Benefits of Heat Treating Metals
The heat treatment of metal involves the heating and cooling of metal. Metal is heated to a specific temperature and then cooling occurs to harden the heated material.
By applying heat treatments to metals, you can modify the metal’s microstructure or chemical composition to alter its corrosion resistance, magnetism, durability, heat conductivity, and electrical conductivity. A part can go through a series of heat treatments to get to a desired performance.
Heat treating improves manufacturability by removing internal stresses from previous metal working processes.
Heat treating can improve wear resistance by hardening the material. Metals including steel, titanium, Inconel and some copper alloys can be hardened either on the surface, case hardening, or all the way through, to make the material stronger, tougher, more durable and more resistant to wear.
Improved strength and toughness are another benefit. Heat treatment can affect the yield strength, tensile strength, and fracture toughness.
Heat treatment processes can improve magnetic properties. Several metals such as 1008 steel or 316 stainless steel can gain magnetism when work-hardened. Annealing can reduce the magnetic permeability which is important if the part will end up in an electronic application.
Why is heat treating important for the manufacturing industry?
Heat treating manufactured parts is an essential part of the metal manufacturing process.
Perhaps the most important aspect is the part performance and can be increased through heat treatment as the process:
- Increases strength, making the metal more ductile
- Introduces wear resistant properties to the metal
- Relieves stresses from work hardening, making the part easier to machine or weld
- Improves brittleness
Part longevity and performance is especially important in aerospace and automotive applications.
The Process for Heat treating Deep Draw Components
Heat treating is a general term for many different thermal processes used on various metals, the processes are used to enhance or modify the properties of the material to meet the requirements of the intended application.
Although there are many types of heat treatment for metals, they follow similar processes. The first step involves the heating of the metal to the required temperature, in some cases up to 2400 degrees. The metal is held at the necessary temperature for a specific amount of time before cooling. While the metal is hot, the physical structure of the metal changes. The soak time is the amount of time used to heat the metal.
The most common methods for heat treating deep draw parts include:
The annealing process involves heating and soaking metal at a critical temperature before cooling it. This helps relieve internal stresses and makes the metal less likely to break or fracture while being formed. There are several annealing techniques such as full annealing, recrystallization annealing, partial annealing, and final annealing.
Normalizing is another annealing process that involves heating the metal up and cooling it at room temperature at a much faster pace than typical annealing.
To harden a part’s exterior without altering its interior, the case hardening process is typically used. Case hardening creates less brittle, more workable parts than other methods that increase hardness throughout the metal. One form of case hardening involves heating metal in a carbon rich environment called carburization, as this increases the metal’s surface strength and carbon content.
Precipitation hardening or aging creates strong yet lightweight metals. If working with a lightweight metal, you can heat it to a high temperature, quench it, and heat it to a lower temperature for an extended amount of time to disperse the precipitates evenly throughout the metal’s grain structure to increase its strength and hardness.
Deep draw forming can cause stress to build up within parts which can weaken them and reduce their overall quality. Stress relieving will remove residual stresses and improve its mechanical properties without altering its structure or hardness. Stress relieving is a heat treatment process in which a metal is subjected to a constant temperature that is below the metal’s critical temperature, followed by controlled cooling.
Quenching and Tempering
This is a two-part process that increases the hardness, ductility, and resilience of metals. During quenching, the metal is heated to a high temperature, changing its crystalline structure allowing it to absorb more carbon. The metal is then rapidly cooled to lock in microstructure changes.
Here at PMP, we carefully select our heat treating vendors based on ISO certification, Nadcap accreditation and other necessary criteria. Our supply chain is local, and this proximity has led to a great deal of flexibility in meeting our customers needs on short notice. It is easy to meet face to face with our suppliers to tackle issues or view processes on site.