18-10-2014, 12:17 PM
Abstracts: Our project focuses on the failure analysis of grinding jib which is a sand casted part and is made up of K.M.D. material. Grinding jib is used for crushing stones in impact crusher. It is used in assembly with the crusher ring and impact hammer. It is heat treated to improve its hardness and toughness. Hardening, quenching and tempering heat treatment processes are used. We carried out the analysis for the casting defects by using Ultrasonic test and Magnetic Particle Inspection and then we carried out the analysis for heat treatment defects by checking the rate of heating of the furnace, the quality of quenching medium and zone wise temperature difference of the furnace. We studied the microstructure and the reason for the failure of the grinding jib was found to be cracks formed by Retained Austenite (RA) which is unstable in nature. Solution to the problem is that tempering process should be carried out immediately after the hardening process.