Subsequent Cold Research Articles

Effect of the Strain Kind on the Texture and Microstructure of Low-Alloyed Steel

Crystallographic texture and microstructure of low-alloyed steel after twist extrusion (TE) and subsequent cold rolling along and across the TE axis were studied. The double axial cylindrical texture with axes 110 and 100 parallel to the TE axis and the vortex-like microstructure are formed in the steel during the TE. The subsequent rolling of extruded steel along the TE axis promotes the forming of typical steel rolling texture as well as the microstructure with elongated grains in rolling direction. Typical steel rolling texture as well as the equiaxed microstructure is formed in extruded steel after rolling in the direction transverse to the TE axis. The mechanisms of formation of the texture are discussed.

Stimulation of germination in dormant seeds of Juniperus polycarpos by stratification and hormone treatments

Dormancy in Juniperus polycarpos (K. Koch) seeds is a major hurdle for production of the desired quantity of seedlings in nurseries for restoration purpose. Thus, the aim of this study was to develop an optimal dormancy breaking treatment and subsequent stimulation of germination. The treatments applied were cold stratification at 1 °C for 4, 8, 12, and 16 weeks; warm stratification at 20 °C for 4, 8, 12, and 16 weeks followed by 12 weeks of cold stratification; exogenous application of 250, 500, and 1000 ppm gibberellic acid (GA3) and 6-Benzylamino purine (BAP); and a combination of 500 ppm hormones and cold stratification. The results show significant differences in germination between cold and warm-cold stratification, length of stratification and their interaction (p < 0.01). Warm stratification for 16 weeks followed by 12 weeks of cold stratification induced 72 % of the seeds to germination in 12 days compared with 16-week cold-stratification alone (42 %) and the control (8 %). Exogenous application of GA3 and BAP alone or in combination with cold stratification resulted in less than 50 % germination though significantly (p < 0.01) higher than the control. Apparently, the hormone treatments alone or in combination with cold stratification are not effective in completely breaking dormancy and stimulation of germination. The findings suggest that J. polycarpos seeds may possess intermediate simple morpho-physiological dormancy, which could be an adaptive mechanism for relatively warmer autumn temperature during seed maturation and the subsequent cold winter temperature under natural conditions.

Cold rolled tungsten (W) plates and foils: Evolution of the microstructure

This paper is the first part of our series on ultrafine-grained (UFG) tungsten produced by cold rolling. The aim of our project is to investigate the correlation between microstructure, mechanical properties and deformation mechanisms in UFG tungsten, a material interesting for future high-temperature applications. For this purpose, a batch of tungsten sheets with different thicknesses has been produced by subsequent cold rolling out of a single sintered compact.The aim of this paper is to characterise the microstructure of the as-received tungsten sheets. Quantitative grain size analysis by EBSD confirms a grain refinement by cold rolling well down into the UFG-regime, reaching 240nm in the S-direction for the 100μm foil. The grain refinement comes with an increase in the number of HAGBs, while LAGBs show no correlation with the degree of deformation introduced by cold rolling. All plates are distinctively textured, the main texture being the {001}〈110〉-orientation (rotated cube texture).Vickers microhardness measurements confirm a steady increase in hardness with advanced rolling up to 687kg/mm2 for the 100μm foil. This indicates that the one-dimensional grain refinement to UFG by cold rolling is sufficient to achieve properties comparable to other UFG tungsten specimens. Therefore, it can be concluded that the batch of samples introduced in this paper will be fit to investigate the evolution of mechanical properties and deformation mechanisms in correlation with the microstructure.

Effect of Rolling on High-Cycle Fatigue and Fracture of an Al – Mg – Sc Alloy

The tensile strength and fatigue properties of alloy 1575 of the Al – Mg – Sc system are studied after hot deformation (at 360°C) and subsequent cold rolling with different reduction ratios. The effect of the deformed structure on the properties and mechanisms of fracture of the alloy under cyclic tests is determined.

