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Does Heating Metal Make it Weaker?

Monday, April 8th, 2019
Heated metal getting weaker

Achieving the perfect metal properties often requires heat. There are many different ways that heat can alter the properties of metal. However, does heating metal make it weaker? Here are some common ways that heat treating metals changes the basic properties and strength of metal.

Metal Transformations

Metals can be changed to acquire or improve certain traits that are important for different roles in different industries. If need structural elements for architecture, you’ll search for a material with very different qualities than electrical wiring. Here are three basic ways that metal is transformed with heat treatment:

  • Structure: By displacing atoms, heat can form new metallic structure. Also known as allotropic phase transformation, this is an essential transformation that is used with iron and steel heat treatment.
  • Magnetism: Perhaps the most common way that heat makes metal permanently weaker is with a magnetic charge. Heating nickel, iron and cobalt to temperatures ranging from 626 to 2,012 degrees Fahrenheit can cause these metals to completely lose their magnetism. Magnetism can be useful in some instances, but in others it can be unnecessary or inconvenient.
  • Thermal Expansion: This transformation is not only used when crafting metal products but also can be a liability. Metal expands in volume, length and surface area as it heats up. This can continue to occur even as the metal is shaped and put to use, so everything from sewer pipes to bridge cables needs to account for thermal expansion.

These are the basic ways that heat can alter the characteristics of metal. However, when heated and cooled in specific ways at specific temperatures, heat can alter metal in far more unique and specialized ways. Learn how heat treatment can specifically alter metal to fit a variety of different needs such as malleability, hardness, softness, magnetism and more.

Heat to Alter Metal

The short answer to the question regarding making metal weak is yes, however, only for some metals. The process of annealing can soften a variety of metals. Brass, steel, iron copper and silver can all be made weaker by heating the metal to a set temperature and cooling it slowly. It’s not only used to create softer metal products but also more electrically conductive ones.

However, it would be incorrect to state that heat always makes metal weaker. Hardening is another process used by heat treating companies to actually create more durable metal components. This is used for steel and similar alloys and creates hard, yet brittle metal.

Another popular process where heat is used to alter metal is tempering. Tempering increased the ductility of hardened steel. It is used to keep the benefits of hard steel, with less of the brittle qualities.

Finally, normalizing alloys is another common way to treat metal using heat. It starts with heated metal that is air cooled. This simple act, if heated to an exact temperature range, can create a more pure, hard metal. It’s often used to create steel that is stronger than annealing the metal, but also creates a less ductile product.

So, heat can indeed make metal weaker. However, there are many processes where metal is strengthened by heat. The alloy, temperature range and cooling methods all need to be considered before determined whether metal will increase or decrease its hardness through heat treatment.

Discover the Best Heat Treatment Service Whether you’re searching for weaker, more malleable metal through heat treatment or stronger, more durable products, SST offers one of the most professional and exacting steel heat treatment services in the country. Discover why we’re the only approved company for heat treatment of specific flight safety configurations. If you have any more questions about heat treatment and metal processing, or if you need any services from one of the best heat treating companies in Michigan, contact us today.

What Is Case Hardening?

Monday, March 4th, 2019

Metal must be pliable to be suited to a variety of applications. However, a metal must also be durable, especially when it comes to surface strength. These two characteristics are integral to ensure optimum function and reduce the effect of excessive wear and tear. That’s where case hardening, which is also referred to as surface hardening, comes in. This process enhances surface strength while allowing the core to remain flexible. Specialty Steel Treating offers this and many other essential heat-treating services to clients. Thanks to their extensive knowledge in surface hardening, they’re able to offer the following information so you can make the best decision regarding your metal-treatment needs.

How Does This Process Work?

what is case hardening of steelCase, or surface, hardening increases the surface strength of metal without impacting the inner core of the part. This is accomplished by adding another layer of metal to the surface, which helps decomposition due to repetitive stress. Case hardening steel grades depend on the temperature used during the treatment process. For example, an initial carbon temperature ranging between 1650 to 1700 °F produces an SAE steel grade of 1016. The method and solutions used to cool metals can also have an impact on SAE grading.

