Analysis of the influence of velocity and time intervals for total force application in Rockwell hardness test cycles

The influence of key variables on hardness measurements, namely indenter velocity and geometry, dwell times, applied forces and temperature, has been thoroughly investigated in recent decades. The recent implementation of international definitions for the Rockwell hardness scale has heightened interest in understanding how these factors affect measurement outcomes. While these definitions and associated standards provide guidance on specific parameter ranges, the Rockwell hardness equation does not directly integrate these variables, making it necessary to empirically determine their sensitivity coefficients. This study specifically aims to identify the sensitivity coefficients related to two critical parameters: the velocity at which the final load is applied and the duration over which the force transitions from the preliminary value to the total force value. The analysis encompasses multiple Rockwell hardness scales, including B, C, 45 N, 30 N, and 15 N, across a range of hardness levels to deliver a comprehensive evaluation. Additionally, the influence of the duration of the total force application is evaluated for Rockwell C hardness. To conduct this analysis, we employed a Monte Carlo (MC) method in conjunction with Multiple Linear Regression (MLR) techniques, enabling a systematic simulation and assessment of variability in hardness measurements. The findings closely align with existing literature, thereby reinforcing the robustness and reliability of this study. By clarifying the relationship between these influential factors and hardness measurements, this research provides valuable insights aimed at enhancing the accuracy of Rockwell hardness testing practices.