bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser Brazing Phenomena of Heat-Resistant Alloys with Precious Brazing Filler Metals
Authors: Saida Kazuyoshi , Song Woo Hyun , Nishimoto Kazutoshi
Published: March 2009

The diode laser brazing of heat-resistant alloys with precious brazing filler metals has
been conducted using the tandem beam consisted of preheating beam and main brazing beam.
The 1mm thick plates of Inconel 600 and A286 alloys were butt-brazed with the 0.5mm diameter
Au-18%Ni, Ag-10%Pd and Ag-21%Cu-25%Pd filler metals using a brazing flux. The sound butt
joints which were free from brazing defects such as porosity and lack of penetration could be
obtained at the brazing clearances of 0.1-1.5mm. Fracture strength of braze joints using Au-Ni
and Ag-Cu-Pd filler metals was comparable to the base metal strength at any brazing clearance
between 0.1-1.5mm, whereas that using Ag-Pd filler metal increased with decreasing the brazing
clearance and attained about 70% of the base metal strength at brazing clearance of 0.1mm. The
computer simulations of the braze metal flowing and the base metal erosion suggested that the
preheating effect during the tandem beam brazing resulted in the superior brazability at the
narrow-gap as well as wide-gap brazing attributed to the improvement in the wetting, spreading,
infiltrativity and the erosion resistance of melted filler metal.
Grain Growth Behavior and Mechanical Properties of the Friction Stir Welded Zone of 7055 Al Alloy Followed by Post Weld Heat Treatment
Authors: Lee Won Bae , Lee Chang Yong , Yeon Yun Mo , Lee Jong Bong , Chae Shur Chang , Jung Seung Boo
Published: March 2009

The grain growth behavior and mechanical properties in the friction stir weld zone after
post weld heat treatment (PWHT) have been investigated. As PWHT temperature increased, a normal
grain growth of as-welded equaxied grains ceased and abnormally grown grains with elongated shape
coarsened. Huge elongated grains changed into smaller equaxied grains at 500°C. In case of lower
heat input condition, abnormal grain growth initiated faster due to smaller initial grain size. The weld
zone with bigger initial grains had advantages to maintain the thermal stability at high temperature.
The hardness near the weld zone was almost recovered to the 95% of the unaffected base metal at 500
°C and the weld zone under lower heat input condition resulted in the homogeneous recovery through
the whole weld zone.
Welding Phenomena in Hybrid Laser-Rotating Arc Welding Process
Authors: Chae Hyun Byung , Kim Cheol Hee , Kim Jeong Han , Rhee Se Hun
Published: March 2009

Hybrid laser-rotating arc welding (HLRAW) process was designed by combining the laser
beam welding (LBW) process with the rotating gas metal arc welding (RGMAW) process. In this
study, comparing with conventional HLAW, weld bead characteristics as a function of the various
process parameters were evaluated for HLRAW. Moreover, welding phenomena were analyzed by
high speed monitoring with laser illumination. The arc rotation enhances the weld pool motion,
therefore it reduces the undercut formation which is one of most critical weld defects in the
conventional laser-arc hybrid welding.
Modeling of Microstructural Gradients in TMCP Bars to Produce Value Added Products
Authors: Singh Balbir , Rai D.
Published: March 2009

Thermomechanical controlled processing of concrete reinforcement bars, comprising
quenching and autotempering, produces a microstructural gradient across the diameter - tempered
martensite near to the surface, bainite and/or degenerated pearlite in the intermediate layers and
pearlite-ferrite within the core. Since martensite is the strength controlling phase in steels, its
fractional thickness in TMCP bars have beeen correlated to tensile properties. The developed
empirical model, helped in revealing that upto a fractional rim of about 20%, volume fraction of
ferrite-pearlite predominantly influenced the YS, UTS and % elongation, whereas at higher
fractions, martensite found to control these properties.
Effect of Dislocations on Precipitation of Nb-C in α-Fe
Authors: Deschamps Alexis , Perrard Fabien , Bley Françoise , Donnadieu Patricia , Maugis Philippe
Published: March 2009

This paper presents a physically based precipitation model which aims at describing
precipitation kinetics when it occurs exclusively on dislocations. We present specific nucleation,
growth and coarsening equations, which are integrated in a set of differential equations. This model
is successfully applied to the case of precipitation of NbC in a ferritic steel, whose kinetics has been
determined by small-angle neutron scattering.
Atomic Bonding of Precipitate and Properties of Al-Cu-Mg Alloy
Authors: Gao Ying Jun , Hou Xian Hua , Huang Chuang Gao
Published: March 2009

Atomic bonding of the GPB zone and S′′ phase of Al-Cu-Mg alloys in early aging stage
are calculated using the empirical electron theory (EET) in Solid. The results show that not only the
covalence bond-net is very strong in GPB zone, but the whole covalence bond energy of S′′ phase
is also very large, all the primary bond-net framework of these precipitates can consolidate the
matrix of alloy. Phase transformation from GPB zone to S′′ phase is explained reasonably based on
atomic bonding and total binding capacity of Al and Cu atoms in these precipitates.
Effect of Cr on Strain Ageing Behaviour of Low Carbon Steel
Authors: Pereloma Elena V. , Bata V. , Scott R.I. , Smith R.M.
Published: March 2009

