Effect of thermomechanical processing on mechanical properties of Fe-16 at. % Al alloy

An iron-aluminum alloy containing 16 at. % Al, which is essentially free from environmental effect on its ductility, has been developed. This alloy has over 20% elongation at room temperature. This paper presents in detail the effect of vacuum versus air melting on the properties of Fe-16 at. % Al alloy. The comparative results have shown air-induction melting to produce lower room-temperature ductility for the identical processing steps. Additional processing steps required to improve the ductility of air-melted material are also identified

Commercialization of nickel and iron aluminides

Metallurgists are taught that intermetallics are brittle phases and should be avoided in alloys of commercial interest. This education is so deeply rooted that irrespective of significant advances made in ductilization of aluminides,the road to their acceptance commercialization is extremely difficult. This paper identifies the requirements for commercialization of any new alloys and reports the activities carried out to commercialize Ni and Fe aluminides. The paper also identifies areas which meet the current commercialization requirements and areas needing additional effort

Characteristics of a multicomponent Nb-Ti-Al alloy via industrial-scale practice

Within the spectrum of advanced intermetallic materials, an alloy containing 44Nb-35Ti-6Al-5Cr-8V-1W-0.5Mo-0.3Hf (at. %) was investigated in the industrial-scale produced condition. The alloy was tensile tested in air from room temperature to 1,000 C and in vacuum at 750 and 850 C. Results of this study have shown that the alloy can be commercially produced and has adequate ductility for its secondary processing even at an oxygen level of 1,160 wppm. The alloy has room temperature ductility of 16% and superplastic elongation of 244% at 1,000 C. This alloy shows low intermediate temperature (600--850 C) ductility when tested in air. The vacuum testing revealed that the low ductility is associated within oxygen embrittlement phenomenon. It is expected that such an embrittlement can be taken care of by an oxidation resistant coating. The alloy also possesses superior strength to similar alloys in this class. Results of this investigation suggest a strong potential for consideration of this alloy to exceed the useful temperature range of nickel-base superalloys

Characteristics of a multicomponent Nb–Ti–Al alloy via industrial-scale practice

Within the spectrum of advanced intermetallic materials, an alloy containing 44Nb-35Ti-6Al-5Cr-8V-1W-0.5Mo-0.3Hf (at. %) was investigated in the industrial-scale produced condition. The alloy was tensile tested in air from room temperature to 1,000 C and in vacuum at 750 and 850 C. Results of this study have shown that the alloy can be commercially produced and has adequate ductility for its secondary processing even at an oxygen level of 1,160 wppm. The alloy has room temperature ductility of 16% and superplastic elongation of 244% at 1,000 C. This alloy shows low intermediate temperature (600--850 C) ductility when tested in air. The vacuum testing revealed that the low ductility is associated within oxygen embrittlement phenomenon. It is expected that such an embrittlement can be taken care of by an oxidation resistant coating. The alloy also possesses superior strength to similar alloys in this class. Results of this investigation suggest a strong potential for consideration of this alloy to exceed the useful temperature range of nickel-base superalloys

Development of promiscous rhizobia for diverse rabi legumes (Chickpea, Pea and Lentil)

Conjugation between microsymbiont was used to create genetic variations in rhizobia for diverse rabi legumes (chickpea, pea and lentil) with better characteristics in nodulation and nitrogen fixation process. Ten antibiotics were used as selectable markers for the screening of twenty four bacterial strains to be used in mating experiments for obtaining transconjugants. All bacterial strains were sensitive to gentamycin and resistant to streptomycin, kanamycin and sulphanilamide. Total five fusants were obtained from each rhizobial cross combination with the help of electro-poration. Modified transconjugants, rhizobial strains had promiscuous infection with 50-122% more nodules showed significant increase in shoot fresh weight, dry weight and total nitrogen content in chickpea, pea and lentil plants. Electrofusantsrhizobial strains improved shoot nitrogen content up to 67% in lentil and 54% in pea and chickpea plants. The amount of nitrogen fixed in chickpea was highest (3.71gm) by transconjugants DP-C6- HLN followed by DP-C6-HP14 (3.56gm). Transconjugants DP-HP14-HLN fixed the highest amount of nitrogen (3.92gm) in pea and 4.06gm in lentil plants. Plasmids were also analyzed in order to characterize their role in the evolution of rhizobial symbionts and their involvement in symbiotic behaviour. The developed Rhizobium strains with improved symbiotic association and ability to infect across strict specificity for host legumes would be of great help for the farming community at large

Development of Stronger and More Reliable Cast Austenitic Stainless Steels (H-Series) Based on Scientific Design Methodology

