Journal ArticleDOI
Characterization of Nb Interface Segregation During Welding Thermal Cycle in Microalloyed Steel by Atom Probe Tomography
TLDR
In this paper, the binding energy of Nb atom and vacancy was predicted to be 0.45 eV, indicating that Nb segregation by welding thermal cycle is probably a result of the nonequilibrium mechanism.Abstract:
Coarse-grained, welding heat-affected zone microstructure was simulated in a Nb-bearing microalloyed steel. The granular bainite with a great number of martensite-austenite (M-A) constituents was the predominant phase. Using atom probe tomography (APT), the distributions of niobium at prior austenite grain boundary (PAGB), ferrite/martensite-austenite (M-A) constituent interface (FMAI), and ferrite/ferrite interface (FFI) were investigated. The binding energy of Nb atom and vacancy was predicted to be 0.45 eV, indicating that Nb segregation by welding thermal cycle is probably a result of the nonequilibrium mechanism. The maximum enrichment of Nb was found at FMAI with enrichment factor of 3.50. Intermediate enrichment of Nb was at PAGB with enrichment factor of 3.12. The interfacial excess of Nb solute element ГNb at PAGB determined by APT was 0.27 × 1019 atoms/m2. The segregation energy was calculated to be 22.91 kJ/mol. The minimum enrichment of Nb was at FFI with an enrichment factor of 1.80.read more
Citations
More filters
Journal ArticleDOI
Influence of cooling rate on the grain-refining effect of austenite deformation in a HSLA steel
H. Zhao,Eric J. Palmiere +1 more
TL;DR: In this paper, a low carbon Nb microalloyed steel was subjected to different austenite deformation conditions and was continuously cooled at a wide range of cooling rates (0.5~50°C/s).
Journal ArticleDOI
Quantitative analysis of Nb in solid solution in low carbon steels by atom probe tomography and inductively coupled plasma mass spectroscopy
Maina Portella Garcia,Hansheng Chen,Mehdi Eizadjou,Bryan Lim,Simon P. Ringer,Frank J. Barbaro +5 more
TL;DR: In this article, the authors compared inductively coupled plasma mass spectroscopy (ICP-MS) and atom probe tomography (APT) in determining the extent of Nb dissolution as a function of increasing temperature in two commercial American Petroleum Institute steel grades.
Journal ArticleDOI
Modelling stress relaxation after hot deformation: microstructure-property relationships in Nb-bearing steels
TL;DR: In this article , a vacancy-mediated dislocation climb approach is used to model the stress relaxation taking place after hot deformation by incorporating the simultaneous action of various physical phenomena, including dislocation recovery, recrystallization, and precipitation.
Journal ArticleDOI
Effect of Nb on inclusions and phase transformation in simulated high heat input coarse-grain HAZ of Nb/Ti low carbon microalloyed steel
TL;DR: In this article , the evolution and effect of Nb/Ti-containing complex inclusions were characterised and analyzed after being subjected to high heat input thermal simulation of 100 kJ/cm.
Journal ArticleDOI
Global and Local Corrosion of Welded Joints of High-Strength Low-Alloy Automotive Steel
Maina Portella Garcia,Juliana Sarango de Souza,Carol Glover,Phil Ansell,Geraint Williams,G. L. Mantovani,Ramachandran Vasant Kumar,Renato Altobelli Antunes +7 more
Abstract: Global and local corrosion techniques were used to study the corrosion behavior of weld joints of a high-strength low-alloy steel (LNE500) typically used in the automotive industry in Brazil. The welded joints were prepared by gas metal arc welding. Two welding transfer modes were used to obtain different heat inputs: pulsed (PUL) and cold metal transfer (CMT). Local and global corrosion analysis techniques presented complementary information. While the local in situ analysis (scanning vibrating electrode technique) revealed the weld metal (WM) as the region where corrosion started, conventional electrochemical techniques (potentiodynamic polarization [PP] and electrochemical impedance spectroscopy [EIS]) revealed a higher corrosion rate in the coarse-grained heat affected zone, which was preferentially corroded. A superior corrosion resistance of the WM obtained using CMT over the PUL transfer mode was revealed by EIS and PP. In addition, the results from CMT and PUL samples show that the austenite grain size affects the propagation of the corrosion process. The results are discussed based on microstructural and compositional aspects of the different regions that characterize the welded joints.
References
More filters
Book
Steels, Microstructure and Properties
TL;DR: In this article, the authors studied the effects of alloying elements in iron-carbon alloys and the formation of martensite, bainite reaction and acicular ferrite reaction.
Book
The Physical Metallurgy of Microalloyed Steels
TL;DR: In this article, the authors provide a substantial background to microalloyed steels with a wide selection of applications, some of which are very recent, and a well-illustrated practical guide.
Book
An introduction to metallurgy
TL;DR: The authors provide a broad overview of metallurgy from atomic theory, thermodynamics, reaction kinetics and crystal physics, to elasticity and plasticity, with a focus on elasticity.