This work explores the effect of Cr addition on the kinetics of strain ageing process. The
strain ageing behaviour of low carbon steel with and without 0.7wt% Cr was investigated using
transmission electron microscopy (TEM), atom probe tomography (APT) and tensile tests. The
results have shown that Cr alloyed steel undergoes the same three stages of ageing as unalloyed low
carbon steel. However, the alloying with Cr reduces the rate of strain ageing by ~2 times in
comparison with non-alloyed low carbon steel. It especially delays the offset of stage III. This is
explained by the reduction of carbon content in ferrite due to the enrichment of cementite with Cr
leading to the reduction of its equilibrium solubility in ferrite.
A Physically Based Model for Bake-Hardening Steels and Dent Resistance
Authors: Uriarte Jean Louis , Perlade A. , Lemoine X. , Soler M. , Ballarin V. , Iung Thierry
Published: March 2009

Arcelor produces « Bake-Hardening » steels for automotive outer panels, which present
the advantages of a remarkable drawability combined with a significant hardening after stamping
and paint baking by the car maker. This hardening enables to increase the dent resistance of those
automotive parts.
In order to give easy design criterion and support the development for new “bake-hardening” steels,
a physically-based model for Bake-Hardening steels has been developed. It is suitable to predict:
-the physical phenomenon of strain ageing based on Cottrell atmospheres formation. A detailed
description of the strain ageing kinetics is given based on a generalized form of the Harper model
taking into account the diffusion of carbon atoms in the stress field of a dislocation, progressive
carbon depletion in the matrix and saturation of the available dislocation sites.
-the plastic instabilities propagation during tensile testing according to Piobert–Lüders phenomenon
using the finite element method. A local mechanical behaviour is introduced whose shape
schematically describes the local dislocation behaviour. The effect of the grain size on the velocity
of the Lüders’ band front is especially enlightened.
-the effect of ageing process on dent resistance. To do so, a physical extension of the former
approach to more complex loading paths is proposed.
Niobium in Microalloyed Structural and Engineering Steels
Authors: Klinkenberg Christian
Published: March 2009

The use of Niobium as a microalloying element is particularly beneficial in increasing
strength and toughness through its ability to control austenite grain size during reheating, and via
grain refinement and precipitation hardening after austenite transformation. Steels with lower
carbon contents can thus be utilised, further enhancing toughness and weldability.
Role of Manganese and Chromium on the Segregation Kinetics of Carbon and Nitrogen to the Dislocations in Ferritic Steels
Authors: Massardier-Jourdan Véronique , Colas David , Merlin Jacques
Published: March 2009

The thermoelectric power (or TEP) technique was used to determine the segregation
kinetics of the interstitial atoms (C or N) to the dislocations in various extra-mild steels submitted to
a heavy deformation by cold-rolling when substitutional atoms (Mn or Cr) are simultaneously in
solid solution. It was shown that the substitutional atoms (Mn or Cr) have almost no influence on
the segregation kinetics of carbon and on the activation energy associated with the segregation of
this element. In contrast, these elements tend to delay the segregation kinetics of nitrogen to the
dislocations all the more so as their content in solution is high. In the mean time, the activation
energy associated with the segregation of nitrogen is increased.
Modelling the Transformations Kinetics from Work-Hardened Austenite in a TRIP Steel
Authors: Fazeli F. , Militzer Matthias
Published: March 2009

Using physical concepts, an integrated transformation model to describe the kinetics of
ferrite and bainite formation from work-hardened austenite has been developed for a Mo-TRIP
steel. The ferrite sub-model assumes a mixed-mode kinetics under paraequilibrium condition and
accounts explicitly for the effect of alloying elements by considering their interaction with the
moving ferrite-austenite interface. To predict the onset of bainite formation, which corresponds to
the cessation of ferrite reaction along a given cooling path, a criterion based on a critical driving
pressure is formulated. Regarding the kinetics of the subsequent bainite reaction, the proposed
model adopts the Zener-Hillert diffusional approach. The proposed integrated model has been
employed to describe the continuous cooling transformation kinetics for a 0.19C-1.5Mn-1.6Si-
0.2Mo (wt%) TRIP steel that had previously been subjected to a systematic experimental study. The
predictive capabilities of the model and the challenges for further model improvements are
delineated.
Effects of Thermomechanical Processing on Microstructure and Mechanical Properties Multiphase Steels Exhibiting a TRIP Effect
Authors: Kliber Jiri , Plestilova Gabriela , Zacek Ondrej , Somani Mahesh Chandra
Published: March 2009

