Ever wondered how steel is so applicable in so many things? It’s because heat treatment allows metal to alter its physical properties to cater to each desired manufacturing purpose.
Heat treatment was commonly used centuries ago. The discovery of heat treatment processes undoubtedly helped set off a significant period of technological advancement. There are 4 common heat treatment processes that are used to alter the mechanical and chemical properties of the material according to it’s respective purpose. Heat treatment can alter the material properties such as the hardness, strength, toughness, ductility, wear resistance, elasticity, and magnetism.
Heat treatment mainly involve 3 stages, the heating stage, the soaking stage, and the cooling stage.
- The heating stage
During the heating stage, metal is heated to the desired temperature in a span of time. This is because uniform heating is crucial. If the metal is heated unevenly, one section may expand faster than the other resulting in fractured. This apply specifically to larger items as more time is needed for heat to be transferred.
- The soaking stage
The soaking stage of heat treatment is a crucial step in the process of modifying the properties of a metal. Once the metal has been heated to a specific temperature, it is held at that temperature for a certain duration during the soaking stage. This allows the heat to penetrate evenly throughout the metal, ensuring uniformity in the desired microstructural changes promote austenite formation and recrystallization process in the ferritic matrix.
- The cooling stage
The cooling stage, known as quenching, is pivotal in heat treatment, altering a metal’s properties post-heating. Rapidly transferring the heated metal to a quenching medium like water, oil, or polymer solutions induces swift cooling, crucial for desired outcomes. This rapid cooling triggers microstructural changes, such as the formation of martensite in steel, enhancing hardness but potentially rendering the metal brittle. Controlling the cooling rate is vital to prevent issues like cracking or distortion. Ultimately, quenching is indispensable for tailoring mechanical properties like hardness, strength, and wear resistance, vital across diverse industrial sectors, including tool manufacturing, automotive, and machinery production.
The 4 basic heat treatment:
Photo by Kateryna Babaieva
Hardening
From the word itself, we can already guess this heat treatment is used to increase the hardness of the steel. Hardening and quenching are two interconnected processes commonly used in metallurgy to enhance the hardness and strength of metals, particularly steel. Steel is heated to a temperature higher than its transformation point to form austenite, then cool rapidly to form martensite. This rapid cooling is typically achieved by immersing the heated metal in a quenching medium, such as water, oil, or polymer solutions. Hardness and toughness are a trade-off, as only reduce the toughness we could increase the hardness. This makes steel more brittle.
Tempering
Tempering plays a vital role in improving the workability and machinability of steel by relieving internal stresses induced during hardening. This process involves heating the steel to a temperature range of 125-700°C and then allowing it to cool naturally in the air. During tempering, internal stresses are alleviated, and the crystalline structure of the steel is adjusted. Unlike hardening, tempering is conducted at lower temperatures. Tempering is essential for achieving a balance between hardness and toughness in steel, making it suitable for various engineering applications. This includes precision machining, where the material must withstand cutting forces without fracturing.
Our SSA7225 (AISI4140) and SSA6582 (AISI 4340) offerings are meticulously crafted with a quenched and tempered treatment. This specialized treatment enhances their mechanical properties, making them ideal for a wide range of applications in general mechanical engineering. From gears to eccentric shafts and steering components, these materials exhibit superior performance, ensuring reliability and durability in critical components.
Annealing
Annealing serves a crucial purpose in metalworking, particularly for materials like SKD11 and SKD61, which we proudly supply. These materials undergo annealing to boost its ductility and ease its hardness, making it much more manageable for various fabrication processes. During annealing, the steel is heated to precise temperatures and then gradually cooled in a controlled manner. This cooling phase often involves immersing the steel in materials like sand or ashes, which have low heat conductivity, allowing for a slow and uniform cooldown. The result? Annealed steel is typically softer than tempered steel, making it much easier for profiling. Once the final product is formed, it undergoes a hardening heat treatment to transform it into tool steel. This process ensures that the steel possesses the necessary hardness and durability for its intended application.
Normalizing
Normalizing helps to removes internal stress by removing impurities and improved ductility. Even so, normalization steels are still harder compared to annealed steel. Which makes it suitable for steel parts subjected to high impact. Normalizing is only suitable for ferrous metals. The temperature of the normalization is based on the amount content of each respective metal and is approximately 150 to 200 degrees Fahrenheit higher than the range used for annealing.
At Special Steel & Alliance, we understand that every project is unique and requires customized solutions to meet specific requirements. That’s why we’re committed to providing heat treatment services that are tailored precisely to your needs. Whether you’re seeking to enhance the hardness, strength, or other mechanical properties of your steel components, our team of experts is here to collaborate with you every step of the way. From initial consultations to final delivery, we prioritize understanding your objectives and ensuring that our heat treatment processes align perfectly with your specifications. Our comprehensive range of heat treatment options allows us to offer a flexible approach to meet diverse customer demands. Whether it’s annealing, hardening, tempering, or any other specialized treatment, you can trust us to deliver superior results that exceed your expectations.
