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Disorder Structure formation during plastic defroamtion of pure copper
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallernas gjutning.ORCID-id: 0000-0001-9315-7178
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallernas gjutning.ORCID-id: 0000-0003-2449-9232
2012 (Engelska)Ingår i: International journal of material science, ISSN 0973-4589, Vol. 7, nr 3, s. 169-182Artikel i tidskrift, Dagstidning (Refereegranskat) Published
Abstract [en]

The effect of the deformation process at 300˚C on the cast structure of pure copper is investigated. The temperature measurements during compression test are performed by a new experimental method developed earlier [1]. The deformed structure is studied with the aid of optical and transmission electron microscopy. Micrographs show the formation of deformed bands with high internal energy, due to many lattice defects. The strain energy calculations are based on an energy balance and the data obtain from micrograph studies performed by optical and transmission electron microscopy. It is found that there is a significant difference in the strain energy values obtained in the present work compared to the values available in the literature.  The strain energy values obtained in the band structure of the present work are 17.4% to 24% of the heat of fusion of Cu. Such high energy is sufficient to change the normal FCC structure to a disordered atomic structure in the highly deformed regions, during plastic deformation.

Ort, förlag, år, upplaga, sidor
Research Indian publication, 2012. Vol. 7, nr 3, s. 169-182
Nyckelord [en]
disorder structure, plastic defamation, copper
Nationell ämneskategori
Metallurgi och metalliska material
Forskningsämne
SRA - E-vetenskap (SeRC)
Identifikatorer
URN: urn:nbn:se:kth:diva-129570OAI: oai:DiVA.org:kth-129570DiVA, id: diva2:652974
Anmärkning

QC 20131031

Tillgänglig från: 2013-10-02 Skapad: 2013-10-02 Senast uppdaterad: 2024-03-18Bibliografiskt granskad
Ingår i avhandling
1. Microstructural Evolution In As-cast Alloys during Plastic Deformation
Öppna denna publikation i ny flik eller fönster >>Microstructural Evolution In As-cast Alloys during Plastic Deformation
2013 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The effect of deformation on microstructural changes in metals and alloys is the subject of considerable practical interest. The ultimate goal is to control, improve and optimize the microstructure and texture of the finished products produced by metal forming operations. The development in the subject field is remarkable but a more in-depth study could lead us to the better understanding of the phenomena.

 

In the present work microstructural evolution during the plastic deformation of as-cast pure metals and alloys is studied. An experimental method was developed to study the material behavior under the hot compression testing. This method was applied on the as-cast structure of copper, bearing steel, Incoloy 825 and β brass at different temperatures and strain rates. The temperature of the samples was measured during and after the deformation process. The microstructure of the samples was examined by optical microscopy and scanning electron microscopy (SEM). The microstructural evolution during deformation process was investigated by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The samples were subsequently subjected to electron microprobe analysis (EMPA) to investigate the effect of the deformation on the microsegregation of Mo, Cr, Si, and Mn.

 

It was observed that the temperature of the samples deformed at strain rates of 5 and 10 s-1 increases abruptly after the deformation stops. However, compression test at the lower strain rates of 1 and 0.5 s-1 revealed that a constant temperature was maintained in the early stage of deformation, followed by an increase until the maximum temperature was obtained. This temperature behavior can be explained by the microstructural evolution during the deformation process. Micrograph analysis revealed the formation of deformation bands (DBs) in highly strained regions. The DBs are highly effective sites for recrystallization. The interdendritic regions are suitable sites for the formation of DBs due to the high internal energy in these regions. EMPA indicated a tendency towards uphill diffusion of Mo in the DBs with increasing strain. The effect of strain on the dissolution of carbides in the band structure of bearing steel was investigated by measuring the volume fraction of carbides inside the band structure at different strain levels. The results indicate that carbide dissolution is influenced by strain. 

 

The microstructural evolution inside the DBs was studied as a function of several properties: temperature, internal energy, and microsegregation. Compression of β brass revealed that twinning is the most prominent feature in the microstructure. EBSD analysis and energy calculations demonstrated that the twinning is not due to a martensitic process but rather the order/disorder transition during the deformation process. The effect of heat treatment at Tc (650°C) prior to deformation on the microstructure of β brass was also investigated, which revealed a relationship between twin formation and the anti-phase domain boundaries

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2013. s. 44
Nyckelord
plastic deformation, compression test, recrystallization, deformation band, As-cast, microsegregation, carbide dissolution, disordered structure, order/disorder transformation, twining, steel, β brass, copper
Nationell ämneskategori
Teknik och teknologier
Forskningsämne
SRA - E-vetenskap (SeRC)
Identifikatorer
urn:nbn:se:kth:diva-133362 (URN)978-91-7501-926-0 (ISBN)
Disputation
2013-11-22, B2, KTH,Royal Institute of technology Brinellvägen23, Stockholm, 14:43 (Engelska)
Opponent
Handledare
Anmärkning

QC 20131104

Tillgänglig från: 2013-11-04 Skapad: 2013-10-31 Senast uppdaterad: 2022-10-25Bibliografiskt granskad

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Basirat, MitraFredriksson, Hasse

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