

Why Is Annealing Important?

The primary purpose of annealing is to undo some of the effects of work hardening, which can occur accidentally during some metal formation and fabrication processes. By undoing these effects, the metal’s overall hardness is reduced, which is important because the hardness of a metal will impact its workability. 

For example, if a complex part needs to be created from metal, that metal needs to be ductile to prevent cracking during the formation process.

Industrial Uses for Annealed Metal

Exceptionally ductile metals can withstand high-impact loads without breaking or fracturing, which is largely why the automotive industry is such a heavy user of annealed metals.

The construction industry is also heavily-dependant on annealed metals, as are manufacturers that need workable metal to create complex parts. 

The aerospace industry uses annealing to improve aluminum’s workability and eliminate the effects of strain hardening in aluminum. When aluminum has experienced repeated plastic deformation, its hardness increases and requires annealing to relieve its internal stresses.

Welding applications also benefit from annealed metals, as annealing helps reduce stresses that occur during the welding process.

Lastly, sheet metal fabricators may utilize annealing, as steel sheet fabrication processes can result in a material with too much hardness.

Learn More About Annealing Today

SST has been an innovator and leader in precision-controlled heat treatments since 1956. For over 60 years, we’ve adopted a customer-first mindset in multiple industries and markets, including aerospace, automotive, and heavy equipment. We’re also backed by multiple industry accreditations and certifications.

Please contact us today with general questions about annealing or to learn more about our heat treatment processes and capabilities.

You may have seen the words “heat treated” in relation to steel products like knives, hand tools, and other works of steel. But what exactly does the term “heat treated” really mean? Heat Treatment consists of heating up metal to at or above a predetermined critical temperature and then cooling it down. This extreme heating will change certain chemistry within the alloy and the cooling down process will set those changes within the alloy permanently. We’ll look at the different types of heat treatment for metal alloys below.

Annealing

Annealing is widely used and one of the most popular heat treatments around for metal alloys. The typical procedure for annealing is to put the metal into a walk-in furnace or hot room in the plant. The metal’s temperature will rise to a reading around 50°C above critical at a steady rate. Once the metal has reached this point for a set period of time (2-3 hours) the metal will then cool slowly back to its normal range.

This cooling down procedure is done by stepping the hot room temperature down little by little over a range of time. Think of a heater’s thermostat that kicks on and off due to the air temperature. In the case of annealing, this thermostat will slowly drop in temperature until the final cooldown temperature is reached. This process will “soften” the steel to make it more malleable for machine work.

This process will also remove any gases that remain in the steel’s composition, thereby strengthening the steel. Another benefit to annealing is that it will magnify the metal’s magnetic and electrical properties which is ideal for powder coat and other electrical paint mediums.

Normalizing

Normalizing has some similarities with Annealing as they both rise to the same 50°C above critical threshold. The major difference with Normalizing is that the holding time at that temperature is much less than with Annealing. The cool down process is also much quicker as the metal is transferred out of the hot room back into the open plant to air dry at normal ambient temperatures (room temperature).

This cool down process (or air quenching) will forge the changes made at the heat point made earlier. Normalizing relieves any stresses within the metal and is typically done to cold-worked steel such as stamped, hammered, or rolled steel.

Hardening

Hardening is the process of toughing up the steel to make it harder and less brittle. If Annealing is the “Yin”, Hardening is the “Yang” as it’s the exact opposite of Annealing in terms of heat treatment. If you’ve ever seen a blacksmith make a sword or a knife, you’ve seen Hardening in action as it’s an important part of the process.

The metal is heated to 40°C above critical temperature and then rapidly cooled by placing it in oil or water. Sometimes, a brine solution is used in place of water as water can sometimes cause bubbles to form on the metal’s surface. You can see the end results of hardening in objects such as the aforementioned knives and swords and also gears, taps, dies, and chisels.

Tempering

Hardening can cause metal to become brittle in places depending on the thickness of the metal being hardened. The typical next step when using the Hardening method to heat treat thin metals such as blades is to temper it. Tempering will reduce the brittleness of the metal by removing internal stresses on the metal that developed during the Hardening process.

