Not all metals are created equal. Some are softer and more malleable, while others are much stronger and more durable. When working with steel parts, it’s fairly commonplace to treat the metal in order to create the perfect mixture of durability and strength for that part’s intended use.  With advances in science and technology, we can change mechanical properties of metals.  One of the most common ways this is done is through case hardening, or surface hardening.

Surface hardening is a heat treating service for reinforcing a metal surface. There are many different types of surface hardening processes but typically, you take a base metal with a low carbon content and then combine it with a thin layer of another metal alloy that has a higher carbon content and is also more durable. Once reinforced, the finished product is a combo of metals that are much stronger; which allows the object to be used for much longer than originally intended.

The concept of metal surface hardening has been around for centuries and originally was used for things like strengthening cooking utensils and horseshoes. Now, it has many different manufacturing uses including the creation of:

• Carbon steel forgings and pinions
• Machine Parts

How Does Surface Hardening Work?

It’s important to note that surface hardening can be done with both alloy and carbon steels; although, in most cases, mild steels are ultimately used.  To create case hardened steel, you’ll usually need to diffuse nitrogen, carbon and boron into the outermost layer of steel through extreme heat.  From there, the surface needs to be heat treated to the level of hardness that is needed.

Advantages

On top of surface hardening producing a metal that is much harder than the original, the use of an initial low carbon metal also has the advantage of making this material more malleable. This allows manufacturers to create their desired shapes.

Another advantage of this process is not only just the overall strength of the product, but that it helps the iron to avoid becoming weak. Because the inner core is left untouched, the product still possesses flexible properties.

Applications

Surface hardening is a process that is usually done after the component has been created and is in its final state.  Components that are candidates for this process are any that are subject to a lot of pressure or heavy impact.  Some examples of products that are case-hardened include:

• Chains and shackles that need to be able to resist being cut
• Fasteners and many kinds of screws
• Engine camshafts and rifle bolts
• Firing Pins
• Fireplace items and equipment
• Frying utensils and cast iron pans
• Metal panels and metal doors
• Girders
• And many more

Find the Services You Need

Metal surface hardening can be a fantastic way to reinforce parts that subject to impact and pressure.  If you are in need of professional heat treating services, contact the experts at SST.  We service numerous industries including (but not limited to) automotive, rail and aerospace. You can trust us with creating high-quality parts for your business. Contact us today!

If you have ever been to a real blacksmith’s forge or watched one of the popular metal-working reality TV shows, you likely have seen the professionals using quenching heat treatments such as oil quenching. It differs from other common steel heat treatment processes such as case hardening, tempering steel and precipitation hardening and it can be quite dramatic, with steam rising from the cauldron of whatever medium the metalsmith prefers for just the right effect. But for those not used to working with red-hot pieces of metal, the whole process can be a little mysterious. Let’s take a closer look at the concepts behind quenching metal and why one might choose one medium over another.

What Is Quenching?

Quenching is a technique used by metalworkers or metal heat treatment companies after they have treated steel at very high heat. They may have been annealing it, stress relieving it or normalizing it. If the pro doesn’t bring the metal back to room temperature quickly, the microstructure of the metal might change, which will compromise its strength. Annealing also involves a gradual cooling of the metal, but steel quenching is much faster, which could be beneficial, depending on the circumstances.

How Do Metalworkers Do It?

The basic method for quenching steel or metal is to plunge the metal into some sort of liquid or, in other cases, forced air. There often will be a large burst of steam as the red-hot metal hits the surface of the room-temperature liquid. In fact, the steam plays a role in whether the smith has to stir the metal around in the liquid to prevent pockets of moist air.

What Are the Options for Media?

There are a lot of different types of quenching liquids, and each has its particular uses. Water is an effective and simple option, but it also has some significant drawbacks. It cools metal very quickly and helps it reach its maximum level of hardness. However, it can also lead to cracking or distortion of the steel, compromising its utility and potentially rendering it useless.

Many metalworkers chose alternate media such as oils, polymers or salt water. In some cases, air convection is used. Each of the options comes with a specific quenching speed or rate. The slower the metal cools, the higher the chance of changes to the microstructure. Water’s quench rate, for example, is much faster than that of mineral or cottonseed oil.

Why do Metalsmiths Do It?

Metal goes through a complicated set of states as it has been heated and begins to cool. At various parts of the process it can be brittle and need tempering in oil, lead baths or salts. In order to control the finish product’s brittleness, ability to withstand tensile stress and overall strength, the metalworker must carefully control which states the metal reaches and how quickly. A misstep in any part of the process could lead to unsuitable steel.

Of course, the use of the metal is of particular importance. The blade of a weapon requires an entirely different approach than metal that will be used as bolts on a shipping container, for example. The quenching procedure allows for variations in control that yields the right metal product that the metalsmith is looking for.

