What is Heat Treatment?
New Years are often those times when the “new you” mindset is strongest throughout the world. Gym memberships spike, diets, start, personal/themed blogs start, and to be completely transparent, company blogs start to. It really is the perfect month for beginning. Hence, welcome to Can-Eng Furnaces International’s entrance and inaugural blog post. Through the year we will use this venue to offer up basic education on the industry, recaps of events, whitepapers, and insights by our experts on what they see happening, now and in-the-future, for the heat-treating industry.
Today, we begin with the most basic aspect of heat treating – ‘What is Heat Treatment’? A simple, honest question (for most outside the industry or relevant education spheres) that presents us with one of the most interesting aspects of the heat treatment industry. Beyond its immediate sphere of impact, it is one most of the general populace don’t know exists. Making this more remarkable is the fact that heat treatment affects nearly all aspects of modern life: construction, automotive, aerospace, oil & gas, and military are just some industries that rely on heat treatment as part of their product pipeline. Everyday items, such as: steel plates, pipes, engine blocks, pistons, springs, to simple fasteners are all products that receive heat treatment. So, let’s explain the unknown, hidden industry.
Heat Treatment Background Info
Simply stated, heat treatment is the process of using heat at various, staged levels to change the physical properties (microstructure) of a material; most often metals (i.e. steel or aluminum). Heating is carried out in large-scale, industrial “furnaces” (extremely different from a house-hold furnace, capable of reaching temperatures beyond 2000oF).
Heat treatment, typically, proceeds as follows:
- Item ‘A’ enters the heat treatment cell and is loaded into the first furnace
- Item ‘A’ is brought to a predefined temperature and held (soaked) at that temperature for a specified time (soak time)
- Item ‘A’ exits the furnace and is cooled (quenched), often rapidly, to another distinct temperature.
- Following quenching, Item ‘A’ is loaded into a second furnace where it receives a second round of heating and soaking, to “fine-tune” the physical properties of Item ‘A’
This four-step process is the most basic heat-treatment process. There exist a multitude of supplementary processes to compliment the heat treatment, to achieve the desired final properties. Do you need a high-hardness, abrasion-resistant? Heat treat it. Need something with high strength with enough ductility to not shatter? Heat treat it. The options are nearly endless, and here, is where the simplicity of heat treatment and manufacturing heat treating equipment fades.
While initially straightforward in practice, heat treating quickly fractures into multiple, isolated & interconnected variables (soak temperature, soak time, temperature uniformity, ramp-time, quench rates) that transform the process into a detailed, intricate science. However, before we go any further, there is some key, industry-wide jargon that must be defined to allow for a basic understanding of the industry.
The appearance of a material when viewed at nm-cm length. More appropriately, it is the arrangement of phases and defects within a material. Microstructures affect all aspects of a material’s physical properties. Heat treating aims to develop specific microstructures within a material.
A mixture of two or more chemical elements, at least one of which being metal, with metallic properties
A solid mixture of iron and carbon (can be other elements). Formed when a material is above its critical (transformation) temperature.
Also known as transformation temperature it is the temperature range under which ferrite changes to austenite.
A magnetic form of iron, with a body-centred crystal structure
Process of shaping metals by hammering or pressing. Heat treating allows for a metal’s shape to be changed, more than if it were cold, without adding unnecessary strain in the metal
Rapid cooling of metal alloys. Several types of quenching exist and will be covered throughout the course of the blog
Heating a metal component for a defined length of time at a pre-defined temperature to achieve a uniform temperature throughout the component.
Fortunately, for heat treaters and manufacturers of heat treating equipment, material science is a heavily-researched field of study. Rules-of-thumb no longer dictate what needs to be done, whitepapers and data clearly define the exacting environments under which heat treatment must occur. This responsibility falls on the manufacturer of the industrial furnace systems, massive systems must perform on the smallest details. This is where the intricacy and science of the industry come to the forefront, and what we hope to demonstrate through this year. The marvel of these detailed, highly engineered industry, that supports so much of our daily life without most noticing.
As we mentioned above, the intricacy of heat treating begins with the type of material in need of heat treatment – steel has different processes than aluminum, for example. These differences will serve as the basis for our first series of posts for us as we dive deeper into the heat treatment industry. We welcome you on the journey through 2018 with us here at Can-Eng Furnaces. For our next post, we will begin to focus on the specifics of heat treating a unique material, starting with the world’s backbone, steel.