Weakening rolling texture in a nanotwinned copper

A randomly oriented copper embedded with nanotwin bundles was prepared by means of dynamic plastic deformation at cryogenic temperature. The subsequent cold rolling at room temperature induced shearing of nanotwin bundles, and resulted in a lamella structure after 90% thickness reduction. The volume fraction of copper-type rolling texture of the rolled nanotwinned copper is about 24.9±4.9vol%, much less than the rolled coarse-grained (~76vol%) and ultrafine grained ones. Detailed microstructure and texture characterizations show that the weaker texture is attributed to the evolution of nanotwin bundles retarding the formation of texture during cold rolling.

Bulk storage of “Wonderful” pomegranate fruit using modified atmosphere bags

“Wonderful” pomegranates can be stored under modified atmosphere (MA) conditions for up to 3–4 months after harvest. Until recently, the harvested fruit first needed to be transferred to the packing house and packed in MA bags in cartons or plastic boxes before cooling to the desired temperature and subsequent cold storage. During the last few years, together with StePac Ltd, we have developed a new methodology in which “Wonderful” pomegranate fruit are directly harvested into large 80 kg or even 320 kg bulk Xtend® MA bags in harvest bins, and then immediately transferred from the field to commercial cold storage rooms without the necessity of repacking the fruit at the packing house. In this study, we evaluated the postharvest storage performance and fruit quality of “Wonderful” pomegranates stored in bulk 80 kg Xtend® MA bags in harvest bins for various periods of 4, 8, 12, and 16 weeks at 7 °C followed by 1 week in shelf life conditions at 20 °C. The results show that “Wonderful” pomegranates can be maintained in bulk Xtend® MA bags in harvest bins at excellent quality with minimal losses for at least 12 weeks after harvest. Overall, this new suggested procedure allows direct transfer of large volumes of fruit from the field to cold storage rooms without intermediate transferring to the packing house, thus saving precious time and extra packaging and labor costs, and ensuring better maintenance of the cold storage chain.

Production, structure, texture, and mechanical properties of severely deformed magnesium

Methods of the severe plastic deformation (SPD) of pure magnesium at room temperature, namely, transverse extrusion and hydroextrusion in a self-destroyed shell, have been developed. The maximum true strain of the samples after the hydroextrusion was e ~ 3.2; in the course of transverse extrusion and subsequent cold rolling, a true strain of e ~ 6.0 was achieved. The structure and mechanical properties of the magnesium samples have been studied in different structural states. It has been shown that the SPD led to a decrease in the grain size d to ~2 μm; the relative elongation at fracture δ increased to ~20%. No active twinning has been revealed. The reasons for the high plasticity of magnesium after SPD according to the deformation modes suggested are discussed from the viewpoint of the hierarchy of the observed structural states.

Carbon sources and trophic relationships of ice seals during recent environmental shifts in the Bering Sea.

Dramatic multiyear fluctuations in water temperature and seasonal sea ice extent and duration across the Bering-Chukchi continental shelf have occurred in this century, raising a pressing ecological question: Do such environmental changes alter marine production processes linking primary producers to upper trophic-level predators? We examined this question by comparing the blubber fatty acid (FA) composition and stable carbon isotope ratios of individual FA (δ¹³CFA) of adult ringed seals (Pusa hispida), bearded seals (Erignathus barbatus), spotted seals (Phoca largha), and ribbon seals (Histriophoca fasciata), collectively known as "ice seals," sampled during an anomalously warm, low sea ice period in 2002-2005 in the Bering Sea and a subsequent cold, high sea ice period in 2007-2010. δ¹³C(FA) values, used to estimate the contribution to seals of carbon derived from sea ice algae (sympagic production) relative to that derived from water column phytoplankton (pelagic production), indicated that during the cold period, sympagic production accounted for 62-80% of the FA in the blubber of bearded seals, 51-62% in spotted seals, and 21-60% in ringed seals. Moreover, the δ¹³CFA values of bearded seals indicated a greater incorporation of sympagic FAs during the cold period than the warm period. This result provides the first empirical evidence of an ecosystem-scale effect of a putative change in sympagic production in the Western Arctic. The FA composition of ice seals showed clear evidence of resource partitioning among ringed, bearded, and spotted seals, and little niche separation between spotted and ribbon seals, which is consistent with previous studies. Despite interannual variability, the FA composition of ringed and bearded seals showed little evidence of differences in diet between the warm and cold periods. The findings that sympagic production contributes significantly to food webs supporting ice seals, and that the contribution apparently is less in warm years with low sea ice, raise an important concern: Will the projected warming and continuing loss of seasonal sea ice in the Arctic, and the associated decline of organic matter input from sympagic production, be compensated for by pelagic production to satisfy both pelagic and benthic carbon and energy needs?

