EFFECT OF TEMPERATURE VARIATION IN PROCESS SELF TEMPERING AND VARIATION OF HOLDING TIME IN TEMPERING PROCESS PROPERTIES OF STELL AISI 4140

The purpose of this study was to determine the mechanical properties of AISI 4140 steel by using a variation of the holding time at the tempering process and temperature variations on the process of self-tempering. In this study, first the material is heated at a temperature of 850° C with a hold time later at 14 and 28 minutes, cooling media with Oil Type SAE 20 In the process of tempering steel is reheated to a temperature of 200° C with a hold time of 30 and 120 minutes. As for the process of self-tempering, the steel heated at 850° C with a hold time of 14 and 28 minutes and then cooled with SAE 20 oil media, during the process of cooling the temperature to be achieved is 200° C, 400° C and 600° C. The process of tempering with the variation of the holding time has a value of 50.1 HRC hardness largest holding time of 120 minutes, while the largest hardness value on the process of self tempering the temperature variation is 29.68 HRC at a temperature of 200° C. Largest toughness values during the tempering process is 0.341 (J/mm 2) with a hold time of 120 minutes, while at the largest self-tempering toughness at a temperature of 600° C with a value of 0.375 (J / mm 2). Largest corrosion rate during tempering is 0.055 (mpy) with a hold time of 30 minutes, whereas during the process of self-tempering largest corrosion rate at a temperature of 400° C with a value of 0.0388 (mpy).