Grain Growth Mechanism of Lamellar-Structure High-Purity Nickel via Cold Rolling and Cryorolling during Annealing

High-purity (99.999%) nickel with lamellar-structure grains (LG) was obtained by room-temperature rolling and cryorolling in this research, and then annealed at different temperatures (75 °C, 160 °C, and 245 °C). The microstructure was characterized by transmission electron microscopy. The grain growth mechanism during annealing of the LG materials obtained via different processes was studied. Results showed that the LG high-purity nickel obtained by room-temperature rolling had a static discontinuous recrystallization during annealing, whereas that obtained by cryorolling underwent static and continuous recrystallization during annealing, which was caused by the seriously inhibited dislocation recovery in the rolling process under cryogenic conditions, leading to more accumulated deformation energy storage in sheets.

DEVELOPMENT OF CONTINUOUS ANTI-SOLVENT RECRYSTALLIZATION METHOD TO PRODUCE CEFTRIAXONE SODIUM NANO CRYSTALS INJECTION USING CERAMIC FILTRATION

The aim: In this work we developed a method of continuous recrystallization to meet industrial requirements. Materials and methods: Continuous recrystallization method was investigated using porous ceramic filter for water purification with pour size less than 1 μm, that ensures high mixing rate of ethanol and water. Results and conclusions: The results of experiments using crystallization through ceramic filter, gives superior products in particle size, and produced needle shaped ceftriaxone crystals form, that showed significant improvement in dissolution time and obtained ceftriaxone sodium powder to be reconstituted in injectable formula that give clear solution without insoluble microparticles.

Microstructure Analysis of IS2062 Plates Cladded with SS2594 by TIG Welding Process

The power requirement of industries has been growing like anything now-a-days. The components involved in the production of power have also attracted more attention in industrial revolution. The present work focuses on improving the hardness and shear resistance of IS2062 work material used in the manufacturing of fire tubes in thermal power plants. The cladding of surface was carried out by Tungsten Inert Gas (TIG) welding with the use of SS2594 duplex steel as surface coating material. Hardness test results revealed that cladding process have raised the value from 170 to 411. Microstructural analysis has revealed the formation of refined grains at the clad zone due to continuous recrystallization of martensite. It has happened because of higher gas flow rate during welding. Macroscopic analysis has proved the increase in current during the process improved the diffusion of SS2594 material into the base metal IS2062.

On the Strength of a 316L-Type Stainless Steel Subjected to Cold or Warm Rolling Followed by Annealing

The ultrafine-grained microstructures and their effect on the yield strength of a 316L-type austenitic stainless steel processed by large strain cold/warm rolling and subsequent annealing were studied. A kind of continuous recrystallization developed during annealing, resulting in the evolution of uniform ultrafine-grained microstructures with relatively high residual dislocation densities. The development of such microstructure at 973 K led to excellent combination of tensile properties including high yield strength (σ0.2 > 900 MPa) and satisfactory plasticity (δ > 15%). A unique power law function between the annealed grain size and the dislocation density with a dislocation density exponent of −0.5 was obtained for these continuously recrystallized microstructures. A physically justified explanation of the observed structural/substructural strengthening is introduced.

Texture formation process of 6063-type aluminium alloy during hot extrusion

This study investigated the texture formation process of A6063 alloy hot extruded material using electron backscatter diffraction (EBSD) measurements. The cube component that becomes the main orientation during hot extrusion was formed near the bearing inflow in the extrusion chamber and grew with continuous recrystallization. The Goss component with the same ED // <100> relationship as the cube component was not formed in the chamber or the bearing but was formed by discontinuous recrystallization after passing through the bearing. The TD // <111> orientation component of the surface layer was formed in the bearing and then grew with discontinuous recrystallization. However, because the internal cube and Goss components expanded preferentially, the surface layer TD // <111> components were replaced by the cube and Goss components after passing through the bearing. The cubic texture formation of extruded aluminium alloys is noted to be analogous to the formation of rolling sheet materials, formed by recovery and recrystallization from a plane strain deformation structure. However, for the A6063 alloy extruded under conditions close to industrial production, the cube components were mainly formed by recovery and continuous recrystallization.

Tempering of deformed and as-quenched martensite in structural steel

Annealing of deformed martensite (high-temperature tempering) in St37 steel was studied. Different reductions in thickness were considered and compared with the behavior of as-quenched martensite during tempering. tempering of the asquenched martensite was accompanied by the formation of carbide particles, incomplete disappearance of the lath martensite morphology, and continuous decrease in hardness until reaching low values. However, during tempering of the cold rolled martensite, the precipitation of carbides in the lamellar structure, development of distinct equiaxed ultrafine grains through a continuous recrystallization mechanism, and a sudden hardness drop were characterized. The importance of cold rolling reduction and its amount were also discussed.

Nanostructuring of 2xxx Aluminum Alloy under Cryorolling to High Strains

The structure transformations in the D16 (2024) aluminum alloy caused by isothermal rolling with effective strain up to e ~3.5 at a temperature of liquid nitrogen were investigated. It is shown that under straining to e ~2.0 the dislocation structure containing cells of the nanometric size is formed. At higher strains the dynamic recovery and continuous recrystallization result in the development of a mixed nano(sub) grain structure, which after e ~3.5 is characterized by the size and volume fraction of grains ~ 150 nm and 40-45%, respectively. Nature of the alloy structure transformations is discussed.