Effect of hot rolling on the structure and the mechanical properties of nitrogen-bearing austenitic–martensitic 14Kh15AN4M steel

The effect of the rolling temperature and strain on the structure and the properties of corrosionresistant austenitic–martensitic 14Kh15AN4M steel is studied. The steel is shown to exhibit high ductility: upon rolling in the temperature range 700–1100°C at a reduction per pass up to 80%, wedge steel specimens are uniformly deformed along and across the rolling direction without cracking and other surface defects. Subsequent cold treatment and low-temperature tempering ensure a high hardness of the steel (50–56 HRC). Austenite mainly contributes to the hardening upon rolling in the temperature range 700–800°C at a reduction of 50–70%, and martensite makes the main contribution at higher temperatures and lower strains. Texture does not form under the chosen deformation conditions, which indicates dynamic recrystallization with the nucleation and growth of grains having no preferential orientation.

Microstructural evolution in Al–Mg–Sc–Zr alloy during severe plastic deformation and annealing

Annealing behavior of Al–Mg–Sc–Zr alloy processed by equal-channel angular pressing (ECAP) at 325 °C to various strains and undergone subsequent cold rolling to ∼80% reduction was investigated. ECAP to strain, e ∼3 formed partially recrystallized structure with ultrafine-grain (UFG) mantle zone along the boundaries of initial grains of ∼25 μm size in as-cast and homogenized condition, whilst ECAP to e ∼8 and 10 resulted in nearly 1 μm grain size, with their volume fractions being 0.7 and 0.9, respectively. These structures after ECAP exhibited sufficient stability, within normal grain growth up to ∼5 μm grain size only during annealing for 1 h in the temperature range of 350–520 °C. However, subsequent to ECAP cold rolling and further annealing at 425 °C and above revealed a distinct effect of prior ECAP. While the materials undergone ECAP to e ∼3 and e ∼8 and having lower UFG fractions revealed quite similar behavior, the material undergone ECAP to e ∼10 (and nearly complete recrystallization at ECAP) exhibited abnormal grain growth. The sources of microstructure evolution at different stages of processing are analyzed along with their effects on hardness at ambient temperature.

Back to the Wall: Myths and Mistakes that Once Again Divide Europe

Europe is once again subject to an epidemic of wall and barrier building. The war in Ukraine is accompanied by the fortification of its border with Russia, while the Baltic republics are creating the foundations for what is an embryonic new ‘iron curtain’ dividing the Atlantic community from Eurasia. Elsewhere fences are being built to halt the flow of refugees and migrants. These new barriers symbolize the failure to build a Europe ‘whole and free’ in the post-Cold War era, and the failure of the era of globalization to create the conditions for security and development in Europe’s neighborhood. The spate of ‘walling’ reflects not the strength of national sovereignty but its weakness, and not the power of the Atlantic community to spread prosperity, peace and security but the opposite. The era of globalization is accompanied by deepening disjuncture and contradictions, and European leaders have no coherent response. The roots of the crisis lie in the patterns established at the close of the original Cold War in the late perestroika years, with a power shift rather than the transcending politics espoused by Mikhail Gorbachev. The Malta summit of 1989 only partially repudiated the politics of Yalta. The asymmetrical end of the Cold War and the 25 years’ crisis represented by the subsequent cold peace contained within itself the violence and the new divisions that now predominate. The myths and mistakes of the cold peace era need to be challenged and a new transformative politics envisaged.

