br Experimental procedure br Response surface methodology

Experimental procedure
Response surface methodology Response surface methodology (RSM) is an approach to determine the relationship between various process parameters with the various machining criteria and explore the effect of these fluorescent probes process parameters on the coupled responses, i.e., tensile strength and microhardness. The equation of the second-order polynomial response surface methodology is given belowwhere Yu is response; x (1,2, …,k) is the coded level of k quantitative variables;b0 is the constant term, where b, b, and b are the coefficients of the linear equation. The nonlinear form of Eq. (1) was converted into a linear form through the logarithmic transformation. It was used to develop response surface regression form. To create the calculation method, a software package mini Tab was used to find out the coefficients of mathematical modeling based on the response surface regression form. The level of parameter chosen for the trial was given in Table 1. Twenty experiments are carried out according to the central composite design. The experimental design matrix and results were given in Table 2.
Mathematical modelling The mathematical relationship obtained for analyzing the influences of the various dominant tensile parameters on the tensile strength (TS) criteria is given by The mathematical relationship for correlating the microhardness (Ha) and the considered process variables was obtained as follows
Results and discussion
Analysis of response optimization Based on the developed second – order response surface equations, i.e., Eq. (2), for correlating the various process variable effects with the tensile strength and hardness optimality searches can be obtained. This is carried out to determine the optimal combination of the tensile parameters and their combined effect on the desired response criteria [12]. The optimality search model for the different process variable position for maximizing the tensile strength and microhardness values is based on response surface methodology. Fig. 8 shows that solutionizing time is 3 h, aging temperature is 170 °C, and aging time is 5 h. The most favorable values of tensile process parameters for different aging criteria are also shown in Table 6. Tensile strength and microhardness can achieve to 263 Mpa and 67.14, respectively, through the optimized parametric combination.
Conclusions