Effect of Ca on Grain Size and Toughness in CGHAZ of C-Mn Steel

2011 ◽  
Vol 291-294 ◽  
pp. 886-889
Author(s):  
Kun Ning Jia
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Second Phase ◽  
Pinning Force ◽  
Second Phase Particles ◽  
Impact Experiment ◽  
Strong Pinning ◽  
Mn Steel

Through adding enough calcium to C-Mn steel, the second phase particles of CaO can be found in C-Mn steel. The microstructure, the grain size and the toughness of CGHAZ in micro-calcium steel and no micro-calcium steel were studied by TEM, SEM and series impact experiment. The research shows that: the second phase particles CaO in micro-calcium steel have strong pinning force to grain boundary of CGHAZ; the second phase particles can retard grain growth in the course of welding in micro-calcium steel, fining grain at CGHAZ and improving the toughness of CGHAZ in micro-calcium steel.

On the theory of the effect of precipitate particles on grain growth in metals

1966 ◽  
Vol 294 (1438) ◽  
pp. 298-309 ◽  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Energy ◽  
Second Phase ◽  
Pinning Force ◽  
Essential Difference ◽  
The Matrix ◽  
Critical Particle Size

A theoretical model of the energy changes accompanying grain boundary movement has been developed. It has been shown that small boundary movements will reduce the energy of a polycrystalline metal only when there is a heterogeneous grain size. The pinning force exerted by precipitate particles of a second phase on the grain boundary has also been considered. The release of grain boundary energy which accompanies grain growth has been considered as a source of energy for the unpinning process. The theory predicts a critical particle size which is dependent on the volume fraction of second phase, the matrix grain size, and the degree of heterogeneity of the matrix. Coalescence of the precipitate to a size in excess of the critical radius will permit grain growth to occur. Theoretical predictions of the critical particle size are in good agreement with values determined experimentally. The essential difference between grain growth and secondary recrystallization is indicated by the theory.

Phase Field Simulation of Grain Growth with Particle Pinning

2016 ◽  
Vol 724 ◽  
pp. 8-11
Author(s):  
Chun Yu Teng ◽  
Yun Fu ◽  
Zhan Yong Ren ◽  
Yong Hong Li ◽  
Yun Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Phase Field ◽  
Particle Number ◽  
Boundary Energy ◽  
Service Condition ◽  
Second Phase ◽  
Pinning Effect

The properties of alloys depend on its microstructure, such as the size of grains. In general, the balanced mechanical properties of alloys can be obtained with small grain size. While the grain size of alloys may increases under heat treatment, thermal mechanical processing and service condition of high temperature, i.e., the grain growth is inevitable. The effort of most research is to control the rate of grain growth and avoid abnormal grain growth. For example, pinning the grain boundary and reduce its mobility with the second phase particles in order to prevent grain growth. Therefore, the properties of the alloys will not decreases dramatically and the structure retains a high degree of integrity. The details of grain growth with particle pinning were investigated by phase field simulations in the present paper. It is found that, with the same size of pinning particles, the pinning effect increases with the increases of the pinning particle number. With the same pinning particle number, the pinning effect increases with the increases of pinning particle size. Under the same total volume of pinning particles while different particle size and number, the pinning effect is complicated and it will be discussed in details. The pinning effect decreases with the increases of grain boundary energy. These findings could shed light on the understanding of the grain growth kinetics with particle pinning.

Abnormal Grain Growth and Texture Development

2005 ◽  
Vol 495-497 ◽  
pp. 1171-1176 ◽  
Author(s):  
Anthony D. Rollett
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Abnormal Grain Growth ◽  
Polycrystalline Materials ◽  
Second Phase ◽  
Goss Texture ◽  
Electrical Steels ◽  
Second Phase Particles ◽  
Euler Space ◽  
Boundary Properties

A theory for abnormal grain growth (AGG) in polycrystalline materials is revisited and extended in order to predict AGG in textured polycrystals. The motivation for the work is to improve our understanding of the origins of the Goss texture component, {110}<001>, during annealing of Fe-Si sheet. Since the AGG phenomenon in grain-oriented electrical steels is known to be dependent on the presence of a dispersion of fine second phase particles, the grain boundary properties are treated as representative of the homogenized behavior of the material, and not necessarily the properties that would be measured directly. The predictions of AGG are presented in the form of maps in Euler space, showing which texture components are most likely to grow abnormally. For different models of grain boundary properties applied to a theoretically derived texture, different sets of texture components are predicted to grow; neither model, however, predicts growth of the Goss component.

THERMAL STABILITY OF NANOCRYSTALLINE COPPER FILMS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3830-3835 ◽  
Author(s):  
PENG CAO ◽  
DELIANG ZHANG
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Phase Particle ◽  
Second Phase ◽  
Pinning Force ◽  
Nanocrystalline Copper ◽  
Grain Growth Kinetics ◽  
Kinetics Of

The grain growth kinetics of nanocrystalline copper thin film samples was investigated. The grain size of nanocrystalline copper samples was determined from the broadening of X-ray spectra. It was found that the grain size increased linearly with isothermal annealing time within the first 10 minutes, beyond which power-law growth kinetics is applied. The activation energy for grain growth was determined by constructing an Arrhenius plot, which shows an activation energy of about 21 – 30 kJ/mol. The low activation energy is attributed to the second phase particle drag and the porosity drag, which act as the pinning force for grain growth in nanocrystalline copper.

