Pengaruh Konsentrasi Naoh sebagai Media Pendingin terhadap Sifat Mekanik Baja Karbon Menengah dengan Adanya Perlakuan Panas

Abstract

Have done a study on the influence of the concentration of NaOH as a cooling medium on the mechanical properties of medium carbon steel with a heat treatment. Heating medium carbon steel in the furnace heated up to 850 o C and then cooling rapidly carried to a solution of NaOH which has been varied concentrations (5%, 10%, 15%, 20%, 25%) and allowed to reach room temperature (27 o C). HRC hardness values of 9.4 and the tensile strength of 656.85 MPa for materials original, whereas for materials with the process of heat treatment and cooling cent with different concentrations of NaOH (5%, 10%, 15%, 20%, 25%) resulted in values hardness of 57 HRC, HRC 58.3, 58.5 HRC, 60 HRC, HRC 57.5 and the tensile strength of 728.50 MPa, 835.99 MPa, 987.26 MPa, 1035 MPa and 855 MPa for concentration different NaOH (5%, 10%, 15%, 20%, 25%). Oobservations of micro structure that looks to the material without heat treatment, namely the structure of ferrite and pearlite, while for materials with heat treatment process and the process of cooling the pearlite structure and martensit. From the test results, it can be concluded that the process of heat treatment and cooling process into a solution of NaOH hardness values and tensile strength increased, whereas at a concentration of 25% of the value of hardness and tensile strength decrease. The observation shows the microstructure of the visible changes in the structure of carbon steel medium which causes the hardness and tensile strength increased and the concentration of 25% NaOH microstructure shows the hardness and tensile strength decreased.