This process describes a specific heat treatment applied to a medium-carbon, low-alloy steel. The designation “4140” denotes a steel alloy known for its strength, toughness, and fatigue resistance. Annealing at 1600F (871C) softens the material, relieving internal stresses and refining the grain structure. This prepares the steel for subsequent hardening. The rapid cooling achieved through oil quenching then transforms the microstructure, significantly increasing hardness and strength.
This combination of annealing and oil quenching allows for tailored mechanical properties, making the steel suitable for demanding applications. The resulting enhanced strength, hardness, and fatigue resistance are crucial in components requiring durability under stress, such as gears, shafts, and other critical structural parts. Historically, this controlled thermal processing has been essential for advancing engineering and manufacturing capabilities across various industries, including automotive, aerospace, and tooling.
