Effect of Kinetics and Microstructure on the Hardness of Alloy Steel
The effects of materials kinetics and microstructure on the hardness of alloy steel are commonly explored in fabrication projects. To understand the trends and ramifications of this relationship, it is important to first understand the definitions for each. Kinetics refer to the set of laws that describe the rates of change of a system of particles, as well as their position within that system. Microstructure is the as the small scale structure of a material and is composed of components such as grain size, porosity and dislocation density. Both factors have an effect on the hardness of a material and work in tandem to affect the resultant strength of the material.
The combination of the two factors can alter the hardness of a material significantly. Alloy steel is composed of multiple components including iron, carbon and other materials which affect the strength of the material but also the microstructure. The equilibrium between the elements is particularly important in studying the effects of kinetics and microstructure on hardness; as the interplay between components creates an adverse environment for subtle changes. In order for a clear relationship to be observed, the strength of the selected material must be adequately tested.
Stylus and microhardness testing can determine the hardness of alloy steel in a laboratory environment. As this is performed on a small sample, the size of the sample is important for performance accuracy. This is chiefly due to the need for the sample to meet the ASM standards for procedure verification and to provide a clear connection to the alloy steel tested. Through this process, the sample is able to receive a hardness number that offers an accurate, albeit subjective, representation of the strength of the sample.
The influences of kinetics and microstructure on the hardness of a sample of alloy steel can be observed through the comparison of sample hardness values. To evaluate the influence of either, specific parameters must be included. Firstly, is the ability of the test to accurately replicate the conditions of the alloy steel performance environment. This can be checked by ensuring adequate sample size and that the laboratory temperature during testing reflects what would be expected from the environment of the use-case.
At the same time, sample selection is important. Choosing alloys that are composed of varying amounts of the elemental components and evaluating their respective hardness levels at different depths offers a reliable way to understand the influence of the individual components and offers a direct comparison between the materials’ performance. This further enables comparison between different alloys and the influence of the microstructure on the resultant hardness of both test materials.
Multiple alloy hardnesses can be observed over time, allowing a clear relationship between kinetics and microstructure to be investigated. By recording the time taken, the rate of hardness alteration can be calculated as the components react to the differences in temperature and composition. Additionally, this provides variability that can be used to explore what parameters affect the rate of change, how quickly the process occurs, and the available timespans for the changes between the minimum and maximum levels of the tested sample.
Questions such as these provide an invaluable insight into the performance of alloy steel and can help to inform engineering decisions in production processes. While kinetic and microstructural alterations are relatively small on macroscopic scales, their very small nature is where the majority of their effects are observed. As such, understanding the relationship between the two is paramount for the reliable engineering of components for use in industry. Therefore, knowledge of the influence of kinetics and microstructure on the hardness of alloy steel is a crucial determinant of safety and reliability.
