scholarly journals The influence of Mg and Mn content on abnormal grain growth in AA5182 type alloys

10.30544/463 ◽  
2020 ◽  
Vol 25 (04) ◽  
pp. 315-323
Author(s):  
Tamara Radetić ◽  
Miljana Popović ◽  
Bojan Gligorijević ◽  
Ana Alil ◽  
Endre Romhanji
Keyword(s):  
Cold Rolling ◽  
Grain Growth ◽  
Processing Parameters ◽  
Abnormal Grain Growth ◽  
Strong Anisotropy ◽  
Grain Boundary Mobility ◽  
Zener Pinning ◽  
Cold Rolling Reduction ◽  
Mn Content ◽  
Aa5182 Alloy

The occurrence of abnormal grain growth (AGG) in AA5182 alloy during annealing imposes severe restrictions on processing parameters and deteriorates mechanical properties. In this work, we investigated the effect of chemical composition on the appearance of abnormal grain growth by varying Mg and Mn content in the range of composition limits for standard AA5182 alloy, 4.0-5.0% Mg, and 0.2-0.5% Mn, respectively. Thermo-mechanical processing of alloys included cold rolling with reductions ranging from 40 to 85%, followed by annealing in the temperature range from 350 to 520 °C. The results showed that the rise in alloying elements content drives the onset of abnormal grain growth toward higher temperatures. The increase in the cold rolling reduction degree promotes abnormal grain growth and lowers its onset temperature. Abnormal grain growth and grain boundary mobility showed strong anisotropy related to rod-like shape and alignment of Al6Mn(Fe) dispersoids through Zener pinning.

scholarly journals Precipitation Criterion for Inhibiting Austenite Grain Coarsening during Carburization of Al-Containing 20Cr Gear Steels

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 504
Author(s):  
Huasong Liu ◽  
Yannan Dong ◽  
Hongguang Zheng ◽  
Xiangchun Liu ◽  
Peng Lan ◽  
...  
Keyword(s):  
Grain Growth ◽  
Abnormal Grain Growth ◽  
Grain Structure ◽  
Pinning Force ◽  
Grain Coarsening ◽  
Zener Pinning ◽  
Austenite Grain ◽  
Composition Optimization ◽  
Gear Steels ◽  
Grain Growth Behavior

AlN precipitates are frequently adopted to pin the austenite grain boundaries for the high-temperature carburization of special gear steels. For these steels, the grain coarsening criterion in the carburizing process is required when encountering the composition optimization for the crack-sensitive steels. In this work, the quantitative influence of the Al and N content on the grain size after carburization is studied through pseudocarburizing experiments based on 20Cr steel. According to the grain structure feature and the kinetic theory, the abnormal grain growth is demonstrated as the mode of austenite grain coarsening in carburization. The AlN precipitate, which provides the dominant pinning force, is ripened in this process and the particle size can be estimated by the Lifshitz−Slyosov−Wagner theory. Both the mass fraction and the pinning strength of AlN precipitate show significant influence on the grain growth behavior with the critical values indicating the grain coarsening. These criteria correspond to the conditions of abnormal grain growth when bearing the Zener pinning, which has been analyzed by the multiple phase-field simulation. Accordingly, the models to predict the austenite grain coarsening in carburization were constructed. The prediction is validated by the additional experiments, resulting in accuracies of 92% and 75% for the two models, respectively. Finally, one of the models is applied to optimize the Al and N contents of commercial steel.

Effects of Cold Work on Abnormal Grain Growth During Simulated Carburizing of 4121 Steel Containing Nb

2021 ◽  
Author(s):  
Sukjin Lee ◽  
Eun Jung Seo ◽  
Robert L. Cryderman ◽  
David K. Matlock ◽  
John G. Speer
Keyword(s):  
Grain Growth ◽  
Cold Work ◽  
Abnormal Grain Growth ◽  
Reduction Ratio ◽  
Cold Forging ◽  
Cold Rolling Reduction ◽  
Martensitic Microstructure ◽  
Cold Rolled ◽  
Austenite Grain Growth ◽  
Nb Addition

