In additively manufactured (AM) metallic materials, the fundamental interrelationships that exist between composition, processing, and microstructure govern these materials’ properties and potential improvements or reductions in performance. For example, by using AM, it is possible to achieve highly desirable microstructural features (e.g., highly refined precipitates) that could not otherwise be achieved by using conventional approaches. Simultaneously, opportunities exist to manage macro-level microstructural characteristics such as residual stress, porosity, and texture, the last of which might be desirable. To predictably realize optimal microstructures, it is necessary to establish a framework that integrates processing variables, alloy composition, and the resulting microstructure. Although such a framework is largely lacking for AM metallic materials, the basic scientific components of the framework exist in literature. This review considers these key components and presents them in a manner that h...

Microstructural Control of Additively Manufactured Metallic Materials

Bufadienolides from animal and plant sources.

Bufadienolides of plant and animal origin

Increasing the oxygen or the carbon dioxide concentration in the argon-based shielding gas leads to an increase in the weld metal oxygen content when the oxygen or carbon dioxide concentration is to be lower than 0.6 vol.% in the shielding gas. However, when the O2 or CO2 concentration is higher than 0.6 vol.% in the Ar-based shielding gas, the weld metal oxygen is maintained around 200 ppm–250 ppm. An inward Marangoni convection mode in the weld pool occurs when the weld metal oxygen content is more than 100 ppm. When it is lower than 100 ppm, the Marangoni convection would change to the outward direction and the weld shape varies from a deep narrow to a shallow wide shape. The effective ranges of O2 and CO2 concentrations for deep penetration are same. A heavy layer of oxides is formed when the O2 or CO2 concentration in the shielding gas is more than 0.6 vol.%. Based on the thermodynamic calculation of the equilibrium reactions of Fe, Si, Cr and Mn with oxygen in liquid iron for the oxide products, FeO, SiO2 ,C r 2O3 and MnO and the experimental oxygen content in the weld metal, Cr2O3 and SiO2 oxides are possibly formed at the periphery area of the liquid pool surface under the arc column during the welding process. One model is proposed to illustrate the role of the oxide layer on the Marangoni convection on the pool surface at elevated temperature. The heavy oxide layer inhibited the fluid flow induced by the Marangoni convection and also became a barrier for the oxygen absorption into the molten weld pool. © 2004 Elsevier B.V. All rights reserved.

http://www.jwri.osaka-u.ac.jp/~dpt9/MSE(2004)O2CO2.pdf

Marangoni convection and weld shape variations in Ar-O2 and Ar-CO2 shielded GTA welding

Cytotoxic profile of natural and some modified bufadienolides from toad Rhinella schneideri parotoid gland secretion.

The nitrogen absorption by iron, Fe-20Cr-10Ni and SUS329J1 stainless steel YAG laser welding in the atmosphere of Ar-N2 mixture gas was investigated in comparison with those during arc welding using the same materials as in this experiment and equilibrium data. Although the nitrogen contents of YAG laser weld metal increase with the nitrogen partial pressure were as well as those of arc weld metal of arc welding, the nitrogen content during YAG laser welding were quite less than those during arc welding. Blowholes can not be observed in Fe-20Cr-10Ni and SUS329J1 stainless steel and can only be found in iron at lower nitrogen partial pressure during YAG laser welding. A discussion on the difference in nitrogen absorption between YAG Laser and arc welding has suggested that small amount of nitrogen absorption results from less opportunity of nitrogen to touch the surface of molten metal due to the active evaporation of metal which covers the major surface of molten metal during laser welding metal. Additionally, the short-time thermal cycle compared with arc welding may bring insufficient nitrogen absorption in the weld metal during cooling. It can be considered that the nitrogen absorption during YAG laser welding is basically different from that during arc welding.

