Thesis Defense - Mustafa Mısırlı (MSME)

Mustafa Mısırlı- M.Sc. Mechanical Engineering

Assoc. Prof. Güney Güven Yapıcı- Advisor

Aging Response of AZ Series Magnesium Alloys After Thermo-mechanical Processing

Date: 20.08.2019

Time: 13:00

Location: AB1 510

Thesis Committee: 

Assoc. Prof. Güney Güven Yapıcı,  Özyeğin University

Asst. Prof. Altuğ Melik Başol,  Özyeğin University

Asst.Prof. Alpay Oral, Yıldız Technical University

Abstract

The current study aims to investigate the effect of thermo-mechanical treatment utilizing both aging and stress aging on the mechanical characteristics of warm rolled AZ31 magnesium alloy with inspecting the relationship between the microstructure evolution, tensile properties, and fracture morphology.

The individual contributions of conventional and stress aging on the tensile properties and microstructure of the warm rolled AZ31 magnesium alloy are investigated in detail. The aging treatments were conducted at different temperatures of 120˚C and 180˚C for various durations ranging from 1h to 48h. Annealed AZ31 magnesium alloy was used as the as-received slab and homogenization treatment was conducted at 400˚C for 3h before the rolling process.

Inspection of tensile test results revealed that the ultimate tensile strength (UTS) of the as-received AZ31 after 24h aging at 120˚C increased up to 300 MPa with a 2% reduction in failure strain. Whereas the yield strength (YS) of the specimen aged at 180˚C for 24h decreased to 190 MPa with the improvement of ductility near to 14% and the UTS up to 285 MPa. Also, stress aging at 120 ˚C for only 1h after rolling, increased the yield strength of the as-received sample to over 240 MPa.

Microstructural observations displayed that the grain growth initially diminished the strength of rolled samples while improving the ductility. This is followed by the nucleation of recrystallized grains which improves the ultimate strength with satisfactory ductility as compared to the rolled specimens. Furthermore, the fracture morphology of stress aged samples presents nucleation-controlled fracture mechanisms with deeper void structures as a common ductile characteristic.

Bio

Mustafa Misirli was born in 1988 in Keşan. He received his B.Sc. in Mechanical Engineering from Dokuz Eylül University, Turkey in 2012 and he is currently pursuing the M.Sc. degree in Mechanical Engineering at Ozyegin University. His research interest mainly includes the mechanical properties of light alloys.