Effects of hot-rolling conditions on these steels are much less studied than their
importance for practice would suggest. It should be emphasized that bainite transformation is the
key reaction to enrich non-transformed austenite with carbon. This study was carried out in order to
gain understanding of the effect of thermomechanical hot rolling on final microstructure and
mechanical properties of C-Mn-Si TRIP steel. Fundamental of the transformation induced plasticity
effect – TRIP is the stabilization of substantial amount of retained austenite down to the ambient
temperature by thermomechanical processing and its subsequent transformation into strain induced
martensite as a consequence of applied plastic deformation. The special prepared stepped specimens
were rolled on laboratory tandem mill. The effects of finish rolling temperature, strain and
isothermal bainite transformation temperature on mechanical properties of mentioned TRIP steel
were evaluated (mechanical properties were examined with tension test). Major deformation, higher
finishing rolling temperature and higher temperature of bainite hold result in drop in strength.
Proportionately to the drop in strength, the ductility grows in the TRIP steel. Microstructures were
examined with X-ray diffraction (retained austenite). Image analysis software was used to process
SEM micrographs of structure (ferrite, bainite assessment). Plastometric testing was conducted on
GLEEBLE 3800 thermo-mechanical simulator. First stage of experiment yielded stress-strain
curves for various temperatures and strain rates. Gleeble 1500 was used for the remaining
plastometric simulation. Specimens were reheated to austenitization temperature of 1100°C and
soaked. Then they were cooled to the temperature of deformation and subsequently cooled at higher
rate down to the bainitic transformation temperature (400 – 550 °C). Specimens were held at the
bainitic transformation temperature and then air-cooled. Final microstructures were evaluated with
respect to transformation diagrams and optical microscopy findings. Higher bainite volume fraction
was found in the specimens cooled at higher cooling rate as compared with more slowly cooled
specimens.
Historical Aspects of Thermomechanical Processing for Steels
Authors: McQueen H.J.
Published: March 2009

Thermomechanical processing (TMP) involves both thermal and mechanical treatments
that define both product shape and microstructure/properties. Since the industrial revolution,
machines of augmented power, size and precision have given rise to TMP that challenged
explanation of the crystal mechanisms. In wrought iron, lamellar ferrite exhibited high transverse
crack resistance due to fine slag stringers that as flux facilitated welding of puddled bars in forging
of shafts or rolling of plates for bell-welding into pressure tight pipes; the substructure developed in
the iron as working continued below 900°C strengthened it. Patenting of high C steel wire led to an
optimum cold-drawn structure for outstanding strength and toughness. Hot forming technology,
combined with the refining potential for austenite decomposition gave rise to controlled rolling for
enhanced ferrite nucleation, ausforming to refine martensite and intercritical rolling to deform the
ferrite or to spheroidize the carbides. Cold rolling and annealing have been scheduled to impart
suitable strength, grain size, substructure and texture.
Mechanical Properties in Ultrahigh Strength Secondary Hardening Steels Bearing Co and Ni
Authors: Sim Ho Sup , Cho Ki Seop , Lee Kon Bae , Yang Hyung Ryul , Kwon Hoon
Published: March 2009

Applying the severe deformation, the mechanical properties related to secondary
hardening were investigated. The Mo-Cr-Co-Ni steels containing (5-13)wt% Co and (8-14)wt% Ni
were severely rolled at 850 °C, followed by direct quenching(DQ). DQ specimens were then
isothermally aged at 475°C. Ni additions promoted aging kinetics, accompanied by a little
enhancement in hardness. In contrast, Co additions enhanced the peak hardness, but did not induce
a remarkable aging acceleration. In the 13Co addition group, an actual secondary hardening, that is,
the peak hardness is higher than the as-quenched hardness. Variation in peak hardness(Rc) in alloys
is summarized as follows; 14Ni-13Co(57.2) ≒ 11Ni-13Co(57.1) > 8Ni-13Co(56.5) > 11Ni-
9Co(56.2) > 8Ni-9Co(54.4) > 11Ni-5Co(53.4).
Original Position Statistic Distribution Analysis (OPA)-Novel Statistic Characterization Method of Different Chemical Compositions and its States of the Materials
Authors: Wang Hai Zhou
Published: March 2009

Original position statistic distribution analysis (OPA) is a new analytical method to
determine the quantitative distribution of different chemical compositions and their states of the
materials. A novel quantitative metal original position analyzer has been invented by combining
the technology of Single Discharge Analysis (SDA) and continuous scanning excitement spark
spectrum without pre-excitement. This analytical method can be used to analyze the original
position statistic distribution of metals. In this study, the following examples were provided:
Quantitative statistic distribution of contents of various elements on the deferent locations in
materials; Quantitative statistic distribution of weight in deferent contents of the various elements;
Accurate calculation of the segregation of various elements in materials; Quantitative description of
the homogeneity of materials; Quantitative statistic distribution of weight in different contents of
the elements in total excitement signals of materials; Quantitative description of the porosity in
materials; Quantitative statistic distribution of inclusion contents on different locations in materials
and distribution of inclusion sizes in materials. The concept of original position statistic distribution
analysis along with the widely utilization of the metal original position analyzer will provide
researchers and scientists a new method to study the internal characteristics and predict the
properties of the materials
Retained Austenite - Residual Stress - Distortion Relationships in Carburized SAE 6820 Steel
Authors: Northwood Derek O. , He Lily , Boyle Erin , Bowers Randy J.
Published: March 2009

