scholarly journals Intragranular ferrite morphologies in medium carbon vanadium-microalloyed steel

2013 ◽  
Vol 49 (3) ◽  
pp. 237-244 ◽  
Author(s):  
A. Fadel ◽  
D. Glisic ◽  
N. Radovic ◽  
D. Drobnjak
Keyword(s):  
Grain Boundary ◽  
Low Temperatures ◽  
Acicular Ferrite ◽  
Microalloyed Steel ◽  
Isothermal Treatment ◽  
Medium Carbon ◽  
Intragranular Ferrite ◽  
Micro Alloyed Steel ◽  
Scanning Electron ◽  
Grain Boundary Ferrite

The aim of this work was to determine TTT diagram of medium carbon V-N micro-alloyed steel with emphasis on the development of intragranular ferrite morphologies. The isothermal treatment was carried out at 350, 400, 450, 500, 550 and 600?C. These treatments were interrupted at different times in order to analyze the evolution of the microstructure. Metallographic evaluation was done using optical and scanning electron microscopy (SEM). The results show that at high temperatures (? 500?C) polygonal intragranulary nucleated ferrite idiomorphs, combined with grain boundary ferrite and pearlite were produced and followed by an incomplete transformation phenomenon. At intermediate temperatures (450, 500?C) an interloced acicular ferrite (AF) microstructure is produced, and at low temperatures (400, 350?C) the sheave of parallel acicular ferrite plates, similar to bainitic sheaves but intragranularly nucleated were observed. In addition to sheaf type acicular ferrite, the grain boundary nucleated bainitic sheaves are observed.

THE CHANGE IN THE CHEMICAL COMPOSITION AND TOUGHNESS OF API 5L-X70 WELDS BY ADDITION OF TITANIUM

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1209-1216 ◽  
Author(s):  
BEHROOZ BEIDOKHTI ◽  
AMIR HOSEIN KOUKABI ◽  
ABOLGHASEM DOLATI ◽  
PENG HE
Keyword(s):  
Grain Boundary ◽  
Weld Metal ◽  
Acicular Ferrite ◽  
Titanium Content ◽  
Weld Deposit ◽  
Steel Weld Metal ◽  
Metal Properties ◽  
Api 5L X70 Steel ◽  
The Relationship ◽  
Grain Boundary Ferrite

The objective of this work was to study the influence of titanium variations on the API 5L-X70 steel weld metal properties. The relationship between microstructure and toughness of the weld deposit was studied by means of full metallographic, longitudinal tensile and Charpy- V notch tests on the specimens cut transversely to the weld beads. The best combination of microstructure and impact properties was obtained in the range of 0.02-0.05% titanium. By further increasing of titanium content, the microstructure was changed from a mixture of acicular ferrite, grain-boundary ferrite, Widmanstätten ferrite to a mixture of acicular ferrite, grain-boundary ferrite, bainite and ferrite with M/A microconstituent. Therefore, the mode of fracture also changed from dimpled ductile to quasi-cleavage. Titanium-base inclusions improve impact toughness by increasing the formation of acicular ferrite in the microstructure. The amount of manganese in inclusions was decreased with addition of titanium to the weld metal.

Acicular ferrite morphologies in a medium-carbon microalloyed steel

2001 ◽  
Vol 32 (9) ◽  
pp. 2187-2197 ◽  
Author(s):  
I. Madariaga ◽  
I. Gutierrez ◽  
H. K. D. H. Bhadeshia
Keyword(s):  
Acicular Ferrite ◽  
Microalloyed Steel ◽  
Medium Carbon ◽  
Carbon Microalloyed

The Effect of Austenite Grain Size on the Growth of Different Ferrite Morphologies in a Nb-Microalloyed Steel

2009 ◽  
Vol 289-292 ◽  
pp. 109-117 ◽  
Author(s):  
Mohamad Esmailian
Keyword(s):  
Growth Rate ◽  
Grain Size ◽  
Grain Boundary ◽  
Microalloyed Steels ◽  
Growth Behaviour ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Intragranular Ferrite ◽  
Austenite Grains ◽  
Grain Boundary Ferrite

The effect of austenite grain size on the austenite to ferrite transformation temperature and different ferrite morphologies and growth behaviour in one Nb-microalloyed (HSLA) steel has been investigated. Three different austenite grain sizes were selected and cooled for obtaining austenite to ferrite and growth behaviour of ferrite. Moreover, samples with specific austenite grain size have been quenched, partially, for investigation of the microstructural evolution. The optical microscopy observation suggested that the nucleation site of ferrite is on edge and inside of austenite grains in Nb- microalloyed steels. Micrographs of different ferrite morphologies show that at high temperatures, where diffusion rates are higher, grain boundary ferrite nucleates both at the edge and corner of austenite grains and grows into both austenite grains. As the temperature is lowered and the driving force for ferrite formation increases, intragranular sites inside the austenite grains become operative as nucleation sites and suppress the grain boundary ferrite growth. With more undercooling,intragranular ferrites are seen to nucleate and grow more extensively , indicating the beginning of displacive transformation. Furthermore, growth rate of intragranular ferrite shows that by increasing of austenite grain size, the growth rate of intragranular ferrite increases extensively and growth rate of grain boundary ferrite decreases. The growth kinetics of grain boundary ferrite shows that this transformation is controlled by the diffusion of carbon in the austenite ahead of the interface.

