The effect of Cu powder during Friction stir welding on microstructure and mechanical properties of AA3003-H18

, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Vol. 45, issue. 9 , 2014 , p. 3882-3891 Abnar, B ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology

2014

Abstract

Friction stir welding (FSW) was used to join 3003-H18 non-heat-treatable aluminum alloy plates by adding copper powder. The copper powder was first added to the gap (0.1 and 0.2 mm) between two plates and then the FSW was performed. The specimens were joined at various rotational speeds of 800, 1000, and 1200 rpm at traveling speeds of 70 and 100 mm/min. The effects of rotational speed, second pass of FSW, and direction of second pass also were studied on copper particle distribution and formation of Al-Cu intermetallic compounds in the stir zone. The second pass of FSW was carried out in two ways; in line with the first pass direction (2F) and in the reverse direction of the first pass...

Effects of heat input in friction stir welding on microstructure and mechanical properties of AA3003-H18 plates

, Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 25, Issue 7 , July , 2015 , Pages 2147-2155 ; 10036326 (ISSN) Abnar, B ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology

Nonferrous Metals Society of China 2015

Abstract

The non-heat-treatable AA3003-H18 plates were joined by friction stir welding (FSW) to achieve a proper joint by optimizing the welding parameters. For this purpose, the effects of heat input on microstructure and mechanical properties of the welded samples were investigated by changing the ratios of rotational speed (800-1200 r/min) to travel speed (40-100 mm/min) (ω/v). It was revealed that the grain growth rate was strongly increased with the increase of the heat input by rotational speed at constant travel speed, while the grain growth rate was slightly increased with the increase of the heat input by travel speed at constant rotational speed. Subsequently, hardness reduction was...

Groups and Spread of News in Social Networks

, M.Sc. Thesis Sharif University of Technology Abnar, Afra (Author) ; Safari, Mohammad Ali (Supervisor)

Abstract

Groups are important elements in social networks. First of all, because in real life human beings are members of different groups from the begining of their life till their death and even more. Moreover, groups’ influence on people and on other groups are undeniable. Thus studying groups in the context of social networks is of a great importance. In this Thesis, we are trying to make an effort in proposing a model for group membership. We discuss two models here: in the first model we consider a set of groups and a set of people, each of which want to gain membership of a subset of the groups’ set in order to maximize their payoff. We neglect the relationships between people and their...

Prepration of Software for Process Selection in Municipal Wastewater Treatment Plants

, M.Sc. Thesis Sharif University of Technology Kamalzadeh, Ladan (Author) ; Shyegan, Jalaloddin (Supervisor) ; Afra, Farrokh (Co-Advisor)

Abstract

A proper process selection has an important role in optimal operation of designed plants at exploitation time. The aim of this research is to provide software for the optimal process selection of municipal wastewater treatment plants in Iran which is a multi criteria optimization process. For this reason this project has been defined to establish a unique procedure for process selection aiming to help design engineers to find optimal process combinations. The main reasons of this case study include: special geology, the culture of people and economic conditions. Heretofore, numerous efforts have been done on optimal wastewater treatment process selection. But in most of them selection has...

Friction Stir Welding of 3000 Series Aluminum Alloy by Adding Cu Powder

, M.Sc. Thesis Sharif University of Technology Abnar, Behrouz (Author) ; Kokabi, Amir Hossein (Supervisor) ; Kazeminezhad, Mohsen (Co-Advisor)

Abstract

An increase in strength of friction stir welded (FSW) AA3003-H18 sheets is important, due to the reduction of mechanical properties in weld area such as heat affected zone and stir zone during welding. In this research, at first FSW was used to join 3003-H18 non-heat-treatable aluminum plates without adding copper powder. The specimens were joined at various rotational speeds (800, 1000 and 1200 rpm) and traverse speeds (40, 70 and 100 mm/min). In these cases, the effects of welding parameters on microstructure and mechanical properties were investigated. The average grain size of stir zone was in the range of 21.7-7.8 μm and the microhardness of them was 28-37 Hv. Then FSW was used to join...