SAE 8620 steel is typically used in the carburized condition for powertrain applications
in the automotive industry, e.g. gears, roller bearings, camshafts. Such steels always contain
retained austenite to varying degrees in the as-hardened and also in the tempered microstructures.
As well as retained austenite, heat treatment can produce residual stresses, which lead to distortion
(size and shape). The intent of this study was to investigate the effect of heat treatment parameters
on the amount of retained austenite, residual stress and distortion in carburized SAE 8620 steel.
A specially designed specimen, the Navy C-ring, was used for this study. The steel was first
normalized prior to machining the Navy C-ring specimens. The specimens were then heat treated
by carburizing at 927°C or 954°C (1700°F or 1750°F) at four levels of carbon potential (0.9, 1.0,
1.1, 1.2) followed by oil quenching and tempering at either 149°C or 177°C (300°F or 350°F). The
distortion of the C-ring was evaluated by dimensional measurements of the inner diameter, outer
diameter, gap width and thickness for size distortion, as well as flatness, cylindricity and roundness
for shape distortion. X-ray diffraction (XRD) techniques were used to determine the residual stress
and the amount of retained austenite. The amount of retained austenite was also measured by
optical metallography. The amount of retained austenite and the residual stress increased with
increasing carburizing temperature and carbon potential and decreased upon tempering. There was
not a significant further reduction in the amount of retained austenite and residual stress when the
tempering temperature was increased from 149°C to 177°C. Distortion was influenced by both the
amount of retained austenite and the magnitude of the residual stress. With increasing retained
austenite/residual stress, the distortion became more serious. Based on the distortion data for 3
parameters (OD, gap width and flatness) for the quenched and tempered specimens, the amount of
retained austenite for minimum distortion was approximately 25%.
Comparison between Charpy Transition Temperature TCVN and Reference Temperature T° for 10Ni3CrMoV Steel
Authors: Gao Yi Fei , Shen Jun Chang , Wu Bo Qun
Published: March 2009

Charpy transition temperature TCVN and reference temperature To for 10Ni3CrMoV
steel were determined using two different experimental techniques such as Charpy V-notch impact
test technique and reference temperature To test technique. It was found that two methods
provided different test results. The median master curve with upper and lower tolerance bounds
was got from the test. The upper tolerance bound is often used for material design and application.
At the same time the TCVN and To results were discussed for two kinds of heat treatment which are
QT(Quenching and Temper) and QLT(Quenching, anneal and temper). JC (med ) K values
calculated were 101 and 105MPam1/2 for the QT and QLT steels, respectively. These indicated that
the QLT steels have the higher JC (med ) K , the lower reference temperature and lower energy (or
fracture appearance) transition temperature(ETT50 or FATT50) than the QT steels. This was mainly
related with the different microstructures of two kinds of heat treatment.
Optimized Thermomechanical Treatment for Strong and Ductile Martensitic Steels
Authors: Barani Araz Ardehali , Ponge Dirk
Published: March 2009

In this study the effect of thermomechanical treatment on the microstructure of austenite
and martensite and the mechanical properties of a medium carbon silicon chromium spring steel with
different levels of impurities is investigated. Results are presented for conventional heat treatment and
for thermomechanical treatment (TMT). Compared to conventionally heat treated samples austenite
deformation improves strength and ductility. Thermomechanically treated samples are not prone to
embrittlement by phosphorous. TMT influences the shape and distribution of carbides within the
matrix and at prior austenite grain boundaries. It is shown that utilization of TMT is beneficial for
increasing the ultimate tensile strength to levels above 2200 MPa and at the same time maintaining
the ductility obtained at strength levels of 1500 MPa by conventional heat treatment. The endurance
limit is increased and embrittlement does not occur.
Graphitization Behavior of a Spray Formed Ultra High Carbon Steel during Hot Rolling
Authors: Shi Hai Sheng , Luo Guang Min , Fan Jun Fei , Lin Yi Jian , Zhang Jing Guo
Published: March 2009

The effect of hot rolling parameters on graphitization of a spray formed
ultra high carbon steels(UHCSs) was described. The number of graphite stringers and
graphite area fractions increased with the increase of rolling reduction. Graphite
stringers nucleated at small pores and grew by carbon diffusion from adjacent
austenite during hot rolling. Alloy contents, pores and hot deformation atγ+Fe3C
phase range are the key factors for graphitization.The graphite stringers of UHCSs
have little effect on tensile strength, but reduce the ductility at room temperature.
Simulation of the Process of Hot Rolling of Seamless Tubes
Authors: Carvalho Ricardo Nolasco , Ferreira Marcelo A.C. , Santos Dagoberto Brandão , Barbosa Ronaldo
Published: March 2009

Seamless tubes are manufactured, as it is well known, via continuous mandrel rolling
process. A billet is first pierced, then the hollow is reduced and rolled with mandrel at temperatures
higher than 1000oC. After mandrel extraction, the hollow can either cool down to room temperature
or be directly charged in an intermediate furnace for re-austenitization. Finally, the tube is finished
in a stretch-reducing mill to several gauges. The thermomechanical process is complex allowing
little flexibility along the line. The aims of this paper are a) to describe the industry schedule in
terms of simple process variables and b) to simulate this process via numerical and physical models.
The latter uses torsion testing as experimental technique. It is shown that good agreement is
obtained between industry results and predictions from the numerical model. Torsion experiments
have produced somewhat larger predictions for ferrite grains sizes, however. This is mostly
attributed to the necessary simplifications made to the mechanical testing experiments due to
restrictions in maximum strain rates and shortest dwell times achievable with thermomechanical
simulators.
A Phase Transformation Model for the Austenitisation of Martensite in Dual-Phase Steel
Authors: Thiessen Richard G. , Sietsma Jilt , Richardson I.M.
Published: March 2009

This work presents a unique approach for the modelling of the austenitisation of martensite in dual-phase
steels within the phase-field method. Driving forces for nucleation and growth are derived from thermodynamic
databases. Routines for nucleation are based on a discretisation of the classical nucleation theory. Validation is given via
dilatometric experiments.
An EBSD Study of Orientation Relationships during Phase Transformations in Ultra High Performance Steels
Authors: Godet Stéphane , He You Liang , Jonas John J. , Jacques Pascal J.
Published: March 2009

