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Heat Treating Metals: 4 Solutions

July 2nd, 2021

Heat treating metals is a critical step in the manufacturing process. Whether you’re creating finished products for the end user or preparing materials for a manufacturer, explore these four key solutions and how they can improve the mechanical features of your metal.

Heat Treating Metals

While there are several distinct methods for heat treating metals, they all use the same basic features. Heat treating uses specific temperatures applied at specific amounts of time before being cooled.

All three variables are altered to achieve different results. Consider the results you need, as well as the materials you’re treating, before you choose the best treatment for your process.

4 Heat Treatment Solutions

Alter your metal to prepare for precision machining. These four methods for heat treating metals are capable of delivering the results your process needs:

1. Annealing
2. Normalizing
3. Hardening
4. Tempering

Annealing

Choose steel, aluminum, silver or your desired ferrous metal that requires high levels of ductility. Annealing brings the temperature up slowly, then soaks the material. A slow cooling process occurs to gradually bring the metal down to room temperature.

This process uses a more gradual cooling method than normalizing. The part is cooled in an insulated material or in the furnace itself, rather than being removed and cooled by air.

Enjoy a more formable material for less risk of fracturing during the fabrication process. This is a common process to remove residual stress from metals that have been cut or processed before the heat treatment.

Normalizing

Higher levels of heat and more rapid cooling creates a normalized part. Similar to annealing, normalizing offers a machinable, ductile component that’s still strong enough for many applications in various industries.

To start, the material is heated gradually. The temperature is approximately 150 to 200 degrees Fahrenheit higher than the range used for annealing. This higher temperature is held for long enough to transform the grain structure of the metal.

Smaller austenitic grains that are created during the heat process are transformed to refined ferritic grains after the air cooling process. Air cooling relies on the mass of the material to determine the cooling time. This means that thick and thin parts will have differing characteristics as a result of the normalizing process, which isn’t necessarily the case with annealing.

Hardening

Create strong, hard steel through hardening. This process of heat treating metals takes three stages. The first two stages are typical of heat treatments, slow heating and soaking. Unlike normalizing or annealing, however, hardening uses a rapid cooling process. A plunge into water, brine or oil, known as quenching, helps produce some of the more unique characteristics of hardened metal.

First, this creates a particularly hard and strong metal. There are several alloys you can add to further increase its hardness. A material this hard is also brittle, so it isn’t as ductile or machinable as other heat treated metals.

Tempering

Choose tempering to balance some of the more extreme characteristics of hardening. This step in heat treating metals typically only occurs after the metal is already hardened. Tempering reduces brittleness and hardness in hardened metal.

The result is less internal stress and a more machinable product. In many cases, hardened metal is too hard and too brittle to be suitable for use in your industry. Tempering complements hardening to achieve the material you need for your products.

The process starts by reheated hardened material. At 212 degrees Fahrenheit, the tempering process begins. It continues until your material reaches the optimal hardness and strength. The cooling rate isn’t as important in tempering as it is in annealing or normalizing, but tempered materials are typically removed from the furnace and air cooled.