Steel St.37 is a widely used metal in industry. Lightweight, corrosion resistant, and good heat conductor cause aluminum is selected to be one of the materials to make a machine component such as alloy wheels, pistons, and other machine components. The high number of aluminum usage in the manufactureindustry is inseparable from foundry technology. Quenching test is using Furnace test and cooled with water and SAE 400C lubricant oil. Testing 1: 2 pcs Stainless steel specimens are heated at 400C to 8000C temperature obtained 33 minutes result of red color is then blue then cooled with water ash To-brown. Test 2: 2 pcs Stainless steel specimens were heated at a temperature of 6000 C to 8000 C in 5 minutes the result of red-colored blue was then cooled with water from gray to brown. Test 3: 2 pcs Stainless steel specimens were heated at a temperature of 7000C to 8000C, obtained within 2 mins of reddish blue then cooled with water of gray to brown. Testing 4: 2 pcs Stainless steel specimens were heated at temperatures of 400C to 8000 C obtained 33 minutes of blue later in color cooled with black material lubricating oil. Testing 5: 2 pcs Stainless steel specimens were heated at a temperature of 6000C to 8000 C in 5 minutes the result of blue color was subsequently cooled with lubricating oil obtained from the color of black material. Testing 6: 2 pcs Stainless steel specimens were heated at a temperature of 7000 C to 8000C, obtained in minutes of reddish blue later on cooled with lubricating oil obtained by color from black material.

Keywords : Characteristics, Steel St.37, Temperature, Time, Furnace.