A study on improving torsional power of carbon steel St.37 with 800 ºC heating and fresh water quick cooling
The steel St.37 is often used as a machine component or as a shaft material, because it is relatively inexpensive and easily heat treated. Heat treatment of steel St.37 is used to get the desired strength change. It means, before being used in construction techniques, the resistance of steel to external loads as a technical material is very important to know. Due to the resistance of external loads, for example in the form of twisting on the shaft or engine components in appropriate technology is very common. The change of steel strength by the external load is carried out by heat treatment, which through the heating process to a certain temperature and the cooling process using certain media and with a certain cooling speed as well. This study examines how much the standard steel torsion strength (St.37) is increases compared to the same type of steel after going through the 800 ºC heat treatment process with rapid cooling using fresh water. The testing of this study is carried out on the Torsion Measuring Testing Machine Model N-50, together with the fourth semester students, in the material and metrology testing laboratory of the Bali State Polytechnic Mechanical Engineering Department. As a result, steel St.37 hardening through 800◦C heating and cooled quickly using fresh water, compared with standard steel (St. 37), it seen from the test results, namely: Maximum steel twist stress St.37 Standard: 503.7021855 N.mm-2 at the maximum torsional moment is 24.6 Nm, whereas, the maximum torsional stress of St.37hardening steel: 697.8735409 N.mm-2 at a maximum torsional moment of 35.4 Nm. The elasticity modulus (G) of each specimen after being calculated using relevant formulas, is obtained: G (St.37 standard) = 4205.500677 (N.mm-2) G (St.37 hardening) = 1335.750379 (N.mm-2).