EVALUATION OF FRACTURE TOUGHNESS OF MEDIUM CARBON LOW ALLOY FORGED STEELS

Chandan B R, C M Ramesha, S.K.Rajendra, Sharanraj.V

Abstract: The purpose of the work is to determine the critical stress intensity factor K1C, according to ASTM E399 named as plane strain fracture toughness. The specimen used is chevron notchedCompact Tension specimen (CT-specimen) to create a fatigue crack by cycling the sample to minimum and maximum loads. Polyethylene glycol (PEG) H-(O-CH2-CH2)n-OH as quenchant was studied to investigate the fracture toughness (K1C) on the medium carbon low alloy forged steels in heat treated condition by hardening and step tempering process. The step tempering process of the 30% polymer quenched specimen results high fracture toughness compare to 10% polymer quenched and as forged samples. By heat treatment the microstructure of the steels is also varied and its effect on the fracture toughness is also observed. It has been found that fine grained structure results high fracture toughness. The microstructural examination of the samples were found to have justified reason for the increment recorded in some of the mechanical properties, as it displayed a high proportion of the martensitic phase.

Keywords: Fracture toughness (K1C), Polyethylene glycol (PEG), Microstructure.

DOI: https://doi.org/10.15623/ijret.2016.0525010