Name ONE property of steel that is tested by conducting a bending test on steel - NSC Mechanical Technology Fitting and Machining - Question 3 - 2018 - Paper 1

1. To relieve internal stresses in the steel, reducing the likelihood of cracks during machining.
2. To soften the steel, making it easier to work with in subsequent processes.

1. To require a wear-resistant surface while maintaining toughness within the core to withstand applied loads.
2. To create a hard case that offers high abrasion resistance, ensuring longevity in service.

Tempering is performed post-hardening to reduce the brittleness caused by the hardening process. It relieves internal strain, allowing the steel to regain some ductility while retaining its hardness, which enhances its overall toughness.

1. Heating temperature: The temperature should be controlled to avoid unwanted reactions in the steel.
2. Soaking time: The duration the steel is held at the target temperature must be adequate to achieve the desired properties.
3. Cooling rate: The rate at which the steel is cooled impacts its microstructure and resultant characteristics.

The hardening process involves heating steel to a temperature between 30 and 50°C above its critical temperature (Ac3). After reaching this temperature, the steel is held to allow the transformation of its structure. It is then rapidly cooled by quenching it in a medium such as water, oil, or brine, locking in a hard microstructure and enhancing its strength.