The Effect of tempering temperatures on a fatigue of AISI 4130

• Main Author: Norakmar, Jamal
• Format: Thesis
• Language: English; English
• Published: 2013
• Subjects: T Technology (General); TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.utem.edu.my/id/eprint/14962/; http://library.utem.edu.my:8000/elmu/index.jsp?module=webopac-d&action=fullDisplayRetriever.jsp&szMaterialNo=0000085422

Mechanical properties of material can be changed by heat treatment processes without changing its shape. In this research, a relationship between various tempering temperature and fatigue life of AISI 4130 steel has been evaluated. This steel is a low alloy steel containing molybdenum and chromium as strengthening agents. The material has been hardened, followed by tempering with three tempering temperatures, 100 °C, 350 °C and 700 °C. Fatigue tests under rotating bending fatigue testing machine has been carried out to estimate the effect of tempering temperature on its fatigue life. The fatigue life of these materials has been studied as a function of the tempering temperatures. Microstructure of the materials has been analyzed using Optical Microscope (OM). A Stereo Microscope has been used to observe surface fractures on the material. The result show that increasing the tempering temperature from 100°C to 350°C has increased the fatigue life of the heat treated material compared to non-treated material. But, increasing the tempering temperature furthermore to 700 °C has decrease its fatigue life lower than the non-treated material. From microstructure analysis, changes in fatigue life of this material are due to the changes in its microstructure as a result of hardening and tempering processes. Besides that, the surface fractures are different between each others as a result of different tempering temperatures. The difference that can be distinguished is the size of the fast fracture zone. As the size of the fast fracture zone is decreases, the fatigue life is also decreases.