Characterization of ultra-fine grained steel samples produced by high pressure torsion via magnetic Barkhausen noise analysis

2010-02-15
Bayramoglu, Sadik
Gür, Cemil Hakan
Alexandrov, Igor V.
Abramova, Marina M.
High pressure torsion (HPT) is one of the most widely used severe plastic deformation methods which enable to obtain a crack-free ultra-fine grained bulk sample. In the process, a disk-shaped sample is pressed between two anvils and deformed via surface friction forces by rotating one of the anvils. The aim of this study is to nondestructively characterize the variations in the deformation uniformity of the severely deformed disks. Various sets of low carbon steel samples were obtained by applying the constrained HPT process up to 6 turns. Magnetic Barkhausen noise (MBN) method was used in order to evaluate the samples in a nondestructive manner via a commercial system. The results were compared with those of metallographic examination, hardness measurements and X-ray diffraction (XRD). The initial stages of HPT revealed the effects of conventional plastic deformation on MBN; however with further straining, grain refinement caused increase in MBN signals.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Suggestions

Characterization of ultra-fine grained steel samples produced by high pressure torsion via magnetic barkhausen noise analysis
Bayramoğlu, Sadık; Gür, Cemil Hakan; Department of Metallurgical and Materials Engineering (2009)
High Pressure Torsion (HPT) is one of the most widely used severe plastic deformation methods which enable to obtain a crack free ultra-fine grained bulk material with improved mechanical properties like increased strength and toughness. In the process, a disc shaped sample is pressed between two anvils and deformed via surface friction forces by rotating one of the anvils. The aim of this study is to nondestructively characterize the variations in the deformation uniformity of the severely deformed steel d...
Investigation of polymerization of benzoxazines and thermal degradation characteristics of polybenzoxazines via direct pyrolysis mass spectrometry
Fam, Shahla Bagheri; Uyar, Tamer; Ishida, Hatsuo; Hacaloğlu, Jale (2012-10-01)
Polymerization of benzoxazines and thermal degradation mechanisms of polybenzoxazines were investigated using the direct pyrolysis mass spectrometry (DP-MS) technique. The benzoxazine structures were based on phenol and aniline and on bisphenol-A and methylamine or aniline. Polymerizations of the benzoxazines were carried out by curing them at elevated temperatures without addition of initiator or catalyst. DP-MS data showed the presence of chains generated by opposing polymerization reaction pathways indic...
Investigating the Effects of Subsequent Weld Passes on Surface Residual Stresses in Steel Weldments by Magnetic Barkhausen Noise Technique
Gür, Cemil Hakan; Batıgün, Caner; Çam, İbrahim (2016-03-01)
Variations of surface residual stresses with subsequent weld passes were investigated in API 5L X70 steel plates by the magnetic barkhausen noise (MBN) technique. The plates were welded by applying a number of different passes under fully clamped conditions. After each weld pass, the MBN signal and hardness distributions on the front and back surfaces of the plates were measured. A specific calibration procedure and setup were used for conversion of the MBN signals into elastic stress values. The results we...
Characterization of oil shales by high pressure DSC
Kök, Mustafa Verşan; Pokol, Gy. (1999-01-01)
Pressurised differential scanning calorimeter (PDSC) has been used to obtain information on the pyrolysis and combustion characteristics of oil shales. Two distinct exothermic peaks were identified in combustion experiments known as low temperature oxidation (LTO) and high temperature oxidation (HTO) reaction regions. The pyrolysis process of all studied oil shale samples showed one exothermic effect at each total pressure studied. Kinetic data were analysed by Roger & Morris and Arrhenius methods and the r...
Characterization of Ti-6Al-4V alloy foams synthesized by space holder technique
ESEN, ZİYA; Bor, Sakir (2011-03-25)
Ti-6Al-4V foams, biomedical candidate materials, were synthesized by powder metallurgical space holder technique as a result of evaporation of magnesium to achieve desired porosity content. Final products contained porosities in the range similar to 43-64% with an average macropore size between 485 and 572 mu m and a lamellar type Widmanstatten microstructure composed of alpha-platelets and beta-laths. Unlike the case of bulk Ti-6Al-4V alloy tested under compression loading, compression stress-strain curves...
Citation Formats
S. Bayramoglu, C. H. Gür, I. V. Alexandrov, and M. M. Abramova, “Characterization of ultra-fine grained steel samples produced by high pressure torsion via magnetic Barkhausen noise analysis,” MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, pp. 927–933, 2010, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/33074.