ENDURANCE INVESTIGATION OF NITRIDE FERRITIC STAINLESS STEEL SS439 UNDER TORSIONAL LOADING

• Main Author: Mohammad Latpi, Aliff Idham
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi Petronas 2013
• Subjects: TJ Mechanical engineering and machinery
• Online Access: http://utpedia.utp.edu.my/13764/1/Fyp2%20Dissertation_13021.pdf; http://utpedia.utp.edu.my/13764/

The author’s Final Year Project, which entitled Endurance investigation of Nitrided Ferritic SS439 Stainless Steel under Torsional Load. The purpose of the project is to investigate the effect of nitriding on the endurance of the nitride ferritic SS439 stainless steel under torsional loading condition. Nitriding is a thermochemical surface treatment for strengthen steel purpose. In the process, nitrogen is transferred and may diffuse into the steel at a certain temperature. Nitriding process recently becomes one of the attractive case-hardening processes for steel due to its metallurgical achievement like high surface hardness, improvement in fatigue life and increased wear resistance and anti-galling properties.The scope of this project includes application of nitriding process to the Ferritic Stainless Steel SS439 and endurance investigation for the samples before and after the nitriding process. In this project, low and high temperature gas nitriding has been applied to ferritic stainless steel SS439. Microstructure, hardness testing, and also fatigue testing has been done to the base, low and high temperature nitride SS439 to compare the phase changes happened to the SS439, and also to know the endurance of the material after treated with the nitriding process. The overall result shown that high temperature nitriding has higher efficiency than low temperature nitriding to the ferritic stainless steel SS439. In hardness test, hardness value for high temperature nitride is higher than low temperature nitride on SS439 on the sample surface and below the surface. The torsional fatigue testing proved that the endurance of nitride SS439 has been improved from the base SS439. High temperature nitride SS439 is higher endurance compared to low temperature nitride SS439 with cycle to failure up to 500000 under 10N loading.