The usual process for tempering metal is to take the freshly hardened piece and reheat the metal back up. This heating point is usually at a range between ambient temperature and critical point temperature. This temperature could reach as high as 700°C and once this temperature is reached, the metal will stay ensconced for a period of time. Tempering is typically done in an oil bath or molten lead bath and the holding time at top heat is based upon the type of metal used and the desire of hardness in the metal.

Nitriding

Nitriding is the process of forming a thick “skin” on the surface of the metal and this is typically done by utilizing nitrogen gas, hence the name “nitrding”. This type of heat treatment is perfect for those who don’t want the entire metal piece to be hardened and just want the surface toughened up. This method is sometimes used for tools that typically see a lot of dings and scratches over time such as wrenches.

The process for nitriding is to place the metal in an airtight chamber of which there are tubes feeding into the chamber. The tubes are inlet and outlet for ammonia gas which will circulate inside the chamber. The chamber is heated up in a furnace reaching 500°C which will cause nitrogen gas to be released from the circulating ammonia inside the chamber. The nitrogen gas will form atomic nitrogen due to the heat and this will cause a chemical reaction with the metal, forming iron nitrate on the surface.

The longer the metal is at this iron nitrate state at elevated temperatures, the deeper the iron nitrate will penetrate the metal. Once the process is completed, there is no cool down or quenching needed as the iron nitrate will be permanently bonded to the metal.

Cyaniding

Cyaniding is a heat treatment method for small to medium-sized pieces of metal which will strengthen the metal’s fatigue point and limit. This heat treatment method will also raise the surface hardness of the metal. The name “cyaniding” is derived from the sodium cyanide that is used in the heat treatment process.

The process for cyaniding starts with the metal being placed in a molten cyanide salt bath at a temperature of 950°C. The molten salt bath consists of sodium cyanide, soda ash, sodium carbonate, and sodium chloride. The metal is kept in this molten bath for around 20 minutes as the sodium cyanide will break down in the heated environment. This chemical breakdown will cause nitrogen to form as well as carbon from the carbon monoxide. The nitrogen and carbon will seep into the metal’s surface causing it to harden during the process.

Once this process is completed after 20 minutes, the metal is taken out of the molten bath and then quenched in either an oil or water bath to cool the metal down and completing the hardening process.

SST for Heat Treating

Specialty Steel Treating Inc. has been in the steel heat treatment game for over 60 years. We have provided steel heat treatment services for industries such as industrial, rail, heavy equipment, automotive, tool and die, and aerospace. If you’d like to know more about our steel heat treatment services, please contact SST today!

Are you looking for a way to increase the durability and longevity of your metal? If so, you might be curious about heat treatment. Heat treatment is a process that can be applied across multiple industries, so this may be a strong choice for you as well.

During this process, a metal or alloy is altered by multiple heating and cooling cycles. Usually, there are complex thermal boundary conditions that are spread across wide temperature ranges. This is a process that can be applied to cast iron, stainless steel, magnesium, aluminum, and numerous other materials.

What are a few examples of applications of this process? Take a look below, and rely on heat treating companies MI to help you.

The Automotive Industry

One of the most common applications of heat treating metals is in the automotive industry. Whether you are working with aluminum, titanium, or iron, you need to make sure that you use firm material that leads to durable vehicles. Regardless of whether you are producing commercial vehicles or consumer vehicles, make sure your vehicles are up to the task. We can help you make sure your metal is ready for the stress of routine wear and tear.

The Aerospace Industry

Heat treating is also commonly used in the aerospace industry. Commercial jets undergo a significant amount of stress when they take off and rise to 30000 ft. There is even more stress involved if a vehicle or satellite goes into space. You need to make sure the metal is going to stand up to this type of stress, which is why heat treating is helpful. Furthermore, heat treating can make the metal more pliable, allowing you to meet your needs. If you need to produce products for the aerospace industry, you may want to use heat treating to help you.

Industrial Equipment

This type of process is also commonly used in the production of industrial equipment. There are countless industries that rely on heavy machinery every day, and there are numerous parts that have to work together in perfect harmony for these complex machines to function appropriately. There are plenty of types of metals that are used in heavy machinery including iron, steel, and even titanium. You need your industrial equipment to be strong and durable, and this is another area where heat treating can be helpful. If you want your computers to be durable, reliable, and efficient, this may be a process you want to explore.

