Characterization of Mechanical Properties of ASTM A36 Steel After Cryogenic Treatment

The use of ASTM A36 steel through the cold bending process is often faced with material durability due to the occurrence of fine cracks in the process. Fine cracks can increase the risk of corrosion so in the long run it can reduce mechanical strength. The method of repairing steel structures by conventional methods (quenching) has disadvantages such as distortion and cracking in the steel, thereby reducing ductility and other mechanical properties. Deep cryogenic treatment (DCT) emerged as an alternative to overcome the shortcomings of conventional methods in a more effective way so that it can improve the structure of steel without causing distortion and cracking in the steel. This study focused on the analysis of ASTM A36 steels that have been DCT treated, with variations in immersion time (0, 12, 36, 60 hours) followed by characterization of mechanical properties (bending strength, tensile strength, and impact) and physical properties (microstructure). Cryogenic treatment significantly improves the mechanical capabilities of steel through granular refinement and microstructural homogeneity. Mechanical properties indicate that the sample treated for 60 hours shows the smallest grain size with the highest tensile strength (392.4 MPa), and the largest modulus of elasticity (1752.6 MPa). However, the ultimate strain decreased from 19.47% to 36 hours to 18.31% at 60 hours, corresponding to a relative reduction of approximately 5.96%. The best bending strength (892.81 MPa) is achieved after 12 hours. Impact toughness also increased with a longer duration, peaking at 290.08 J for 60 hours. These results emphasize the important role of cryogenic treatment in optimizing ASTM A36 steel for structural applications, where the balance between strength, rigidity, and toughness is critical. However, long soaking durations can lead to diminishing results, such as reduced ductility and bending strength, which require optimization of cryogenic parameters.