Are There Different Types of Surface Hardening?

When increasing the surface strength of steel, you have a few different options at your disposal:

    • Carburizing: This method entails placing metal in a high-temperature environment along with a carbon-based substance, which infuses the surface with carbon. Atmosphere carburizing entails placing metal into a furnace and introducing gases like methane or carbon monoxide. Vacuum carburizing also involves the injection of gases, but in this case the metal is in a vacuum-sealed container.
    • Induction Hardening:  Induction hardening is another type of carburizing. Metal is heated via electromagnetic induction before being rapidly cooled. Cooling agents include water and polymer solution sprays, which are dispersed directly onto the metal. Induction hardening is best for metals containing a carbon content of at least 0.4% or higher.  
    • Nitriding: Surface strength can also be enhanced using nitrogen. In this case, metal is heated using gaseous ammonia at a temperature ranging between 950 and 1,050 °F. How long the metal is treated correlates to how deep nitrogen is diffused into the surface.
  • Mechanical Hardening: Some hardening methods don’t require extreme temperatures to increase surface strength. Some types of mechanical hardening utilize cold-working, which involves hammering or rolling metal at room temperature. Metal can also be shot with iron pellets or blasted with air.

What Are the Benefits?

When a metal has a strong outer exterior and a soft inner core it becomes far more durable. These properties make it resistant to wear and tear as well as shock, which will be absorbed by the pliable core. When metal is more resilient it also has a longer lifespan, which prevents the need for frequent parts replacements. Flexible metal is also much easier to weld. As a result, a piece can be molded into a variety of shapes depending on the application in question,

What Are the Applications of Case Hardening?

Case hardening guns is a common practice. Continuous firing of a weapon creates heat, which in turn deforms the gun barrel. When barrels are heat-treated, a gun becomes far more stable. Not only is accuracy improved, but routine maintenance like cleaning is also much easier to perform. Heat-treatment also has applications in the automotive industry. Car parts are often case hardened to withstand repeated stress associated with running a vehicle. This includes universal joints, shafts on water pumps, and pinion gears. Other applications include parts used in the aerospace industry, heavy equipment pieces, railway components, and tooling equipment.

What Are the Next Steps?

Specialty Steel Treating has earned a reputation for quality among its numerous clients occupying many different industries. They can help you select the best hardening process for your needs by using more than six decades of experience. If you’d like more detailed information, feel free to request a quote using their convenient online contact form. You can also learn more about their services by visiting their website.

Air Quenching: What is it and How is it Useful

Tuesday, February 19th, 2019

While many metal fabricators will be familiar with heat treatment, not everyone is as familiar with the term air quenching. As Specialty Steel Treating, Inc. is an established and respected heat treating company, we understand the importance of air quenching steel for tools to aid in the manipulation of a variety of properties, like ductility, strength, elasticity and hardness, but what exactly is air quenching and how does it relate to the heat treatment process?

Quenching Definition

air quenching steelQuenching is described as the process of rapidly cooling metal during the heating process. This process is critical to returning metal back below its critical temperature. While quenching is a blanket term to refer to the cooling process, there are two methods typically used to attain this result: Fluid quenching and air quenching.

Fluid quenching utilizes chemicals or other liquids to cool the piece. The substances most often used are water, oil or brine. Essentially, a heated metal piece is either submerged in a cooling bath, or the liquid is forced over the part to cool it down.

Air quenching is similar to fluid quenching in that a cooler source is used to bring down the temperature of a workpiece. Air quenching utilizes either air of inert gases that are then forced over the piece to cool it down.

Importance in the Hardening Process

Using an air quenching cooler boiler aids in the hardening process of metals. To harden metals, they must first be heated and then cooled at varying rates, depending on the specific alloy being hardened. As the material cools, it may become brittle which then requires tempering of the substance.

Prior to hardening, many substances that are commonly accepted as durable and strong, like cast steel and iron, are actually soft due to their uniform and layered grain structure, which consist of a mixture of ferrite and cementite called pearlite. By heating these substances and this mixture past a certain temperature and then rapidly cooling it through the quenching process, the pearlite substance is then transformed into a substance known as martensite, which is highly durable and resistant to distortion.