Firearms

Finally, even firearms are dependent on the heat-treating process. There are small, precise shapes that have to be made for firearms to work effectively. The heat-treating process makes it easier to add small grooves to the firearms, yielding the attention to detail that firearms require. No matter how big or small the firearm might be, this type of metal is a necessity. It also allows the firearm to stand up to routine wear and tear. If you want your equipment to stand up to routine use, you need to work with a team that can help you with heat treating.

Count on Specialty Steel Treating for Heat Treating Companies MI

These are just a few of the many industries in which heat treating might be helpful. If you want to get the most out of your metals and alloys, you need to work with a company that can help you with heat treatment. That is where we can assist you. We are Specialty Steel Treating, and we have a tremendous amount of experience working with a wide variety of materials across multiple industries. It would be our pleasure to assist you as well. If you are looking for the best heat treating company MI, contact us today!

Are you looking for a way to get the most out of your materials? Do you want your metals and alloys to work as well as possible? If so, then you may have heard that heat treating can be beneficial. This is a term that is used to refer to putting metals and alloys through multiple heating and cooling cycles. This is a process that can change, modify, or enhance the individual properties of certain materials. That way, you can get the most out of it. You may not be used to heat treating your metals, but there are a number of benefits you might enjoy. Take a look at a few of the top benefits below. Remember to work with the best heat treating companies MI to meet your needs.

Increased Versatility

One of the first benefits of this process is increased versatility. This is sometimes called increased workability or increased machinability. Essentially, this process can remove a lot of internal stresses from prior fabrication processes. This includes welding, stamping, and machining. If your metal is too hard to bend or alter, you can anneal it using the heat-treating process. Then, it will be easier to work with. If you need to make your material more pliable, then you may want to check out the heat-treating process.

Increased Durability

Furthermore, this is a process that can make your metal more durable. As it goes through multiple cycles, the material will become harder. Examples of common materials that can be hardened using this process include titanium, steel, and copper. This makes it easier for the metal to stand up to routine wear and tear. Furthermore, if you have inexpensive steel, this is a process that may be able to increase its lifespan. If you want your material to be as durable as possible, then you may want to take advantage of the heat-treating process.

Increased Toughness and Strength

Furthermore, this is a process that can help you increase the toughness and strength of the material. There is always a trade-off, as the material can become brittle if it becomes too tough, but you also have a significant amount of control regarding how many cycles you put the material through. There may be some situations where case hardening can be beneficial. It can help you temper the material, draw it back to its original properties, and reduce its brittleness. If you want to make sure you get this process right, you should work with professionals who can walk with you during each cycle.

Increased Magnetic Properties

If you need to increase the magnetic properties of the material with which you are working, this is a process that can help you. It is not unusual for materials to gain magnetic properties, which is usually referred to as their magnetic permeability. If they are work hardened, you can increase the magnetism of each individual metal. At the same time, if you would like to reduce the magnetic properties, there are specific and kneeling processes that can help you. You simply need to work with a team that has experience in this area so you can be placed in the best position possible to be successful.

Increased Longevity

Finally, if you decide to go through the heat-treating process, you can also increase the longevity of the materials with which you are working. No matter what industry in which you are operating, your materials are going to go through a significant amount of wear and tear. You do not want your equipment to break too soon, as this can lead to a significant repair bill. You can increase the longevity of your metals if you decide to go through the heat-treating process.

Work With Specialty Steel Treating for All Heat Treating Needs

If you are looking for the best heat treating companies MI, then look no further than Specialty Steel Treating. We have connections with some of the top providers in the industry. This means that we can help you access some of the best equipment and materials at the lowest price. Furthermore, we can put our skills to work for you, making sure you get the most out of your metals and alloys. Our top priority is to make sure that we meet or exceed your expectations every time. If you would like to learn more about how we can help you, please contact us today. We look forward to hearing from you.

Before steel products are ready for application, they need to be treated with heat to increase their strength. Learn about how our professionals at Specialty Steel Treating handle the quenching, or cooling, process and what types of media are used for different applications and products. 