Influence of the Second Phase Particle’s Size Distribution on Grain Growth Based on Computer Simulation

2011 ◽  
Vol 239-242 ◽  
pp. 930-933
Author(s):  
Xiao Fei Ma
Keyword(s):  
Grain Boundary ◽  
Size Distribution ◽  
Grain Growth ◽  
Theoretical Models ◽  
Second Phase ◽  
Pinning Effect ◽  
Second Phase Particles ◽  
Average Grain Size ◽  
Relationship Of ◽  
The Relationship

Based on cellular automata, a model of simulating grain growth is established to study the effects of the second phase particle’s size distribution on grain growth. The simulation results show that the second phase particles in the matix pin the grain boundary and then inhibit the grain growth. Different size distributions of the second phase particles have different pinning effect on the grain boundary, and the relationship of average grain size for the material with the second phase particles is RLognormal＞RUniform＞RNormal. The correlative laws obtained from the simulation is in accordance with the theoretical models.

Effect of Particle Size on the Zener Limit: A Monte Carlo Simulation Approach

2012 ◽  
Vol 560-561 ◽  
pp. 152-155 ◽  
Author(s):  
Kalale Raghavendra Rao Phaneesh ◽  
Anirudh Bhat ◽  
Gautam Mukherjee ◽  
Kishore T. Kashyap
Keyword(s):  
Monte Carlo Simulation ◽  
Particle Size ◽  
Grain Size ◽  
Monte Carlo ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Second Phase ◽  
Particle Sizes ◽  
Second Phase Particles ◽  
Average Grain Size

2D Potts model Monte Carlo simulation was carried out on a square lattice to investigate the effects of varying the size of second phase particles on the Zener limit of grain growth, in two-phase polycrystals. Simulations were carried out on a 1000^2 size matrix with Q-state of 64, dispersed with second phase particles of various sizes and surface fractions, and run to stagnation. Different grain growth parameters such as mean grain size, largest grain size, fraction of second phase particles lying on grain boundaries, etc., were computed for the pinned microstructures. The pinned average grain size or the Zener limit increased with increase in particle size, as per the classic Smith-Zener equation. The Zener limit scaled inversely with the square root of the particle fraction for all particle sizes, while it scaled exponentially with the fraction of second phase particles lying on the grain boundaries (ϕ), for all particle sizes tested.

Phase Field Model for Grain Growth with Second-Phase Particles of Stick Shape

2013 ◽  
Vol 741 ◽  
pp. 3-6 ◽  
Author(s):  
Wen Quan Zhou ◽  
Ying Juna Gao ◽  
Yao Liu ◽  
Zhi Rong Luo ◽  
Chuang Gao Huang
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Phase Field ◽  
Influence Factor ◽  
Phase Field Model ◽  
Phase Field Method ◽  
Second Phase ◽  
Triple Junctions ◽  
Pinning Effect ◽  
Second Phase Particles

The phase field method was applied to study the effect of second-phase particles (SPP) with different geometric orientations and shapes on grain growth. The results show that, in the grain growth process, most of the spherical second-phase particles located at triple junctions, while the stick SPPs located at the grain boundaries along the grain boundary. The second-phase particles are of the strong pinning effect on grain boundary and the limiting grain radius can be expressed by Zener relations. In the condition of the second-phase particles area fraction and size remaining the same, the stick SPPs are of more effective pinning on grain growth than that for spherical SPPs, and the orientation of disk second-phase particles is also an influence factor for pinning effect. Stick second-phase particles with multiple orientations can make a better pining effect than those with only one orientation.

Internal Stresses in Nanocrystalline Nickel and Nickel-Iron Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 1607-1611 ◽  
Author(s):  
J.D. Giallonardo ◽  
Uwe Erb ◽  
G. Palumbo ◽  
G.A. Botton ◽  
C. Andrei
Keyword(s):  
Grain Size ◽  
Internal Stress ◽  
Structural Difference ◽  
Intrinsic Stress ◽  
Internal Stresses ◽  
Second Phase ◽  
Nickel Iron ◽  
Second Phase Particles ◽  
Second Phases ◽  
Rule Out

Nanocrystalline metals are often produced in a state of stress which can adversely affect certain properties, e.g. corrosion resistance, wear, fatigue strength, etc. This stress is referred to as internal or “intrinsic” stress since it is not directly caused by applied loads. The structural causes of these stresses in nanocrystalline materials are not fully understood and are therefore an area of particular interest. The internal stresses of nanocrystalline Ni and Ni-16wt%Fe were measured and found to increase with the addition of iron. Characterization using HR-TEM revealed no signs of porosity, second phase particles, or a high density of dislocations. Both materials possessed well defined high-angle grain boundaries. The main structural difference between the two materials was found to be grain size and correspondingly, a decrease in grain size resulted in an increase in internal stress which supports the applicability of the coalescence theory. The current study also provides evidence to rule out the effect of voids (or porosity), dislocations, and second phases as possible causes of internal stress.

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