The orientation relationships that apply to phase transformations in high-performance
TRIP and TWIP steels were characterised by orientation imaging and EBSD techniques. The results
are presented in the fundamental zones of Rodrigues-Frank space that correspond to the specific
phase transformation under consideration (cubic to cubic or cubic to hexagonal). The use of
Rodrigues-Frank space enables straightforward comparison to be made with orientation
relationships proposed in the literature. The observations indicate that the active slip systems in the
parent phase play important roles in variant selection.
Austenite Formation in C35 and C45 Alloys
Authors: Savran V.I. , van Leeuwen Y. , Hanlon Dave N. , Sietsma Jilt
Published: March 2009

The first step in the heat-treatment processes for a vast majority of commercial steels is
austenitization. There is much less research put in this field comparing to the cooling
transformation, but the interest is continuously increasing especially in view of the development of
TRIP and Dual-phase steels.
The microstructural evolution during continuous heating experiments has been studied for a
series of C-Mn steels with carbon contents in the range 0.35-0.45 wt. % using optical and
scanning electron (SEM) microscopy. It is shown that the formation of the austenitic phase is
possible in pearlitic as well as in ferritic regions, although in the former it proceeds at a much
faster rate due to the shorter diffusion distances. Thus a considerable overlap in time of the ferriteto-
austenite and the pearlite-to-austenite transformations is likely to occur.
Another observation that was made during the experiments is that depending on the heating
rate, the pearlite-to-austenite transformation can proceed in either one or two steps. At low
heating rates (0.05 °C/s) ferrite and cementite plates transform simultaneously. At higher heating
rates (20 °C/s) it is a two-step process: first ferrite transforms to austenite within pearlite grains
and then the dissolution of the cementite lamellae takes place.
Cold Workability and Magnetic Properties of 6% Si Steel
Authors: Shin Je Sik , Kim Bo Hyun , Lee Sang Mok , Moon B.M.
Published: March 2009

In order to develop an economical production method of high Si steel sheet, 6%Si (by weight
percent, unless specified otherwise) steel was prepared by a combined process of conventional casting and
hot- and cold-rolling. Tension and nano-hardness tests and TEM analysis were carried out to examine the
effects of ordered phases, Si-content, and testing temperature on cold workability. By optimizing the
successive processes of casting, hot-rolling, heat treatment, and cold-rolling, 0.5 mm thick 6%Si steel sheet
was successfully produced without crack formation. As Si content increased from 3% to 6%, core loss
(W10/50) of the 0.5 mm thick Si steel sheet decreased from 1.36 W/kg to 0.89 W/kg.
Interactions between Recrystallisation and Phase Transformations during Annealing of Cold Rolled Nb-Added TRIP-Aided Steels
Authors: Andrade-Carozzo V. , Jacques Pascal J.
Published: March 2009

Fe and Fe-C based alloys present the exceptional feature that the processing route can be
adapted to lead to various phases that present antagonist mechanical properties ranging from soft
ferrite to high strength martensite. Among the different deformation mechanisms that can be
exhibited by these phases, the TRIP effect brings about large enhancements of the work-hardening
rate. The current TRIP-assisted multiphase steels present a ferrite-based matrix with a distribution
of islands of bainite and retained austenite obtained at the end of specific thermal or
thermomechanical treatments.
The present study aims at characterising the interactions occurring between ferrite recrystallisation
and austenite formation during the intercritical annealing of cold rolled Nb-added TRIP-aided steels.
It is shown that the addition of niobium retards the ferrite recrystallisation during heating. As a
consequence, ferrite may not be completely recrystallised before the nucleation and growth of the
austenite grains. Strong interactions between these phenomena can then be observed, i.e. a strong
hindering of the ferrite recrystallisation due to the austenite formation. Furthermore, the heating rate
from room temperature to the intercritical temperature range influences the thermodynamic
conditions prevailing at the ferrite / austenite interface and dictates the phase proportions.
Influence of Magnetic Field on the Mechanical Properties of Austempered Ductile Iron (ADI)
Authors: Putatunda Susil K.
Published: March 2009

A novel concept of two-step austempering in a magnetic field has been conceived by this investigator. This twostep
process involves first quenching the alloy to a lower temperature after austenitizing and then immediately
rising the temperature of the quenching media to a higher temperature and the whole austempering process is
carried out in the presence of a high magnetic field. In this investigation, Austempered Ductile Iron (ADI) was
processed by this novel two-step austempering process in a high magnetic field of 20 Tesla. The microstructure
and the mechanical properties of the ADI processed in a magnetic field has been characterized and compared
with ADI processed by conventional process.
The results of this investigation indicate significant improvement in the mechanical properties of ADI
when Austempered in a high magnetic field. Both yield and tensile strengths were higher in the samples
processed in the presence of a magnetic field. Very fine grain ferrite and austenite was obtained in the
microstructure. The ferrite content was also significantly higher.
Gas Quenching with Controllable Heat Extraction
Authors: Liščić Božidar
Published: March 2009