Different Media for Quenching Steel

Most manufacturers use oil as the medium for steel quenching process. There are many kinds of oil, allowing for the process to be modified to suit the type of steel and treatment requirements. For example, when treating steel with a low carbon content, using a fast oil, or one that cools quickly, is better than using a slow oil, or one that stays hot for long periods of time. Additionally, oil boils slowly, so the treated steel has longer to adjust to the heating process.

Some of our clients prefer to use gas for the steel quenching process if they need to maintain an exact cooling rate or prevent their parts from getting dirty. Gas quenching always takes place in a vacuum and usually involves nonflammable nitrogen, but argon and helium are also possibilities. This medium is ideal for steel that cannot risk the distortion that is possible with oil quenching but still needs to be extremely hard.

The simplest and cheapest version of quenching uses air as its medium. The most precise form of air quenching involves blowing compressed air onto heated steel until it has cooled to the right degree. This process can involve simply heating steel and letting it cool in a normal environment, though. Air quenching is only possible if the steel equipment does not need to become drastically harder because its cooling process is so uncontrolled.

Choosing the right medium depends on the carbon content of the steel in question, its desired softness, its cost, and the amount of time available. For example, vacuum quenching is expensive, but it may be necessary for a hyper-controlled cooling process.

Steel Quenching Process

Regardless of the medium used to cool steel, all quenching processes begin with the application of heat. First, the steel is heated until it’s hotter than its upper critical temperature, which is between 1333 and 1670 degrees Fahrenheit. Then, the piece is moved to the quenching medium, whether that is an oil bath, water tank, or gas vacuum chamber.

The temperature of the cooling medium depends on how hard the finished product should be. Generally, the more quickly a batch of steel is cooled, the more severe the quench is and the harder the steel becomes. For example, to make steel with a high concentration of alloys slightly harder, we use a medium that isn’t very severe. A high-temperature oil bath is a good option.

There are several major safety concerns when completing the steel quenching process, so it must be completed carefully and with proper personal protective equipment. First, because it involves using steel that has been heated to very high temperatures, the chances of burns and equipment breakdowns increase. Secondly, using oil as a quenching agent increases the risk of a fire, particularly if some of the hot oil spills during the work. Finally, while some of the other options for quenching are not flammable, they can pose health risks to workers, including melted salt and caustic liquids.   

Work with SST today!

Although steel quenching can be a dangerous process, it’s necessary for making sure steel is strong enough for use in manufacturing, medicine, construction, and research. By choosing the proper cooling medium and handling the process carefully and safely, Specialty Steel Treating produces heat-treated steel that has the proper hardness and carbon content for its designated purpose.

Heat treating metals is a critical step in the manufacturing process. Whether you’re creating finished products for the end user or preparing materials for a manufacturer, explore these four key solutions and how they can improve the mechanical features of your metal.

Heat Treating Metals

While there are several distinct methods for heat treating metals, they all use the same basic features. Heat treating uses specific temperatures applied at specific amounts of time before being cooled.

All three variables are altered to achieve different results. Consider the results you need, as well as the materials you’re treating, before you choose the best treatment for your process.

4 Heat Treatment Solutions

Alter your metal to prepare for precision machining. These four methods for heat treating metals are capable of delivering the results your process needs:

1. Annealing
2. Normalizing
3. Hardening
4. Tempering

Annealing

Choose steel, aluminum, silver or your desired ferrous metal that requires high levels of ductility. Annealing brings the temperature up slowly, then soaks the material. A slow cooling process occurs to gradually bring the metal down to room temperature.

This process uses a more gradual cooling method than normalizing. The part is cooled in an insulated material or in the furnace itself, rather than being removed and cooled by air.

Enjoy a more formable material for less risk of fracturing during the fabrication process. This is a common process to remove residual stress from metals that have been cut or processed before the heat treatment.

Normalizing

Higher levels of heat and more rapid cooling creates a normalized part. Similar to annealing, normalizing offers a machinable, ductile component that’s still strong enough for many applications in various industries.

To start, the material is heated gradually. The temperature is approximately 150 to 200 degrees Fahrenheit higher than the range used for annealing. This higher temperature is held for long enough to transform the grain structure of the metal.