Abstract Precision cold-forging processes are used to produce near-netshape parts that may then be carburized. During carburization thermal cycles, abnormal grain growth (AGG) after cold forging is known to develop microstructures which limit fatigue strength. In the present study, a small 0.04 wt.% Nb addition was made to a low-alloyed AISI 4121 steel containing 0.3 wt.% Mo. Subcritically annealed specimens were cold rolled (to simulate cold forging) at selected reduction ratios up to 50%, heated according to a simulated gas carburizing cycle at 930 °C, and water quenched to produce a final martensitic microstructure. The number density of abnormally grown grains increased rapidly as the cold rolling reduction ratio increased from 0 to 10%. With a further increase in reduction ratio, the extent of AGG decreased and was absent in samples subjected to the maximum reduction ratio of 50%. The evolution of fine (Nb, Mo)(C,N) precipitates at various stages of processing was characterized by thermodynamic calculations and electron microscopy and compared to the occurrence of abnormal austenite grain growth. The significance of these results for controlling AGG and thus optimizing fatigue performance in commercially-produced cold-forged and carburized components is discussed.

New Understanding of Abnormal Grain Growth Approached by Solid-State Wetting along Grain Boundary or Triple Junction

2004 ◽  
Vol 467-470 ◽  
pp. 745-750 ◽  
Author(s):  
Nong Moon Hwang
Keyword(s):  
Solid State ◽  
Grain Boundary ◽  
Grain Growth ◽  
Triple Junction ◽  
Boundary Energy ◽  
Growth Front ◽  
Abnormal Grain Growth ◽  
Boundary Mobility ◽  
Grain Boundary Mobility ◽  
Mc Simulation

Although it has been generally believed that the advantage of the grain boundary mobility induces abnormal grain growth (AGG), it is suggested that the advantage of the low grain boundary energy, which favors the growth by solid-state wetting, induces AGG. Analyses based on Monte Carlo (MC) simulation show that the approach by solid-state wetting could explain AGG much better than that by grain boundary mobility. AGG by solid-state wetting is supported not only by MC simulations but also by the experimental observation of microstructure evolution near or at the growth front of abnormally growing grain. The microstructure shows island grains and solid-state wetting along grain boundary and triple junction.

The Effects of Dopants on Surface-Energy-Driven Secondary Grain Growth in Ultrathin Si Films

1985 ◽  
Vol 54 ◽  
Author(s):  
H.-J. Kim ◽  
C. V. Thompson
Keyword(s):  
Surface Energy ◽  
Grain Growth ◽  
Ultrathin Films ◽  
Abnormal Grain Growth ◽  
Growth Enhancement ◽  
Grain Boundary Mobility ◽  
Additional Doping ◽  
Heavily Doped ◽  
Si Films ◽  
P Type

ABSTRACTSecondary or abnormal grain growth has been observed in ultrathin films of silicon (<120nm) that were heavily doped with phosphorous or arsenic. This grain growth leads to grains which are much larger than the film thickness (>50x) and which have uniform (111) texture. This abnormal grain growth is believed to be driven, in part, by surface energy minimization and hence is termed surface-energy-driven secondary grain growth.It was found that n-type dopants, phosphorous and arsenic, markedly enhance the rate of secondary grain growth as seen through a lowering of the temperature required for significant growth. On the other hand, boron (a p-type dopant) appears to neither markedly increase nor decrease the rate of grain growth. Enhancement caused by phosphorous or arsenic is thought to stem from increases in the mobility of the grain boundaries. Enhancement of grain boundary mobility was found to be compensated (reduced or eliminated) by additional doping with boron.