High pressure gas quenching became a modern way of quenching finally machined engineering
components,having many advantages compared to quenching in liquid quenchants.The main
shortcoming of this technology is the problem of achieving adequate hardness in the core of bigger
workpieces,because of inadequate quenching intensity.Due to the possibility to change gas pressure
and its flow velocity,combined with transient spraying of liquid nitrogen during the quenching
process ,the intensity of cooling can be instantly increased during selected time intervals.In this way
the heat extraction dynamics can be automatically controlled,and a predetermined path of the heat
transfer coefficient can be followed.Preliminary experiments show that using the controllable heat
extraction(CHE) technology, the mentioned shortcoming can be eliminated.Theoretical background
of the CHE technology is described,with particular attention to the depth of hardening,and to
residual stresses.Possibilities and prerequisite conditions for application of the CHE technology in
vacuum furnaces,and for automatic heat extraction control,are discussed.
Morphological Evolutions in Steels during Continuous Rapid Heating
Authors: Kaluba Wlodzimierz , Kaluba T. , Zielinska-Lipiec Anna
Published: March 2009

The influence of high energy density sources on morphological changes in steels was
studied by a physical simulation. Strips of carbon steels were subjected to heat cycles including
continuous rapid heating to temperatures between 400 and 1200°C and immediate water quenching.
The heat cycles were carried out by passing a high intensity electrical current through trapezoidal
specimens in a special device allowing to obtain heating rates up to 10000°/s with an excellent
temperature control. Real-time temperature recordings were drawn so as to define some
characteristic temperatures of continuous austenitization. The evolution of the morphology, initially
composed of ferrite and martensite, was examined by means of light and electron (SEM and TEM)
microscopy using standard techniques. The results of the examination were related to microhardness
measurements. Three distinct stages of the morphological evolution were finally analyzed:
- T > AC1 - Beginning of austenite formation in zones of as-tempered martensite, mostly at former
austenite grain boundaries.
- AC1 << T < AC3 - Development of irregular lath-shaped interface between the growing
(austenite) and shrinking (ferrite) phases.
- T > AC3 - Final massive transformation of supersaturated ferrite areas.
Weldability of Ultra-Fine Grained Atmospheric Corrosion Resistant Steel
Authors: Peng Yun , Xiao Hong Jun , He Chang Hong , Tian Zhi Ling , Ma Cheng Yong , Zhang Xiao Mu
Published: March 2009

Thermal simulation and arc welding were carried out to test the weldability
of atmospheric corrosion resistant steel 07MnCuPTiNb. In thermal simulation
experiment, welding thermal cycles with different peak temperature and different
cooling rate were adopted and the microstructure and impact toughness were analyzed.
In arc welding experiment, different heat input was used and the microstructure,
impact toughness, hardness distribution, tensile strength and bending ductility of
welded joints were examined. When small heat input is used for welding, the impact
toughness of HAZ remains to be good. The broken position of tensile test specimen is
located in base metal zone. The joint also has good ductility.
Substructures and Fatigue Crack Growth in HIPing and Semi-Liquid Die Casting A356 Alloys
Authors: Han Sang Won , Lee Hyuck Mo
Published: March 2009

Permanent mold and semi-liquid die A356 cast alloys were used to examine the roles
of microstructures and aging conditions on fatigue crack growth. HIP treatment to the A356 alloy
generates substructure like dendritic arm boundaries as well as reduction of pores, which improves
fracture elongation and fatigue fracture toughness. The similar substructure occur at primary α-Al
and inter Si particles of semi-liquid die cast, too. Fracture elongation of HIPed permanent mold cast
is comparable to that semi-liquid die cast, the fatigue crack growth is faster than in semi-liquid die
cast. Plastic hardening occurs around fatigue crack flank, which decreases fatigue crack growth rate,
and such effect appears highly in under aged alloy.
Equal Channel Angular Pressing in a Pearlitic Structured Steel
Authors: Huang Jun Xia , Wang Jing Tao
Published: March 2009

Equal Channel Angular Pressing (ECAP) in a fully pearlitic structured steel
65Mn was successfully carried out at 923 K via route C in this study. The severe shear
deformation of ECAP was accommodated by periodical bending, periodical shearing
and shearing fracture etc in the pearlitic lamellae. The cementite in the pearlite has
higher plastic deformation capability. Excessive imperfections may be introduced into
the cementite, which supplies additional energy driving for the following
spheroidization of cementite in subsequent processing. After five ECAP passes, the
fully pearlitic lamellae evolved into a microstructure of ultrafine-grained ferrite
matrix uniformly dispersed with finer cementite particles. The ferrite matrix is
homogeneous with an average grain size of ~0.3 micrometers. Two possible
mechanism for the spheroidization of cementite were proposed：heterogeneous
growth of the fractured cementite fragments, and the precipitation of new fine
spherical cementite particles through nucleation and growth.
Ultrafine Grained Steels due to Super Short Interval Multi-Pass Rolling in Stable Austenite Region
Authors: Miyata Kaori , Wakita Masayuki , Fukushima S. , Eto M. , Sasaki T. , Tomida Toshiro
Published: March 2009

Ultrafine-grained steel sheets with the chemical composition of 0.15%C-0.74%Mn-
0.01%Si have been prepared using a laboratory rolling mill by Super Short Interval Multi-pass
Rolling (SSMR) process, in which the inter-pass time is extremely shortened to enhance the
cumulative strain. The SSMR process with a finish rolling around Ae3 leads to ultrafine equiaxed
ferrite structure with 1μm in average grain size. In order to clarify the grain refinement mechanism
in the SSMR process, the deformation substructure in deformed austenite was simulated using
70%Ni-30%Fe, which was a fcc alloy with equivalent stacking fault energy to C-Mn steels. TEM
observations have shown that the dislocation substructure in the Ni-Fe alloy hot-rolled by SSMR
process mainly consists of dislocation cells, of which size are refined to less than 1μm with
shortening inter-pass time. It is concluded that the SSMR process can accumulate the deformation
strain in austenite enough to densely nucleate ferrite inside austenite grains.
Effect of Ultra-Fast Cooling after Rolling in Stable Austenite Region on Grain Refinement of C-Mn Steel
Authors: Tomida Toshiro , Imai N. , Yoshida Mitsuru , Fukushima S.
Published: March 2009