Uses of Air Quenching Steel and Other Material

While quenching may seem limited in its applications, the process is necessary for a variety of manufacturing and industrial applications; for instance, air quenching aluminum or other alloys for specific applications and designs. The method of quenching allows for the hardening of materials at different rates, but this variability leads to the production of useful metals and elements and tools, like cutting blades and other industrial components. The ability to create strong and durable alloys that have a distinct resistance to distortion and flex allows for solid metals and further structural fabrication.

While the exact definition of air quenching may be lost on many consumers and even some industry professionals, the process is invaluable to the metal fabrication and construction industries. There are a variety of uses for quenching and not every application will require the same level of hardening, but the quenching process allows for reliable metalworks that are both durable and long lasting.

If you are unsure of the benefits of quenching or are interested in using air quenching as opposed to fluid quenching, then contact Specialty Steel Treating, Inc. today. A representative will be happy to walk you through all of your heat treating options, ensuring that you are well aware of the best practices for your specific application. Don’t depend on information from outside sources, talk to a knowledgeable professional, someone who understands the merits of the overall treatment process, and can provide you with the answers to all your heat treatment questions and concerns.

Case-Hardened Steel

Thursday, January 3rd, 2019

Case-hardened steel means creating a thin layer of a harder alloy on a metal surface by infusing elements onto it. The harder alloy on the outer surface is called the case, while the inner structure is called the core. Speciality Steel Treating offers several different methods of case hardening your steel.

Properties of Case-Hardened Steel

case-hardened steel

Case hardened steel properties include a core that is tough surrounded by a case that is hard. This gives the case hardened metal components extra durability as the core, or case depth, retains the ability to absorb shock while the hard outer case provides extra strength. Steel that is case hardened is equipped to resist the following:

  • Abrasion
  • Corrosion
  • Wear

By contrast, a component that is not case hardened may develop cracks below the surface that cause pitting and flaking when they finally reach it.

Difference Between Case Hardening and Surface Hardening

Surface hardening involves keeping the core below its austenitizing temperature while heating the surface and then immediately quenching it (i.e., plunging it into a cold liquid) after that temperature is reached. This causes the core of the metal to remain soft while the surface hardens.

How To Case Harden Steel

Because case hardening involves adding an element to the metal, the different case hardening processes are named according to the element added. These elements include the following:

  • Ammonia or other nitrogen-rich gas (nitriding)
  • Nitrogen and carbon (cyaniding)
  • Carbon (carburizing)

Case hardening steel involves infusing elements onto the heated metal surface and then quenching. The heating can be done by flame, in a vacuum chamber, or by electromagnetic induction.

The case hardening method used depends in part on the carbon content of the metal. Induction hardening is usually performed on steel that already has a significant carbon content because the process does not add any carbon to it.

Learn More About Case Hardening Steel

Large or small, simple or complex, case hardening has benefits for many steel components or tools. For more details, or to request an estimate, call Specialty Steel Treating at 586-293-5355.

Heat-Treated Metals Make Everyday Life Possible

Monday, November 26th, 2018

It is easy to take things for granted. You wouldn’t think twice about sharpening your favorite chef’s knife because it is dull. Did you ever wonder what would happen if the bearings, gears and axles in your car were made the same way? If they were, your car would wear out in a few weeks. The biggest difference between the steel in knives and that in moving engine parts is in the way they are heat treated. Nobody is better at heat treating metals than Specialty Steel Treating, Inc. of Michigan and Connecticut.

Heat Treat Metals to Survive Hostile Environments

heat treating metal

Imagine the harsh operating conditions of moving parts in cars, trucks, locomotives, heavy equipment and aircraft. There is heat, pressure, friction, exposure to corrosive materials and repetitive motion over many millions of cycles. With the assistance of lubrication, heat treating metal hardening is what makes the long working life of these moving parts possible.

Heat Treat Metals for Utility and Safety

Your favorite chef’s knife is a perfect example of how heat treating improves utility and safety. First, your knife needs to be flexible and yet hard enough to hold an edge. One thing it must not do is break. A knife that breaks under any circumstances is a danger to the user and anyone close by.