/pdf/nitrogen-absorption-by-iron-and-stainless-steels-during-yag-4hw7z1r4ja.pdf

Nitrogen Absorption by Iron and Stainless Steels during YAG Laser Welding

The occurrence of marinobufagin 3-succinyl-L-arginine and 3-glutaryl-L-arginine esters, and telocinobufagin 3-glutaryl-L-arginine ester, together with seven known bufogenins, in the skin of Bufo bankorensis BORBOUR, is reported. The structures were elucidated by degradative means and/or direct comparison with authentic samples. These compounds were assayed for inhibitory activity towards guinea pig heart Na+, K+-adenosine triphosphatase.

/pdf/occurrence-of-marinobufotoxin-and-telocinobufotoxin-homologs-5fyey6zysm.pdf

Occurrence of marinobufotoxin and telocinobufotoxin homologs in the skin of Bufo bankorensis BORBOUR.

The authors have been engaged in an extensive program of fundamental and systematic research intended to clarify the effects of alloying elements on the oxygen absorption during arc welding process. In this report, the outline of an oxygen absorption behavior in iron and steel weld metal during Gas-Metal-Arc welding process is described on the basis of the authors group's data. Initially the oxygen absorption behavior of the pure iron weld metal is thermodynamically analyzed. The similar investigations are carried out for Fe-Si, Fe-Mn, Fe-Al, Fe-Ti, Fe-Cr and Fe- Ni weld metat, and the results are analyzed. Finally, the oxygen absorption behavior of the mild steel is also described.

Oxygen Absorption in Iron and Steel Weld Metal

Pure iron plates were welded using pure iron electrode wire in a controlled arc atmosphere. Effects of the oxidizing gas partial pressure in the welding atmospheres of Ar-O2 and Ar-CO2 gas mixture and welding conditions on the oxygen contents and the nonmetallic inclusions of the iron weld mteals were systematically studied.The results are as follows:1. The mean temperature of the iron weld pool is about 1910 K.2. The oxygen contents and the inclusions of the iron weld metals decrease with increasing the welding current and increase with increasing the arc voltage.3. The oxygen contents and the inclusions of the iron weld metals decrease slightly with increaseing the traveling speed.4. In Ar-O2 welding atmosphere, the oxygen contents and the inclusions of the iron weld metals increase with increasing the oxygen partial pressure, but the oxygen contents become constant value at about 0.26 wt.% in high oxygen partial pressure atmosphere. In Ar-CO2 welding atmosphere, the oxygen contents and the inclusions of the iron weld metals increase with increasing the carbon dioxide partial pressure. The oxide inclusions are seemed to be FeO.5. Behavior of the oxygen absorption into the iron weld metal is discussed using thermodynamic data.

Oxygen Absorption and Oxide Inclusion of Iron Weld Metal during Arc Welding

Pure iron plates were welded using Fe-Ti alloy electrode wires in a controlled arc atmosphere. The effects of titanium on the oxygen contents and non-metallic inclusions in the weld metals were investigated under various welding conditions in Ar-O2 and Ar-CO2 welding atmospheres.The oxygen contents of the Fe-Ti weld metals increase with an increasing the partial pressure of oxidizing gases and decrease with an increasing titaninum contents in the weld metals. The oxygen contents of the weld metals welded in Ar-CO2 are lower than those in Ar-O2. The non-metallic inclusions are mainly titanium-oxide. The compositions of the non-metallic inclusion in the Fe-Ti weld metals take various form of Ti2O3, TiO2, FeO-TiO2, 2FeO-TiO2 and FeO depending to the increasing oxygen content and decreasing titanium content of the weld metals. Behavior of the oxygen absorption by the steel weld metal is discussed using thermodynamic data.

https://www.jstage.jst.go.jp/article/qjjws1983/8/1/8_1_91/_pdf

Yoshihiro Sato

Papers

Nitrogen Absorption by Iron and Stainless Steels during YAG Laser Welding

Occurrence of marinobufotoxin and telocinobufotoxin homologs in the skin of Bufo bankorensis BORBOUR.

Oxygen Absorption in Iron and Steel Weld Metal

Oxygen Absorption and Oxide Inclusion of Iron Weld Metal during Arc Welding

Oxygen Absorption and Oxide Inclusion of Fe-Cr Weld Metal.