Engineering Materials 1 Title: Objective: Hardness and Impact Tests of Steels To understand the mechanical properties of a metal (steel) particularly the relationship between hardness and impact Equipments: Rockwell Hardness tester and Chirpy Impact tester Samples: 1 . Gauge plate – about 0. 9%C As supplied (annealed): AS Water quenched: WAG Oil quenched: CO Water quenched + tempered: WAG + T Oil quenched + tempered: CO + T 2. Key steel – about 0. 4%C As supplied (annealed): AS Water quenched: WAG Procedures:
Samples have been heat treated using the following conditions: Systematizing at about COCO for 30 minutes, followed by water quench or oil quench. Some samples are then tempered at COCO for 1. Ah and allowed to cool in still air. The samples are ground/polished to remove the scales/oxide prior to hardness and impact tests. Results and Observation: Compare the hardness results with the impact values. Report (maximum 4 pages): Background & Theory Procedures Results & Discussion (see next page) Conclusion Make relevant comments about the experiment and the data ensuring that you answer the following in your comments: 1.
The relationship between heat treatment and toughness and hardness I. E. Briefly explain why the different heat treatments give different toughness and hardness values. What do you think is the difference between hardness and toughness? Explain the general relationship between hardness and toughness. 2. Relate the observed fracture surfaces of the samples to the Chirpy Impact results and in terms of brittle or ductile fractures. Report due: Friday, 6 Seep 2013 by 4 pm (drop box WAS Bldg Level 3)