Ferrite grain refinement by hot rolling mostly above Ae3 being followed by an ultra-fast
cooling has been investigated. An emphasis has been paid on the interval, Δt, between the finish of
rolling and the start of water spray cooling of which cooling rate is more than 1000 °C·s-1. When Δt
was nearly equal to zero, ultra-fine ferrite of about 1 or 2 μm in grain diameter was obtained for 1.2 to
1.3 mm thick 0.1%C-1%Mn steel sheets near sheet surfaces or in thickness center regions
respectively, although the grain size at Δt of 0.5 s was about 3 μm in both regions. The ferrite grains
were almost equiaxed and surrounded by high angle boundaries. This grain refinement is likely to be
caused by an increased number of nucleation sites for the transformation from austenite to ferrite due
to the ultra-fast cooling. Such a grain refinement mechanism is discussed in terms of prior-austenite
structures deduced by the misorientation distribution function analysis.
Steels with Ferrite-Bainite Microstructure with Improved Weldability and Cold Resistance for Main Pipelines
Authors: Nastich S.Y. , Morozov Y.D. , Efron L.I. , Matrosov M.Y.
Published: March 2009

The required complex of properties of modern pipe steels, including improved
weldability and cold resistance, can be achieved due to formation of fine-grained ferrite-bainite
microstructure of steel. Effect of various designs of additional alloying of steel on phase
transformations with use of deformation CCT diagrams is investigated. Key parameters of TMCPtechnology,
necessary for obtaining the best complex of properties of plate and strip products are
determined. Results of industrial trials in production of steel with ferrite-bainite microstructure of
Russian steel manufacturers are presented.
Development of Modern Heavy Plate Steels for Pipelines
Authors: Matrosov Yu I. , Bagmet O.A. , Nosochenko A.O.
Published: March 2009

Azovstal Iron & Steel Works (Ukraine) together with I.P. Bardin Central Research
Institute (Russia) carry out research intended for development and realization of new HSLA-steels
for large diameter gas pipelines of strength categories X60 through X80. A concept that has been
recently adopted for creation of new pipeline steels calls for lower carbon content, bigger role of Nb
microalloying, economical alloying with elements improving austenite resistance to perlite
transformation, thermomechanical controlled rolling with strain finishing in two-phase γ+α-region.
This paper describes the research results obtained for commercial lots of rolled steel plates of
various alloying systems intended for X65 and X80 longitudinally electric welded pipes.
Grain Scale Assessment of Variant Selection in a Thermomechanically Processed TRIP Steel
Authors: He You Liang , Godet Stéphane , Jonas John J.
Published: March 2009

Orientations of both the α and γ phases in a multi-phase commercial steel were measured
by means of electron backscatter diffraction (EBSD) techniques. Using the average orientation of
each austenite grain as the reference frame, the orientation relationships between the two lattices
were compared with the common orientation relationships (i.e. the Kurdjumov-Sachs and
Nishiyama-Wassermann) in Rodrigues-Frank space. The occurrence of variant selection in
individual austenite grains was examined using a recent dislocation-based model. This model
considers the role of the slip systems that were active during prior deformation, as well as those of
in-plane reactions, cross-slip and the partial dislocations that are linked to specific variants. It also
unites the competing K-S and N-W relationships through the dissociation of perfect dislocations.
Reasonably good agreement was observed between the predictions and the observations. Possible
explanations for some of the discrepancies are also presented.
Effect of Carbon on Work Hardening Behavior of 18%Ni Martensitic Steel
Authors: Nakashima Koichi , Fujimura Y. , Tsuchiyama Toshihiro , Takaki Setsuo
Published: March 2009

The behavior of work hardening by cold rolling and tensile deformation was investigated
in an ultralow carbon and carbon bearing martensitic steels, and then the effect of carbon on the
work hardening behavior was discussed in terms of the change in dislocation density and the
microstructure development during deformation. In the ultralow carbon 18%Ni steel (20ppmC), the
hardness is almost constant irrespective of the reduction ratio. On the other hand, the carbon bearing
18%Ni steel (890ppmC) exhibits marked work hardening. The dislocation density of these
specimens was confirmed to be never increased by cold rolling. It was also found that 10% cold
rolling gives no significant influence on the morphology of martensite packet and block structure.
TEM images of the 10% cold-rolled steels revealed that the martensite laths in the ultralow carbon
steel are partially vanished, while those in the carbon bearing steel are stably remained. These
results indicate that the solute carbon retards the movement of dislocations, which results in the
high work hardening rate through the formation of fine dislocation substructure within laths.
Modeling of Microstructure Evolution of Athermal Transformation of Lath Martensite
Authors: Sherman Don H. , Yang Bing J. , Catalina Adrian V. , Hattiangadi Ashwin A. , Zhao Patrick , Chuzhoy Leo , Johnson Michael L.
Published: March 2009