Effect of Nb on Microstructure Evolution of Coarse-Grained Heat-Affected Zone with Large Heat Input Welding

2011 ◽  
Vol 284-286 ◽  
pp. 1174-1179 ◽  
Author(s):  
Xue Li Tao ◽  
Kai Ming Wu ◽  
Xiang Liang Wan
Keyword(s):  
Grain Boundary ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Acicular Ferrite ◽  
High Strength ◽  
Coarse Grained ◽  
Granular Bainite ◽  
Low Alloy Steels ◽  
Alloy Steels ◽  
Grain Boundary Ferrite

The effect of Nb microalloying on microstructure transformation of coarse-grained heat-affected zone of high strength low alloy steels were investigated utilizing different heat input welding simulation. For the low-Nb steel, the microstructures of coarse-grained heat-affected zone mainly consisted of acicular ferrite, bainite and grain boundary ferrite for small heat input welding; the amount of acicular ferrite decreased whereas grain boundary ferrite, polygonal ferrite and pearlite increased with increasing heat input. In constrast, for the high-Nb steel, granular bainite was the dominant microstructure. The formation of granular bainitic microstructure was associated with the solid solution of Nb, which suppressed ferrite transformation and promoted the formation of granular bainite. The hardness of coarse-grained heat-affected zone increased with increasing Nb content, and decreased with decreasing heat input, which was attributed to the microstructural change.

scholarly journals Structure and Strength of Isothermally Heat-Treated Medium Carbon Ti-V Microalloyed Steel

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1011
Author(s):  
Stefan Dikić ◽  
Dragomir Glišić ◽  
Abdunnaser Fadel ◽  
Gvozden Jovanović ◽  
Nenad Radović
Keyword(s):  
Dislocation Density ◽  
Yield Strength ◽  
Microalloyed Steel ◽  
Isothermal Transformation ◽  
Compressive Yield Strength ◽  
Medium Carbon ◽  
Intragranular Ferrite ◽  
Heat Treated ◽  
Final Microstructure ◽  
Compressive Testing

Isothermal transformation characteristics of a medium carbon Ti-V microalloyed steel were investigated using light microscopy, scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and by uniaxial compressive testing. Samples austenitized on 1100 °C were isothermally treated in the range from 350 to 600 °C and subsequently water quenched. The final microstructure of the samples held at 350 °C consisted of bainitic sheaves and had compressive yield strength, approximately from 1000 MPa, which is attributed to high dislocation density of low bainite. At 400 and 450 °C, acicular ferrite became prevalent in the microstructure. It was also formed by a displacive mechanism, but the dislocation density was lower, leading to a decrease of compressive yield strength to approximately 700 MPa. The microstructure after the heat treatment at 500 °C consisted of coarse non-polygonal ferrite grains separated by pearlite colonies, principally dislocation free grains, so that the compressive YS reached a minimum value of about 700 MPa. The microstructure of the samples heat-treated at 550 and 600 °C consisted of pearlite and both grain boundary and intragranular ferrite, alongside with some martensite. After 600 s, austenite became stable and transformed to martensite after water quenching. Therefore, the presence of martensite increased the compressive YS to approx. 800 MPa.

Ultrastructure of the soil fungus, Geomyces pannorus

1984 ◽  
Vol 42 ◽  
pp. 738-739
Author(s):  
J. A. Traquair ◽  
E. G. Kokko
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fine Structure ◽  
Low Temperatures ◽  
Soil Fungus ◽  
Organic Soils ◽  
Anatomical Studies ◽  
Transmission Electron ◽  
Electron Microscopical ◽  
Scanning Electron

With the advent of improved dehydration techniques, scanning electron microscopy has become routine in anatomical studies of fungi. Fine structure of hyphae and spore surfaces has been illustrated for many hyphomycetes, and yet, the ultrastructure of the ubiquitous soil fungus, Geomyces pannorus (Link) Sigler & Carmichael has been neglected. This presentation shows that scanning and transmission electron microscopical data must be correlated in resolving septal structure and conidial release in G. pannorus.Although it is reported to be cellulolytic but not keratinolytic, G. pannorus is found on human skin, animals, birds, mushrooms, dung, roots, and frozen meat in addition to various organic soils. In fact, it readily adapts to growth at low temperatures.

Sign in / Sign up

Export Citation Format

Share Document