Tempering Steel in the Manufacturing Process – Part 1

automotive shocks

Steel is used in products from almost every industry and goes through a variety of heat treat processes prior to reaching the end product manufacturing stage. Tempering is a heat treat process used to reduce the frailness in hardened steel and remove internal strains resulting from other metal treatment processes, such as hardening and quenching. While the tempering process is ancient, dating back to at least 1200 to 1100 BCE, tempering is still one of the most advanced methods of strengthening steel.

Hardening steel involves the use of furnaces to heat up beyond its upper critical temperature, usually between 800 and 900°C. At these temperatures, changes in the chemical composition of the metal take place. Quenching the heated steel in water, oil, or another suitable liquid to quickly bring the temperature down creates further changes to the metal.

Heat treatment changes the chemical composition of the metal’s surface. Heating steel to its critical temperature creates austenite, a metallic alloy combining carbon and iron that gives steel its strength. Quenching creates martensite, a type of steel with a hard, crystalline needle-like structure that can cause brittleness. The tempering process reduces the brittle qualities of martensite by changing the needle-like structures to bushy-like structures that are less apt to break, thereby improving the quality of steel that will be used to manufacture the end product.

When looking at the automotive industry, the use of tempered steel is common in the suspension system of vehicles. The components that make up the suspension, like spring clips, need to maintain durability when going over dense terrain. The spindle found in the suspension system is also tempered and holds the hub of the wheels. This spindle connects to both the upper and lower arms for control of the load placed on the suspension.

The tempering of steel is performed in a heat treat furnace. The tempering furnace heats the steel to the appropriate temperature and holds it for a specified period of time. Lindberg/MPH manufactures tempering furnaces that are designed to meet customer’s specific process requirements. In the next section, temperature will be reviewed as a key factor in the tempering process.

Read about the benefits and features on the Lindberg/MPH website. Be sure to follow Lindberg/MPH on both Facebook and LinkedIn for more information and product updates! Check back next month for part 2 of this blog series.