Strength Analysis of ST 41 Steel as Propeller Shaft with Quenching Heat Treatment and Tempering after Carburizing Carbon Media Variations

Steel (ST) 41 is a low carbon steel which can be used for propeller shafts because it is categorized as a carbon steel permitted by Indonesia Classification Bureau (BKI) with a tensile strength requirement of 400 to 800 N/mm ². The propeller shaft deteriorates due to its surface frequently rubbing against the bearings. Carburizing is a technique used to increase the surface hardness by heating the specimen in a closed container containing mixture of carbon and a catalyst. The main objective of the subsequent quenching and tempering processes is to increase toughness and ductility while eliminating residual stresses. The achieved results are based on tests conducted on ST 41 steel with a measured carbon layer thickness of 229.12 μm, namely coal carbon media. Based on the results of wear tests, coal carbon media possesses a minimum value of 6.38287E-05 mm ²/kg. In torsional testing, the maximum shear stress value for carbon media made from coconut shell charcoal is 429.79 MPa. When measuring hardness, coal carbon media has the highest value, which is 340.918 VHN and metallographic testing shows that pearlite was the main phase in coal carbon media. The media with the most carbon was coal carbon, which was 0.729% on the surface of the steel.