Microstructural Changes of Welded Zn-AI Alloy

1994 ◽  
Vol 367 ◽  
Author(s):  
Yao Hua Zhu
Keyword(s):  
Phase Transformation ◽  
Early Stage ◽  
Dendritic Structure ◽  
Metastable Phases ◽  
Grain Structure ◽  
Al Alloy ◽  
Cast State ◽  
Microstructural Changes ◽  
Fine Grain ◽  
Ageing Processes

AbstractExtruded eutectoid Zn-Al alloy was welded by a melt of the same eutectoid alloy. Two different microstructures were observed in the joint part and the bulk of the welded alloy. Typical dendritic structure of as cast Zn-Al alloy was observed in the joint part of the welded alloy. The bulk ofthe welded Zn-Al alloy appeared as fine grain structure. Two different metastable phases η'T decomposed from η's of chilled as cast state and η'E of extruded state were found to be unstable during early stage of ageing. A four phase transformation occurred after the decompositions of these two metastable phases of η'T. Microstructures of both joint part and bulk of the welded alloy were investigated parallely during ageing processes.

Microstructural changes in welded Zn–Al alloy

1996 ◽  
Vol 11 (3) ◽  
pp. 593-598 ◽  
Author(s):  
Yao Hua Zhu
Keyword(s):  
Phase Transformation ◽  
Dendritic Structure ◽  
Metastable Phases ◽  
Grain Structure ◽  
Al Alloy ◽  
Cast State ◽  
Microstructural Changes ◽  
Early Stages ◽  
Fine Grain ◽  
Eutectoid Alloy

Extruded eutectoid Zn–Al alloy was welded by a melt of the same eutectoid alloy. Two different microstructures were observed in the joint part and in the bulk of the welded alloy. Typical dendritic structure of as-cast Zn–Al alloy was observed in the joint part of the welded alloy. The bulk of the welded Zn–Al alloy appeared as fine grain structure. Two different metastable phases, η′T decomposed from η′s of the chilled as-cast state and η′E of the extruded state, were found to be unstable during the early stages of aging. A four-phase transformation occurred after the decompositions of these two metastable phases of η′T. Microstructures of both the joint part and bulk of the welded alloy were investigated simultaneously during the aging processes.

Grain Refinement of 6061 Al Alloy by the Modified Strain-Induced Melt- Activated(SIMA) Process for Semi-Solid Processing

2007 ◽  
Vol 119 ◽  
pp. 311-314 ◽  
Author(s):  
Young Buem Song ◽  
Chun Pyo Hong
Keyword(s):  
Grain Refinement ◽  
Grain Structure ◽  
Al Alloy ◽  
Fine Grained ◽  
Fine Grain ◽  
Fine Grained Structure ◽  
Size Uniformity ◽  
Sima Process ◽  
Semi Solid ◽  
6061 Al Alloy

The dynamic process of fine grain evolution of 6061 aluminum alloy during modified strain-induced, melt-activated (SIMA) process was studied. The modified SIMA process employed casting, two stage homogenization, warm multi-forging, and recrystallization and partial melting (RAP). Multi-forging was carried out at a strain rate of 9x10-3 s-1 to accumulate high strains, with decreasing temperature from 250 to 200 °C. The alloy multi-forged with the accumulated strain of about 12 and RAP at 640 °C for 10 min exhibited the uniform equiaxed recrystallized grain structure. Accordingly, it was evident that multi-forging was very effective on grain refinement and grain size uniformity. The present modified SIMA process was discussed as an alternative thermo-mechanical processing for preparing the alloys with fine grained structure for semi solid processing.

Microstructural Changes in As-Cast 7475 Al Alloy during Warm Sever Forging

2007 ◽  
Vol 539-543 ◽  
pp. 2922-2927 ◽  
Author(s):  
Alexandre Goloborodko ◽  
Taku Sakai ◽  
Oleg Sitdikov ◽  
Hiromi Miura
Keyword(s):  
Misorientation Angle ◽  
Large Strain ◽  
Grain Structure ◽  
Coarse Grained ◽  
Large Strains ◽  
Al Alloy ◽  
Deformation Bands ◽  
Microstructural Changes ◽  
Average Grain Size ◽  
Cumulative Strain

Microstructural changes taking place in an as-cast coarse-grained 7475 Al alloy was studied by using multidirectional forging (MDF) at a temperature of 250oC and at a strain rate of 3 × 10-4 s-1. The samples were deformed by MDF with a strain of 0.7 per pass up to cumulative strain (Σε) of 8.4. In the earlier stages of deformation, microstructural changes are mainly characterized by development of dislocation subboundaries with low-to-moderate misorientation angles. The misorientation angle initially increases with straining and reaches a plateau of around 3.7o in the strain range from 0.7 to 2.1, where new grain formation scarcely takes place in the original grain interiors. With further straining, grain fragmentation starts to occur accompanying with deformation bands developed at various directions, followed by rapid evolution of a new fine grain structure at large strain. The average grain size is around 1 μm at large strains and the average misorientation angle approaches a value of about 25o at Σε = 8.4.