Abnormal Grain Growth Approached by Sub-Boundary Enhanced Solid-State Wetting

2012 ◽  
Vol 715-716 ◽  
pp. 542-542
Author(s):  
Nong Moon Hwang
Keyword(s):  
Solid State ◽  
Cold Rolling ◽  
Grain Growth ◽  
Triple Junction ◽  
Secondary Recrystallization ◽  
Growth Front ◽  
Abnormal Grain Growth ◽  
Low Energy ◽  
Polycrystalline Materials ◽  
Goss Texture

Abnormal grain growth (AGG), which is also called the secondary recrystallization, often takes place after primary recrystallization of deformed polycrystalline materials. A famous example is the evolution of the Goss texture after secondary recrystallization of Fe-3%Si steel. A selective AGG of Goss grains has remained a puzzle over 70 years in the metallurgy community since its first discovery by Goss in 1935. We suggested the sub-boundary enhanced solid-state wetting as a mechanism of selective AGG of Goss grains. According to this mechanism, if Goss grains have sub-boundaries of low energy, they have an exclusively high probability to grow by solid-state wetting along a triple junction compared with other grains without sub-boundaries. This aspect has been confirmed by Monte-Carlo and Phase Field Model simulations. The simulations showed that if the abnormally-growing grain has a high fraction of low energy boundaries with the matrix grains, it favors the sub-boundary enhanced solid-state wetting and produces many island and peninsular grains frequently observed near the growth front of abnormally-growing Goss grains. For example, the {111}<112> orientation has a S9 relationship with a Goss grain. Therefore, grains with the {111}<112> orientation provide a favorable condition for sub-boundary enhanced solid-state wetting. Three or four-sided grains with convex-inward boundaries, which are observed on a two-dimensional section of polycrystalline structures, are not shrinking but are growing, indicating that they are growing by wetting along a triple junction. These and other microstructural evidences of solid-state wetting could be observed relatively easily near the growth front of abnormally-growing Goss grains. The existence of sub-boundaries exclusively in abnormally-growing Goss grains has been experimentally confirmed. In order to understand why only Goss grains have sub-boundaries, the cold rolling process of the hot-rolled Fe-3%Si steel was analyzed by finite element method (FEM). The analysis showed that a small portion of Goss grains formed during hot rolling survives after cold rolling; the survived Goss grains have the lowest stored energy and are expected to undergo only recovery without recrystallization, producing sub-boundaries.

scholarly journals Strain Induced Abnormal Grain Growth in Nickel Base Superalloys

2013 ◽  
Vol 753 ◽  
pp. 321-324 ◽  
Author(s):  
Nathalie Bozzolo ◽  
Andrea Agnoli ◽  
Nadia Souaï ◽  
Marc Bernacki ◽  
Roland E. Logé
Keyword(s):  
Grain Growth ◽  
Boundary Migration ◽  
Energy Difference ◽  
Abnormal Grain Growth ◽  
Second Phase ◽  
Zener Pinning ◽  
Second Phase Particles ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Key Parameter

Under certain circumstances abnormal grain growth occurs in Nickel base superalloys during thermomechanical forming. Second phase particles are involved in the phenomenon, since they obviously do not hinder the motion of some boundaries, but the key parameter is here the stored energy difference between adjacent grains. It induces an additional driving force for grain boundary migration that may be large enough to overcome the Zener pinning pressure. In addition, the abnormal grains have a high density of twins, which is likely due to the increased growth rate.

scholarly journals Mobility Driven Abnormal Grain Growth in the Presence of Particles

2012 ◽  
Vol 715-716 ◽  
pp. 930-935 ◽  
Author(s):  
E. Fjeldberg ◽  
Elizabeth A. Holm ◽  
Anthony D. Rollett ◽  
Knut Marthinsen
Keyword(s):  
Monte Carlo ◽  
Grain Growth ◽  
Driving Force ◽  
Monte Carlo Model ◽  
Abnormal Grain Growth ◽  
Volume Fractions ◽  
Zener Pinning ◽  
Inhibiting Effect

Simulation of mobility-driven abnormal grain growth in the presence of particles in a 3D Potts Monte Carlo model has been investigated, and even though the driving force in this case is identical to normal grain growth, Zener pinning does not occur. Instead the particles seem merely to have a small inhibiting effect on the number of abnormal grains, and this effect only has a noticeable influence for volume fractions of particles above 5 vol%.

On the Abnormal Grain Growth in Pure Magnesium

2018 ◽  
Author(s):  
Risheng Pei ◽  
Sandra Korte-Kerzel ◽  
Talal Al-Samman
Keyword(s):  
Grain Growth ◽  
Abnormal Grain Growth ◽  
Pure Magnesium
Sign in / Sign up

Export Citation Format

Share Document