The goal of this program was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and upper use temperature by 86 to 140 F (30 to 60 C). Meeting this goal is expected to result in energy savings of 38 trillion Btu/year by 2020 and energy cost savings of $185 million/year. The higher strength H-Series of cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat-treating industry. The project was led by Duraloy Technologies, Inc. with research participation by the Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies. Energy Industries of Ohio (EIO) was also a partner in this project. Each team partner had well-defined roles. Duraloy Technologies led the team by identifying the base alloys that were to be improved from this research. Duraloy Technologies also provided an extensive creep data base on current alloys, provided creep-tested specimens of certain commercial alloys, and carried out centrifugal casting and component fabrication of newly designed alloys. Nucor Steel was the first partner company that installed the radiant burner tube assembly in their heat-treating furnace. Other steel companies participated in project review meetings and are currently working with Duraloy Technologies to obtain components of the new alloys. EIO is promoting the enhanced performance of the newly designed alloys to Ohio-based companies. The Timken Company is one of the Ohio companies being promoted by EIO. The project management and coordination plan is shown in Fig. 1.1. A related project at University of Texas-Arlington (UT-A) is described in Development of Semi-Stochastic Algorithm for Optimizing Alloy Composition of High-Temperature Austenitic Stainless Steels (H-Series) for Desired Mechanical and Corrosion Properties (ORNL/TM-2005/81/R1). The final report on another related project at the University of Tennessee by George Pharr, Easo George, and Michael Santella has been published as Development of Combinatorial Methods for Alloy Design and Optimization (ORNL/TM-2005-133). The goal of the project was to increase the high-temperature strength by 50$185 million/year. The goal of the project was achieved by using the alloy design methods developed at ORNL, based on precise microcharacterization and identification of critical microstructure/properties relationships and combining them with the modern computational science-based tools that calculate phases, phase fractions, and phase compositions based on alloy compositions. The combined approach of microcharacterization of phases and computational phase prediction would permit rapid improvement of the current alloy composition of an alloy and provide the long-term benefit of customizing alloys within grades for specific applications. The project was appropriate for the domestic industry because the current H-Series alloys have reached their limits both in high-temperature-strength properties and in upper use temperature. The desire of Duraloy's industrial customers to improve process efficiency, while reducing cost, requires that the current alloys be taken to the next level of strength and that the upper use temperature limit be increased. This project addressed a specific topic from the subject call: to develop materials for manufacturing processes that will increase high-temperature strength, fatigue resistance, corrosion, and wear resistance. The outcome of the project would benefit manufacturing processes in the chemical, steel, and heat-treating industries

Twin boundary cavitation in aged type 304 stainless steel

A transition from grain to twin boundary cavitation was observed in aged- and-creep-tested type 304 stainless steel. Evidence of twin boundary cavitation has also been observed for unaged material under certain test conditions. This same behavior was also found in aged type 316 stainless steel. Several possible reasons have been suggested for the absence of frequently observed grain boundary cavitation. (auth

Twin boundary cavitation in aged type 304 stainless steel

A transition from grain to twin boundary cavitation was observed in aged- and-creep-tested type 304 stainless steel. Evidence of twin boundary cavitation has also been observed for unaged material under certain test conditions. This same behavior was also found in aged type 316 stainless steel. Several possible reasons have been suggested for the absence of frequently observed grain boundary cavitation. (auth

High precision temperature controlling AGPase in wheat affecting yield and quality traits

Adenosine diphosphate glucose pyrophosphorylase (AGPase) is the rate limiting enzyme of starch biosynthesis that directly affects the wheat productivity. AGPase and grain growth rate (GGR) discerned to be following strict temperature regimen in wheat disomic chromosome substitution (DCS) lines. The first half of grain filling period had chromosome 1B and 2D as prominent players, whereas second half was mainly controlled by chromosomes 6A and 5B. Chromosome 2D had major contribution towards yield in a specific temperature range of 23 ± 1.5 °C during initial stages of grain filling which can serve as an effective early screening tool for terminal heat tolerance in wheat. Chromosome 2D with highest amylose content can also be utilized to produce low digestibility flour. Grain yield was found to be significantly associated with spikes/plant, grains/spike, grain weight/spike and plant biomass. Further, path analysis indicated that though grains/spike had less direct effect on grain yield but its indirect impact on grain yield via AGPase-21 activity was high

Tensile and creep properties of type 316 stainless steel

A mechanical property characterization test program on type 316 stainless steel is in progress at ORNL to furnish information for (a) the formulation and verification of constitutive equations, (b) setting failure criteria, and (c) verification of ASME design stresses and rules