Heat treatment and materials based failures of critical shotgun parts and its preventation

The objective of this thesis was to improve the mechanical properties of AISI420, AISI 8620 and AISI 4140 materials used in some shotgun parts, which play a critical role in the operation of the mechanism, by applying heat treatment. These materials are widely used in a multitude of fields including defense, automotive, aerospace, mining, construction and agriculture. Critical parts used in hunting and sporting shotguns, which are exposed to high temperature and pressure, can be damaged due to the inappropriate microstructure of the material and the non-optimized heat treatments applied. Determining the optimum heat treatment parameters has a direct impact on the service life of the parts and therefore the shotguns, since the wrong choices in the process parameters applied during heat treatment cause premature damage to critical parts. In this study, the problems encountered in practice, such as the breakage and damage of manufactured and assembled parts during use, were addressed and the optimization of the heat treatments to be applied to prevent these errors was tried. Specific heat treatments were applied to the samples and parts produced by machining for the studies and experiments were carried out to examine the behavior of these parts used in shotguns under dynamic loads to increase fatigue strength, to improve the mechanical and microstructure properties of the material and the data obtained were compared. Hardness measurements, notch impact and tensile tests were performed and microstructure studies were carried out on the standard samples prepared in the study, with and without heat treatment. The results obtained showed that heat treatment significantly improved the mechanical properties of the parts and by determining the optimal parameters, the overall performance of the material can be improved. The data in this thesis provides information for heat treatment of selected materials and has the potential to extend the service life of these parts.