STATISTICAL ANALYSIS OF THE RESULTS OF DOUBLE HARDENING HEAT TREATMENT ON ST40 STEEL USING THE T-TEST METHOD AND MULTIPLE LINEAR REGRESSION

Abstract

Mild steel is a material used for construction and machine components, the advantages of Mild Steel are soft, relatively low hardness, easy to weld and can be carried out machining processes. The mechanical properties of steel play an important role in determining the maximum limit of mechanical properties and life time of the construction and components of the machine. In order to produce optimal low carbon steel hardness, experimental design is needed in order to obtain valid experiment results. Based on statistical analysis using the multiple linear regression sample t-test method. The research data were analyzed using statistical correlation and comparative analysis using SPSS 2016 software. The regression equation using quenchant water was Y= 0.184 + 0.208x1 - 0.057x2, with the F test value being sig = 0.000 < 0.05 with the coefficient of determination shown by R square = 0.593 . The regression equation using oil quenchant is Y= 0.164 + 0.125 x1 - 0.036 x2, with the F test value being sig = 0.000 < 0.05 with the coefficient of determination shown by R square = 0.69. It can be concluded that the comparison of hardness values ??using quenchant water and oil obtained a significance level for the overall double hardening and tempering data > 0.05 in the sense that there is no significant difference in the hardness value of ST40 steel using water and oil cooling media.