Steel heat treatment is an essential process in numerous industries. It is the act of altering the chemical or physical properties of a substance, which most of the time is metal. Through the heating process, a piece of metal becomes malleable, allowing a professional to alter its physical appearance into the desired shape. To meet a wide range of demands, there are several different heat treatment process available. Some of which include: case hardening, oil quenching, tempering steel, and annealing steel. Each one has its own unique benefits and times when it is best used.

Vacuum Carburizing

Vacuum carburizing is very similar to plasma carburizing except this takes place in a vacuum furnace system. The gas used in this process is propane, and the furnace is set to a temperature usually in the range between 900° and 1,050° Celsius. The metal undergoes a diffusion state, which allows the metal to obtain a more desired carbon profile. A benefit of using this process is that the metal is altered in a protective environment. Therefore, it is not exposed to toxic off-gases or other forms of oxidation.

Gas Nitriding

Gas nitriding is most commonly used when a piece of metal needs to undergo a thermochemical alteration to make it more resistant to degradation. This makes the surface harder and extends the piece’s lifespan. This process is typically used on pieces of metal that are expected to receive a lot of wear and tear. It is useful for metal parts used in the loading and unloading of materials.

Oil Quenching

In the past, whenever a metal component underwent extremely hot temperatures, it would be treated with water afterward to serve as a quenching medium. While it is still used and effective, there is another method for accomplishing this using oil. This is referred to as oil quenching. Due to the fact oil is unable to boil as rapidly as standard H2O, the metal is able to retain the heat for longer. This process involves putting the component in a furnace set to a temperature in excess of 2,000°. After it has reached the desired temperature, it is placed in a tank filled with oil. With this method, there is a significant drop in the likelihood of unevenness, distortion and cracking.

Stress Relieving

When a piece of metal is cut or physically altered in some way, the internal body undergoes extreme stress. As a result, the piece is much more susceptible to breaking and other types of damage. However, this risk can be substantially reduced by having the piece undergo stress relieving. For effective stress relieving, the piece must be held at the same temperature for a specific amount of time.

The general rule of thumb to follow with this process is that the item should be exposed to an environment that is anywhere between 590° and 680° Celsius. Next, a professional needs to determine how large the piece is. The metal needs to remain at a consistent temperature for one hour per each inch of the metal’s thickness. At the end of the process, the item achieves greater dimensional stability.

Vacuum Brazing

When most people think about two pieces of metal being joined together, they assume it is done via welding. While that is certainly a possibility, there is a more intricate process for more complicated treatments, and it is called vacuum brazing.

With this process, two pieces are joined together using a filler piece. For best results, the temperature of the brazing device itself needs to be lower than the melting point of each of the two pieces of metal. To complete this process, the component needs to be placed in a vacuum furnace to create an environment where contamination is significantly reduced.

Carbonitriding

Carbonitriding is another process of making pieces of metal more resilient against normal wear and tear. However, this treatment is most often used on low-quality pieces of metal to give them the same durability as a higher grade of steel.

It has many similarities to carburizing, but in general, it is far less likely to undergo softening during the process. This process is particularly useful on gear teeth, dies, tools, fasteners, and bearings.

Bright Hardening

Bright hardening is most often used in instances where the person wants the metal to retain a bright finish at the end of the project. This is considered an annealing process in heat treatment where the metal is both cooled and heated in a static environment. Through this, oxidation becomes inhibited. Screw machine parts, springs, stamping and investment castings often need to go through this treatment.

Picking between the different heat treatment process can be a hassle. The best treatment for a part ultimately comes down to what exactly it is and what it is intended to be used for. Each different heat treatment process has its place.

Make sure to use the right one whenever you require heat treatment so that you receive the most benefits out of your parts. Specialty Steel Treating can assist you with choosing between each different heat treatment process and purchasing the right steel heat treatment. Contact us for a quote.

The steel heat treatment industry has become a huge market all around the world. Globally, industries are making major advancements in the operations involving the heating and cooling process of metal. This is due to the wide number of benefits heat treatment and other process such as case hardening, tempering steel, precipitation hardening or vacuum heat treatment offers steel when it comes to certain desirable mechanical and physical characteristics.

According to IHEA, heat treatment consumes 17 percent of U.S. Industrial Energy usage and consists of 2 to 15 percent of the total production cost. Globally, the sheer volume of the heat treatment industry is in the range of $65 to $75 billion—with the sale of heat treatment equipment alone being between $4.375 and $5.5 billion.

Looking at just the numbers, it’s safe to say that the heat treatment industry has a huge impact on the economy all over the world. Many countries have considered the heat treatment process to be a strategic part of their developing economies and living standards. Countries like Poland and China even have significant subsidies and grants provided to manufacturers that develop technologies or modernize their facilities for such processes.

North America alone is a $22 billion industry—with the European Union coming in second ($18 billion) and China ($11 billion) coming in third. Looking at these statistics, it’s clear that the U.S. is a dominant player in the heat treatment market. Largely due to the high volume of automotive parts and processes that are built and handled within the country. On average, 70 percent of a vehicle’s weight is metal. This high percentage of metal has a profound influence over the demand for heat treatment within the industry.