Heat Treat Metals To Make Them Last Longer

Custom tools and dies represent a significant investment to manufacturers. If they are too brittle, they can break. If they are too soft, they can wear or deform and make parts that no longer meet specifications. However, if they are processed in a metal heat treating furnace by skilled technicians, their resilience and useful life can be greatly improved.

Heat Treating Is Something Worth Considering

If you manufacture metal parts and wonder if they would benefit from heat treating, contact the experts at Specialty Steel Treating, Inc. by phone at (248) 478-5900. Tell them what you manufacture, and they will help you make it better.

Gas Nitriding Is a Great Way to Case-Harden Metallic Items

Monday, November 26th, 2018

Simply put, gas nitriding is the process of infusing nitrogen atoms into the surface of items made of steel, aluminum and other metals. This is accomplished by heating the metal to 520°C/970°F and introducing nitrogen-rich ammonia. The exterior of the item is hardened, leaving the metallic properties of the interior unchanged. It is heavily utilized on automotive components like crankshafts and gears. It is also used to harden dies and machine tools. Liquid nitriding is one of the many hardening services offered by Specialty Heat Treating, Inc.

Liquid Nitriding Offers a Different Approach to Case-Hardening

nitriding temperature

In this process, the item is heated to the desired temperature (550°C/1,020°F to 570°C/1,060°F) and then immersed in liquid cyanide salt. The process infuses nitrogen more deeply into the item; however, it also infuses additional carbon. As with all hardening processes, the metallic properties of the interior are unchanged.

How to Choose Between the Two Nitriding Methods

It’s time for the main event – liquid nitriding vs gas nitriding. Both processes case-harden items but consider the following differences before choosing a method.

  • The gas nitriding temperature is 520°C, lower than the 550°C to 570°C temperature required for liquid nitriding.
  • The material that contributes nitrogen to the gas method is the toxic chemical ammonia. However, it is not nearly as dangerous as the highly toxic cyanide salts used in the liquid method.
  • The nitrogen infuses to a deeper level with liquid nitriding than it does with gas nitriding. Potentially, this could be undesirable if the item being hardened has some areas where the metal is very thin.
  • Liquid nitriding infuses additional carbon in the item being processed. Whether this is good, bad or irrelevant depends on the circumstances.

Help Is Just a Phone Call Away

Despite the differences, the results are virtually identical for most applications. When it comes to nitriding, you can depend on the experts at Specialty Heat Treating, Inc. to do it right. Contact us at (248) 478-5900 to discuss your requirements.

Five Things You Probably Didn’t Know About Heat Treatment

Friday, May 18th, 2018

Did you ever wonder how the skinny rail tracks do not get crushed under the weight, speed and impact of a train? It is because they are strengthened with heat treatment to withstand extreme pressure and wear. Heat treatment is an ancient method used by blacksmiths to mold metal. At SST, we have offered precision-controlled metal heat treating services for over 60 years. We provide a variety of processes in a myriad of industries for parts small and large that travel through earth, water and space.

annealing heat treatment

How Do Our Metal Heat Treating Services Work?

Heat treating employs the extremes of hot and cool temperatures to alter the physical constitution of a metal and produce desirable levels of hardening or softening. The granular structure of the material is manipulated to shift its mechanical properties for achieving specific levels of toughness, malleability, ductility, strength and resistance to corrosion. Learn more about our methods through the following heat treatments:

  1. Case hardening strengthens the surface of steel while maintaining a softer core. In this process, carbon is diffused into the material through various means, such as gas carburize, gas nitride, vacuum carburize and carbonitride. By utilizing an interplay of gases, air and vacuum, the surface of the metal is hardened and made corrosion resistant. The vacuum treatment protects the surface of metal by application of a pressure vacuum to austenitize metal after high heat. This cost-effective process allows for lower gas consumption and short carburizing and processing cycles.
  2. Quenching heat treatment enhances the mechanical properties and durability of a metal. The steel is heated above its upper critical temperature limits and then quickly cooled with the help of elements like oil, water, gas or molten salt, which cool at different speeds and produce varying levels of hardness. The method of quenching heat treatment is chosen based on the type of steel, which then is aged, stress relieved or tempered for stability and internal stress reduction.
  3. Tempering reduces the brittleness of steel, making it more suitable for applications. The steel is heated below the transformation temperature threshold for a certain amount of time, depending on the alloy and desired performance, and then cooled. Tempering enhances ductility and reduces hardness.
  4. Cryogenic hardening treats the metal to extremely cool temperatures – around -300°F – using liquid nitrogen to fully eliminate austenite and reduce thermal stress. It also makes the material corrosion resistant.
  5. Annealing heat treatment is used to make metals more pliable by heating them to a specific temperature followed by slow cooling, altering their microstructure. This improves their electrical conductivity and makes them more malleable for cold working.

Why Should You Contact Us?

We offer metal heat treating services in various industries: automotive, aerospace, heavy equipment, firearms, industrial, rail, and tool and die. We are the only approved commercial company in the country for certain configurations for prime aerospace, and we bring this standard to all clients.

With our experience and breadth of services, we are well positioned to handle your heat treatment needs. Find out more and end your search for metal heat treating services. Your satisfaction is guaranteed.

Why is Surface Hardening Done?

Wednesday, April 18th, 2018

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

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!

Why Manufacturers Heat Treat Firearms

Monday, February 26th, 2018

No matter if you use your guns for target shooting, hunting or home defense, you expect them to work whenever you pull the trigger. With so many precision parts in a typical rifle or handgun, it only takes one misaligned component to completely disrupt the firing process. One of the ways manufacturers cut down on these problems is by using firearms heat treating services on the various metal components of each weapon. Here’s an overview of why manufacturers heat treat firearms and why this is such an important step in the manufacturing process.

firearms heat treating

How Heat Treatments Work

You might think of steel as a relatively hard metal, but it takes a lot of work for it to reach its maximum firmness. Once ore is extracted from rock and smelted to the right consistency, it starts out with a relatively brittle profile. When a blacksmith finishes making a sword, knife or other piece, he or she submerges it in a quenching liquid that further solidifies the hot alloy. Depending on the type of metal, this bath could either be water or oil that reaches temperatures of up to 1,700 degrees. The same thing can be done with a gun barrel, as manufacturers want these components to achieve peak firmness.

Manufacturers and Firearms Heat Treating

Pressure is one of the most important aspects of any firearm, as it takes a concentrated force to give the bullet maximum velocity. Every time you chamber a round and fire it, the back end of the barrel pressurizes due to the ignition of the gunpowder, and a flame reaching temperatures up to 5,000 degrees shoots up the barrel’s length. With so much force pushing outward on the metal, it’s only a matter of time before it starts to warp, buckle or crack. A typical firearm manufacturer will work with a heat treatment company to increase the number of rounds a rifle can shoot before significant maintenance is necessary.

Symptoms of Barrel Damage

When a part of your body starts to wear out, you start to notice symptoms, and the same is true of a precision firearm. If you aren’t getting typical results out at the range, you might be experiencing a problem. Here are some signs that it might be time for a repair or replacement:

• Decreased accuracy
• Misfires
• Shorter range
• Slower velocity

While even the toughest barrels will eventually break down due to repeated firing, components serviced by metal firearms heat treating companies should last a great deal longer. You’ll also be able to turn around much quicker for your next shooting session without worrying about damage due to overuse.

Ensuring Maximum Strength

Now you know the reasons why gun manufacturers use heat treating services, you hopefully have a better understanding of the work that goes into the construction of a precision firearm. If you’re an amateur gun maker, it’s important you leave this step to a professional to avoid a mistake during treatment can leave you with metal that’s too brittle, which could create a dangerous situation. When it’s time to heat treat your firearm, give us a call so you can rest assured that you’ll fire straight and true with every shot.

Things You Should Know: Quenching Metal – Explained

Monday, January 15th, 2018

Quenching Metal – Explained

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 the quenching heat treatment. 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.

quenching metal

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.