Determination of fracture toughness for uncarburized and carburized low carbon steel

Abstract

Surface hardening such as solid carburizing is well known in the engineering field and the basis of this action is to extend the life span of machines and other metal structures in order to cope with economic demand. The objective of this research is to study the fracture toughness in low carbon steel using two types of specimen: compact tension and bend specimens, with and without carburizing. For compact tension specimen, three types of testing methods were done: tensile test to get the maximum load, fatigue pre-cracking test to prepare the specimens with pre-crack within 2mm to 2.5mm, and fracture toughness test to complete the finding. On the other hand, there were also three types of testing methods done for bend specimen: flexural test to determine the maximum load, fatigue pre-cracking test to obtain the number of cycles needed to create a pre-crack and three point bending test to determine the fracture toughness. INSTRON 8802 universal testing machine was used to conduct all testing methods. Two different formulas to gain the fracture toughness were implemented for both types of specimens. The formulas were referred from ASTM E399 Guide Book for fracture toughness determination.