It seems like other countries are starting to catch on too. According to TheMonty.com, “Fast growing Asian/African markets create opportunities for heat treatment services and equipment, particularly in India, Thailand and Indonesia and, in time, Vietnam and the Philippines. This manufacturing shift depends on population size, education (income) and the steel availability in the country or region. We can predict with some degree of accuracy that within the next 10 to 20 years, the highest growth will be in Africa. Egypt, Nigeria, Ethiopia and Ghana will have the fastest growth potential in the heat treatment industry.”

Globally, a number of different industries besides the automotive sector use heat treatment in their everyday processes as well—industries like heavy construction machinery, aerospace, mining, metalworking, and the tool and die sectors to name a few.

The heat treatment market only seems to be getting bigger and better as the years go on. One of the greatest statistics regarding the heat treatment industry is that a majority of industry operators are smaller businesses that serve local and regional markets. According to U.S. Census data, 96.4 percent of heat treatment companies employ less than 100 workers, and 68.3 percent employ fewer than 20.

Meaning that the industry is made up of thousands of companies that all specialize in a particular segment of the industry—showing just how diverse and how much depth there is to what we do. Trends in the heat treatment sectors are also on the rise. Digitalization and a globalized standard of heat treatment have both played a big part in the industry’s growth. Automation and manufacturing technologies and processes are constantly becoming more digitalized and streamlined, making our sector even more efficient and lowering the cost of overall production.

Looking at these industry market statistics, analyses and trends makes one thing abundantly clear. The heat treatment industry is a huge player in our global economy, and it’s definitely one that’s here to stay.

Steel parts often require some form of heat treatment to achieve an increase in hardness and obtain maximum strength and durability. Through the many different processes of heat treatment, the properties of steel are changed via physical and mechanical channels. Among many other benefits of heat treatment, it can also aid in the manufacturing process.  There are a variety of steel heat treatment processes including: case hardening, tempering steel, oil quenching, carburizing, vacuum heat treatments and more.

When we talk about the change of mechanical properties, we’re referring to the shear strength, toughness and tensile strength of the steel. Allowing for this mechanical change in properties enables your product to be more efficient in its daily duties and more resistant to wear and tear during even its toughest jobs.

There are a number of different heat treatment options to choose from—and they all are dependent on the properties required for the steel’s end function. It’s essential to work with an established company that recognizes these differences to ensure that your product meets the specified requirements you have in mind for it.

Like we mentioned, the right heat treatment will alter both physical and mechanical properties of your material, and it aids in other important manufacturing steps as well. The result of a properly applied heat treat processes can relieve stresses, making the steel easier to machine or weld. Steel materials benefit greatly from the benefits of heat treatments in regards to manufacturing, particularly in processes such as hot forming or after welding, where stresses may have been built up over time.

Heat Treatment Does a Lot for Steel

Heat treatment doesn’t just make steel harder. It can actually make it softer too! The softening of steel allows for metal working operations such as deep drawing, cold forging and machining. Thus, steel also increases its strength, making the material ductile or more flexible, while also introducing wear-resistance characteristics, making the material tougher.

Case hardening is an example of this—a simple process of hardening the surface of metal while allowing the metal deeper underneath to remain soft, thus forming a thin layer of hard metal on the outside. Case hardening provides you with a part that will not fracture (because of the soft core that can absorb stresses without cracking) but also provides adequate wear-resistance on the surface of the part.

Gears, shafts, bearings and other crucial components benefit greatly from case hardening processes such as this when we talk about not only their wear-resistance, but their overall lifetime as well. Meaning that through these operations, fatigue-resistance is also increased which leaves steel components working more efficiently for a longer period of time.

Extremely hard steels are often used in applications as cutting tools where highly defined edges must be maintained—heat treatment of these steels is a critical operation to obtain the performance and job required of them. Hard surfaces with ductile base material may be developed by heat treatment as well. The possible applications and uses for heat treated steel seem to be endless.

If an increase in material strength and wear-resistance is required, then a heat treatment of some form must be given. This is the best way to achieve maximum usage and performance out of your material. Heat treating is a significant part of the steel industry and forms as a basic function of the industrial infrastructure.

Benefits of Heat Treatment in a Nutshell

We went through so many! Let’s break down all the benefits of heat treatment towards your steel parts and components.

• More durable product.
• Steel becomes tougher, stronger.
• Easier to weld.
• Becomes more flexible.
• Increases its wear-resistance.
• Increase in overall lifetime of the part.

Our heat treatment capabilities will leave a lasting effect on your precious material. There are a ton of benefits of heat treatment for your production line. Find out how Specialty Steel Treating, Inc. can get your steel to reach its maximum potential. We will analyze your manufacturing processes and choose one of our industry-leading services, one that best suits your specific needs. We understand how important your product is to your bottom-line, and we have the tools and techniques to provide you with nothing but the best results.