Smaller austenitic grains that are created during the heat process are transformed to refined ferritic grains after the air cooling process. Air cooling relies on the mass of the material to determine the cooling time. This means that thick and thin parts will have differing characteristics as a result of the normalizing process, which isn’t necessarily the case with annealing.

Hardening

Create strong, hard steel through hardening. This process of heat treating metals takes three stages. The first two stages are typical of heat treatments, slow heating and soaking. Unlike normalizing or annealing, however, hardening uses a rapid cooling process. A plunge into water, brine or oil, known as quenching, helps produce some of the more unique characteristics of hardened metal.

First, this creates a particularly hard and strong metal. There are several alloys you can add to further increase its hardness. A material this hard is also brittle, so it isn’t as ductile or machinable as other heat treated metals.

Tempering

Choose tempering to balance some of the more extreme characteristics of hardening. This step in heat treating metals typically only occurs after the metal is already hardened. Tempering reduces brittleness and hardness in hardened metal.

The result is less internal stress and a more machinable product. In many cases, hardened metal is too hard and too brittle to be suitable for use in your industry. Tempering complements hardening to achieve the material you need for your products.

The process starts by reheated hardened material. At 212 degrees Fahrenheit, the tempering process begins. It continues until your material reaches the optimal hardness and strength. The cooling rate isn’t as important in tempering as it is in annealing or normalizing, but tempered materials are typically removed from the furnace and air cooled.

Explore the furnace brazing to see how you can create cost-effective, reproducible products from multiple metal components. Review the steps required to perform this semi-automated process and how you can improve your manufacturing capabilities. After following the steps of the process, you can see the benefits and common applications of this metallurgical technique.

Furnace/Vacuum Brazing

The furnace brazing process is used to join simple or complex metal components using a dissimilar filler metal. It’s used in a range of markets and applications for a firm, secure joint.

Choose brazing if you need a leak-free joint, lightweight assembly and cost-effective solution. Use the process for stainless steels, nickel-based alloys, carbon and alloy steels, etc.

The Brazing Process

The process requires a braze material with a lower melting temperature than the components to be joined. First, the components need to be thoroughly cleaned to prepare for the process. Then the braze alloy needs to be applied between the components. The parent alloy parts need to fit closely and be fixtures into place to ensure an accurate process.

The parent alloys don’t need to be weldable, similar materials or even metallic. Brazing can be used to join a wide range of dissimilar or similar materials with a solid, void-free joint.

Next, the braze is heated between the components. There are different types of furnace brazing, but vacuum brazing is the most common. This process occurs in a vacuum furnace.

The precise temperature varies depending on the braze and parent alloys. It must be hot enough to melt the braze alloy, but not the parent alloy.

Oxidation is a serious risk in other types of brazing, but vacuum brazing eliminates this risk. It also makes flux unnecessary for the process.

Capillary action creates a strong seal by completely filling the gaps between the two or more parent components. The result is a one-piece construction with uniform thermal conductivity and strength.

Benefits of Furnace Brazing

This popular furnace brazing process comes with many distinct benefits. Here are the benefits of this metallurgical technique:

• Improved mechanical strength
• Uniform thermal conductivity
• Void-free joints
• High proof pressure
• Clean, consistent finish

You don’t have to worry about surface deterioration or excessive distortion when you use vacuum brazing. Compared to dip brazing, the process is extremely clean. The flux-free process means no corrosive flux needs to be cleaned from your parts.

The result is a highly affordable process that creates metal components with high levels of integrity. Engineers can use this joining solution for a single, basic joint or a complex design with multiple, hidden joints. It’s also usable in situations where the parent allows are unweldable or dissimilar.

Common Applications of Furnace/Vacuum Brazing

Virtually any application that requires a strong, void-free joint of similar or dissimilar materials can use furnace brazing. Here are the most common industries that use this process:

• Aerospace
• Electronics
• Energy
• Medical
• Scientific
• Automotive

While not limited to these industries, there are some areas where the features of brazing can give you the results you need. This metallurgical technique isn’t suited for every application, but it can be used to create simple or complex components that are durable and reliable.