Articles By D. Scott MacKenzie, Ph.D., FASM
In this issue, a discussion of the mechanism of quench oil, focusing on oxidation, thermal degradation, contamination, and additive depletion.
Aggressive grinding can result in thermal damage and potential cracking of a ground part, but methods exist to detect grinding burns and cracks.
Factors that affect hardenability and the rate of austenite transformation — carbon content, grain size, and alloying elements — can be used to calculate hardenability for comparing alloy grades.
A method is described to either calculate the hardness in a component given the quenchant used or to select a quenchant to achieve a desired hardness at the core or surface of a part.
Machining and fixturing prior to heat treatment are among the many potential sources for distortion and residual stress.
Surface engineering draws upon chemistry, material science, metallurgy, tribology, and biology to enhance surface properties for improving parts.
Manufacturing a component is oftentimes extremely complex, even when that component seems as simple as a bearing.
Carburizing is a widely used, effective technique to increase surface hardness of steel used in gears, and achieve a compressive residual stress. There are several methods, and hotter isn’t always better.
The impact of proper cleaning and rinsing on part quality prior to heat-treating is critical to the surface finish and overall quality of the finished gear.
In order to truly understand the distortion that can occur during heat treatment, it’s important to understand the issues of prior microstructure and hardenability.
Some think coolants or other contamination do not harm the quenchant. This perception couldn’t be farther from the truth.
This installment explores the chemistry of oil quenchants and the effects of additive packages on quenching performance, to be followed in February by a discussion of base oils.
This installment explores the chemistry of base oils, particularly as they affect quenching performance, to be followed in March by a discussion of quench oil oxidation.
Quench oil oxidation is a serious problem, but it can be overcome with appropriate corrective actions listed here.