Processing and Characterization of Ultra-Fine Grain Structure in Al Alloy by Equal Channel Angular Pressing

2012 ◽  
pp. 175-182
Author(s):  
Prasad P. Shanmugasundaram ◽  
Narayani Narasimhan ◽  
Balasivanadha Prabhu
Keyword(s):  
Equal Channel Angular Pressing ◽  
Grain Structure ◽  
Al Alloy ◽  
Angular Pressing ◽  
Fine Grain

scholarly journals Microstructure and Pitting Corrosion of Austenite Stainless Steel after Crack Arrest

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4025
Author(s):  
Zhuwu Zhang ◽  
Guangguo Pan ◽  
Yan Jiang ◽  
Song Chen ◽  
Song Zou ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Phase Transformation ◽  
Pitting Corrosion ◽  
Pulse Current ◽  
Crack Arrest ◽  
Current Treatment ◽  
Solidification Structure ◽  
Grain Structure ◽  
Fine Grain ◽  
Transformation Stress

With synergy of plastic deformation near crack tip and pulse current treatment, complex phase transformation and recrystallization occur in the metallographic structure, with the austenite transforming to fine grain structure and deformation-induced martensite; but, without the plastic deformation, the phase transformation, and recrystallization it was difficult for the crack arrest process to take place only undergoing the pulse current treatment. The nano-indentation experiment showed that the phase transformation region contained the maximum residual compressive stress consisting of four parts: the plastic stress, the explosion stress, the thermal stress, and the transformation stress, which was beneficial to restrain the crack growth. However, the solidification structure and the deformation-induced martensite structure was vulnerable to pitting corrosion through scanning microelectrode technology (SMET) and pitting corrosion experiment, but the pitting corrosion resistance could be improved through the solution heat treatment.

New Grain Formation in a Coarse-Grained 7475 Al Alloy during Severe Hot Forging

2004 ◽  
Vol 467-470 ◽  
pp. 421-428 ◽  
Author(s):  
Oleg Sitdikov ◽  
Tetsuo Sakai ◽  
Alexandre Goloborodko ◽  
Hiromi Miura ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Refinement ◽  
Hot Forging ◽  
Grain Boundary Sliding ◽  
Grain Structure ◽  
Coarse Grained ◽  
Al Alloy ◽  
Continuous Dynamic Recrystallization ◽  
Multidirectional Forging ◽  
Fine Grain ◽  
Continuous Dynamic

Strain-induced grain refinement in a coarse-grained 7475Al alloy was studied by means of multidirectional forging (MDF) carried out at T = 490oC under a strain rate of 3 x 10-4 s-1. Integrated flow curves exhibit significant work softening just after yielding, followed by steady-state-like behavior at high strains. The evolution of new fine grain structure during deformation can be assisted by grain-boundary sliding, resulting in frequent formation of high strain gradients and subsequently microshear bands in grain interiors. Microshear bands developed in various directions are intersected with each other, subdividing original grains into misoriented small domains. The number and the misorientation angle of microshear bands progressively increase during deformation, finally followed by their transformation into high-angle boundaries. It is concluded that grain refinement under hot MDF conditions occurs by a series of deformation-induced continuous reactions; that is essentially similar to continuous dynamic recrystallization.

Microstructure Development in a High Current Density NbTi Superconducting Composite

1985 ◽  
Vol 43 ◽  
pp. 186-189
Author(s):  
P. J. Lee ◽  
D. C. Larbalestier
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Cold Drawing ◽  
Heat Treatments ◽  
Grain Structure ◽  
Fine Grain ◽  
Boundary Film ◽  
Quantitative Basis ◽  
Cold Worked ◽  
Very High

Several features of the metallurgy of superconducting composites of Nb-Ti in a Cu matrix are of interest. The cold drawing strains are generally of order 8-10, producing a very fine grain structure of diameter 30-50 nm. Heat treatments of as little as 3 hours at 300 C (∼ 0.27 TM) produce a thin (1-3 nm) Ti-rich grain boundary film, the precipitate later growing out at triple points to 50-100 nm dia. Further plastic deformation of these larger a-Ti precipitates by strains of 3-4 produces an elongated ribbon morphology (of order 3 x 50 nm in transverse section) and it is the thickness and separation of these precipitates which are believed to control the superconducting properties. The present paper describes initial attempts to put our understanding of the metallurgy of these heavily cold-worked composites on a quantitative basis. The composite studied was fabricated in our own laboratory, using six intermediate heat treatments. This process enabled very high critical current density (Jc) values to be obtained. Samples were cut from the composite at many processing stages and a report of the structure of a number of these samples is made here.

CONTINUOUS-CAST 45-12 DUCTILE IRON

Alloy Digest ◽  
1989 ◽  
Vol 38 (4) ◽  
Keyword(s):  
Continuous Casting ◽  
Ductile Iron ◽  
Heat Treating ◽  
Grain Structure ◽  
Continuous Cast ◽  
Good Surface ◽  
Fine Grain ◽  
High Speeds ◽  
Good Surface Finish ◽  
Iron Grade

Abstract Ductile Iron grade 45-12 produced by continuous casting has consistent density and fine grain structure. It is the softest of the regular grades of ductile iron and it machines at high speeds with good surface finish. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, and tensile properties. It also includes information on heat treating, machining, and joining. Filing Code: CI-58. Producer or source: Federal Bronze Products Inc..

KETOS

Alloy Digest ◽  
1960 ◽  
Vol 9 (8) ◽  
Keyword(s):  
Physical Properties ◽  
Tensile Properties ◽  
Tool Steel ◽  
Heat Treating ◽  
Grain Structure ◽  
Steel Company ◽  
Fine Grain ◽  
Crucible Steel

Abstract KETOS is an oil-hardening non-deforming tool steel having deep hardening qualities with a fine grain structure. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as deformation. It also includes information on forming, heat treating, and machining. Filing Code: TS-96. Producer or source: Crucible Steel Company of America.

From symmetry to entropy: Crystal entropy difference strongly affects early stage phase transformation

2019 ◽  
Vol 115 (26) ◽  
pp. 264103
Author(s):  
C. H. Hu ◽  
Y. C. Chen ◽  
P. J. Yu ◽  
K. Y. Fung ◽  
Y. C. Hsueh ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Early Stage
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