A Novel Approach to Structure Modification of Brasses by Combination of Non-equilibrium Heat Treatment and Friction Stir
- PDF / 7,362,632 Bytes
- 8 Pages / 593.972 x 792 pts Page_size
- 80 Downloads / 141 Views
TRODUCTION
FRICTION stir processing (FSP) has recently been developed based on the fundamentals of friction stir welding method for modifying the surface structure and properties of metals and alloys.[1] During FSP, a rotating non-consumable tool inserts into the material and then traverses along the processing line.[2] It can be employed in two different ways of processing with or without using reinforcements. In the first approach, ceramic particles are injected during FSP into the processed material.[3] In the second way, no reinforcements are injected, and the properties of the processed materials change by only dynamic restoration mechanisms such as dynamic recrystallization (DRX).
AKBAR HEIDARZADEH is with the Department of Materials Engineering, Azarbaijan Shahid Madani University, P. O. Box: 53714161, Tabriz, Iran. Contact e-mails: [email protected], [email protected] ALI CHABOK and YUTAO PEI are with the Department of Advanced Production Engineering, Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands. VOLKER KLEMM is with the Institute of Materials Science, Technische Universita¨t Bergakademie Freiberg, Freiberg, Germany. Manuscript submitted November 13, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS A
Friction stir processing of Cu–Zn alloys (brasses) has attracted many attentions recently.[4–8] This is because of the fact that FSW is a solid state process and most of the problems associated with the fusion processes of Cu–Zn alloy systems such as zinc evaporation, color change, gas porosity, shrinkage porosity, distortion, micro and macro segregations, dendritic structures, etc. can be overcome. A few methods have been suggested so far to modify the final microstructure and mechanical properties of the FSPed brasses, which can be divided into three categories. In the first category, low heat input conditions were used to refine the grain structure.[9–11] For example, Sun et al.[9] obtained a processing map for the friction stir welding (FSW) of commercial 2-mm-thick single phase Cu-30Zn brass alloy plates. They reported that the average grain size ranged from 6.4 to 9.6 lm depending on the different welding conditions, much smaller than the grain size (28.2 lm) of the base metal. However, using low heat input conditions for FSP of brasses causes more defects and reduced mechanical properties. It is notable that in addition to the grain refinement of the brasses, higher dislocation density with tangle structures, lower texture intensity, and larger values of Taylor factor have been reported as other reasons for improved mechanical properties after FSP/FSW.[6,7] The second category refers to the methods that use cooling media during or after FSW/FSP.[12–14] For instance, Xu et al.[14] have used liquid CO2 as the cooling
medium during the FSW of 70/30 brass plates. Their results showed that the rapid cooling could prohibit both recovery and static recrystallization, which resulted in enhance
Data Loading...
