Fatigue strength is one of the most important properties that affect on the life of machine part. In the first part is presented the basic construction of hydraulic grapple, following is represented considered machine part; shaft of hydraulic grapple. Work has focus on heat-treatment steels, their chemical composition and the influence of alloying elements on heat treatment. In work is represented process of heat treatment of low carbon steel. Afterwards is an analysis of the current material and the process of selecting a new material for a dynamically loaded machine part. For known current loads and aplication, a suitable candidate is selected for comparison with the current one. Test samples of both materials were prepared for mechanical tests. Mechanical tests of fatigue strength, hardness, impact and fracture toughness, and fracture surface analysis were then corrected. Based on the results, we make conclusions on which material is more suitable for current application. We have concluded that the new material has better all measured mechanical properties and is suitable for test installation. We also checked the economic aspect of replacing the material, which is proportional to the improvement in mechanical properties.
|
