Thesis Defense - Orhun Tugay (MSME)

İbrahim Orhun Tugay - M.Sc. Mechanical Engineering

 Assoc. Prof. Dr. Güney Güven Yapıcı – Advisor

Date: 15.01.2021

Time: 13:30

Location: This   meeting   will   be   held   ONLINE.   Please   send   an   e-mail to gizem.bakir@ozyegin.edu.tr in order to participate in this defense.

The Effects Of Roller Burnıshıng On Surface Integrıty And

Mechanıcal Propertıes Of Duplex Snd 316L Staınless Steels

Thesis Committee: 

Assoc. Prof. Dr. Güney Güven Yapıcı, Özyeğin University 

Asst.Prof. Dr. Polat Şendur, Özyeğin University 

Asst.Prof. Dr. Mehmet İpekoğlu, Turkish-German University

Abstract:

Roller burnishing (RB) or deep rolling is a mechanical surface treatment method to enhance the surface integrity of manufactured components which affects component's performance. Although there are some valuable researches on the effects of RB on different materials, there is no comprehensive investigation about roller burnishing of duplex stainless steel (DSS) and 316L stainless steel, in a comparative manner.

The main purpose of the present thesis is to reveal the effect of RB on surface integrity and mechanical properties of duplex and 316L stainless steel. In order to understand the effect of RB parameters on surface integrity, Taguchi L9(34) experimental design method was utilized. The changes in microstructure, surface microhardness, and surface roughness were measured after the RB process and the optimized parameters for the maximum surface microhardness (condition H) and the minimum surface roughness (condition R) were determined. It was shown that burnishing created a refined surface layer up to 0.6 mm and 0.8 mm, enhanced surface microhardness to 118%, and 147%, and reduced surface roughness to 52%, and 40% of the initial values, respectively for DSS and 316L.

Ambient temperature tensile tests were performed, and the results revealed no notable improvement in yield and tensile strengths after the RB process. On the other hand, significant enhancements were observed in the cyclic performance after the burnishing process. Subsequently, the results of high cycle fatigue (HCF) tests revealed that the cyclic performance of the burnished sample with H condition was significantly higher than those of both unburnished and condition R samples, especially at low-stress amplitudes. Besides, fracture surface analysis exposed the restriction of crack initiation and propagation in the hardened surface layer. Subsequently, the results of reciprocating wear tests unveiled a significant increase in wear resistance after the burnishing process. It was detected that the condition H samples have superior wear resistance in hard abrasive cases, while condition R samples are more resistive in soft abrasive conditions.

Bio:

Ibrahim Orhun Tugay was born in 1994 in Istanbul. He received his B.Sc. in Mechanical Engineering from Ozyegin University, Turkey in 2017 and he is currently seeking an M.Sc. degree in Mechanical Engineering at Ozyegin University. His research interests at the MEMFIS group of Ozyegin University mainly concentrates on the inuence of the roller burnishing process on stainless steel.