Martensitic microstructures in steels provide the strength and toughness required for the
dynamic loads experienced by construction and mining machines. Such microstructures are
produced with appropriate heat treatments. A physics based model has been developed to represent
the microstructure evolution during the martensitic transformation. This modeling has been used to
understand the role of as-quenched microstructure on subsequent processing. This paper describes
modeling the martensitic transformation in steels under different cooling rates. The model
described in this paper has been validated with a medium carbon, low alloy steel.
Microstructural Features of 'Quenching and Partitioning': A New Martensitic Steel Heat Treatment
Authors: Edmonds D.V. , He K. , Miller Michael K. , Rizzo F.C. , Clarke A. , Matlock David K. , Speer John G.
Published: March 2009

The microstructure following a new martensite heat treatment has been examined,
principally by high-resolution microanalytical transmission electron microscopy and by atom probe
tomography. The new process involves quenching to a temperature between the martensite-start (Ms)
and martensite-finish (Mf) temperatures, followed by ageing either at or above, the initial quench
temperature, whereupon carbon can partition from the supersaturated martensite phase to the
untransformed austenite phase. Thus the treatment has been termed ‘Quenching and Partitioning’
(Q&P). The carbon must be protected from competing reactions, primarily carbide precipitation,
during the first quench and partitioning steps, thus enabling the untransformed austenite to be
enriched in carbon and largely stabilised against further decomposition to martensite upon final
quenching to room temperature. This microstructural objective is almost directly opposed to
conventional quenching and tempering of martensite, which seeks to eliminate retained austenite
and where carbon supersaturation is relieved by carbide precipitation. This study focuses upon a
steel composition representative of a TRIP-assisted sheet steel. The Q&P microstructure is
characterised, paying particular attention to the prospect for controlling or suppressing carbide
precipitation by alloying, through examination of the carbide precipitation that occurs.
Analysis of Spherical Carbides Formed in Chromium Added Hypereutectoid Bearing Steels
Authors: Yamamoto Atsushi , Inoue Katsuhiko , Tsubakino Harushige
Published: March 2009

Microstructures in a bearing steel, JIS SUJ2, have been observed and analyzed in
detail by means of transmission electron microscope and synchrotron radiation diffraction in
SPring-8. Spherodized carbides in the steel are generally recognized as spherical cementite
particles, but some of them have been clearly shown to be M23C6 type of carbide in this study.
The shapes and sizes of these two types of carbides are similar to each other. On the martensitic
matrix of the steel, it is believed to be stable at relatively low temperature, but it is also shown to
be decomposed to form cementite by prolonged aging at 383 K, which provides a reason for
decrease in hardness in standard hardness blocks, previously reported by the authors.
Structure and Properties of AlMg3 Alloy with Sc and Zr
Authors: Očenášek Vladivoj , Smola Bohumil , Stulíková Ivana , Pelcová J.
Published: March 2009

The present contribution deals with the effect of thermal and mechanical treatment on
structure, mechanical and physical properties of as cast, cold and hot worked AlMg3 type alloy
produced by conventional casting, as well as by powder metallurgy. The properties of the AlMg3
alloys with additions of Sc and Zr in the weight concentration ranges 0.14 – 0.29% and 0.05 –
0.12% respectively were studied and compared with those of the alloys without Sc and Zr additions.
The anti-recrystallization effect, phase development and mechanical properties investigated in the
course of isothermal as well as isochronal annealing were studied by using optical and transmission
electron microscopy, electrical resistometry and hardness measurements. The parameters of
technological procedure of optimum age hardening by the Al3(ScxZr1-x) phase are presented. This
optimum can not be reached if the as cast alloy is exposed to temperatures higher than 350°C. Even
the small additions of Sc such as 0.15 wt. % ensure the anti-recrystallization effect of Al3(ScxZr1-x)
phase.
Prediction of Properties in Type 347 Austenitic Stainless Steel after Long-Term Service at High Temperatures
Authors: Nilsson Jan Olof
Published: March 2009

The evolution of microstructure during production and elevated temperature service of
type 347 austenitic stainless steel in the temperature range 700-800°C was modelled using
commercial software packages such as Thermo-Calc and DICTRA and characterized using
various microscopical techniques. The growth and coarsening of niobium carbonitrides and σ-
phase were modelled as well as nitrogen uptake. Good agreement between predictions and
microstructural observations was found.
The Strain-Independence of Interpass Softening during the Hot Compression of 304 H Stainless Steel
Authors: Najafizadeh Abbas , Jonas John J.
Published: March 2009

The kinetics of interpass softening and the strain (ε*) at which they become
strain-independent were determined by means of double-hit hot compression tests. For this
purpose, interrupted compression tests were conducted at strain rates of 0.01 and 0.1 s-1 to
initial strains ranging from that corresponding to the initiation of DRX (εc) to the onset of
steady state flow (εs.). Test temperatures between 1000 and 1100 °C (inclusive) were
employed. Interpass times were varied from 0.3 to 1000 seconds. The fractional softening
was determined using the 0.2% offset method.
It is clear from the results that there is a transition strain (ε*) that separates the straindependent
range of post-dynamic softening from the strain-independent range. The value of
ε* obtained in this work was ε* = 4/3 εp. It was also found that the strain hardening rate was
identical at all the critical strains (ε*) and took the value -22 MPa.