Superplasticity in a 5024 Aluminium Alloy Subjected to ECAP and Subsequent Cold Rolling

The superplastic behavior of an 5024 alloy, subjected to equal-channel angular pressing (ECAP) followed by extensive cold rolling (CR), was studied in the temperature range 250-500°C and at strain rates ranging from 10–4 to 10–1 s–1. The maximum elongation-to failure of ~1440% with a corresponding strain rate sensitive coefficient m of ~0.42 was attained at 450°C and a strain rate of ~1.4×10–1 s–1. The relationship between superplastic properties and microstructure of the alloy was discussed.

Novel Fabrication of Bulk Fine‐Grained Al–Cu–Mg Alloy with Superior Mechanical Properties

Bulk fine‐grained 2024 Al alloy is prepared by spark plasma sintering and subsequent thermal–mechanical treatment. Bulk sample with mean grain size of 2.68 μm is firstly sintered using gas‐atomized 2024 Al alloy powder. After subsequent solid solution, cold rolling and aging processing, bulk fine‐grained 2024 Al alloy with simultaneously enhanced strength and ductility is obtained. Specifically, the tensile strength and total tensile elongation of the peak‐aged sample are 583 MPa and 16%, respectively. The enhanced strength is mainly attributed to the refined grain size and the high number density of nano‐precipitates. The enhanced ductility is attributed to the regained work‐hardening capability by aging.

Tripling hardness of gold by micro alloying coupled with cold processing

Gold has broad applications in jewelry, but suffers from low hardness. In the present work, we show that simultaneous addition of 0.1 wt.% Ce and Si can nearly double the hardness of fine gold. We further show that hardness can be tripled by subsequent cold processing. By systematic structural characterizations and thermal analysis, we find that Ce and Si tend to segregate to grain boundaries and impede grain growth. Our work is helpful for development of new gold micro alloys and for design of jewelry that is more wear and scratch resistant.

Improved cold rolling workability of warm rolled Fe-6.5wt%Si electrical steel with columnar grains by annealing

The effects of annealing temperature (with the annealing time being constant at 1 h) on the microstructure, ordering, residual stress, mechanical properties, and subsequent cold rolling workability of Fe-6.5wt%Si electrical steel with columnar grains were investigated, where the steel was warm rolled at 500°C with a reduction of 95%. The results show that recrystallization began to occur in the sample annealed at 575°C and that full recrystallization occurred in the sample annealed at 625°C. When the annealing temperature was 500°C or greater, the extent of reordering in the sample was high, which reduced the room-temperature plasticity. However, annealing at temperatures below 300°C did not significantly reduce the residual tensile stress on the edge of the warm rolled samples. Considering the comprehensive effects of annealing temperature on the recrystallization, reordering, residual stress, and mechanical properties of the warm rolled Fe-6.5wt%Si electrical steel with columnar grains, the appropriate annealing temperature range is 300°C-400°C. Unlike the serious edge cracks that appeared in the sample after direct cold rolling, the annealed samples could be cold rolled to a total reduction of more than 71.4% without the formation of obvious edge cracks, and bright-surface Fe-6.5wt%Si electrical steel strips with a thickness less than 0.1 mm could be fabricated by cold rolling.

Microstructure and Superplasticity of an Al-Mg-Sc-Zr Alloy Processed by ECAP and Subsequent Cold Rolling

The feasibility has been demonstrated for achieving high-strain-rate superplasticity with elongations beyond 2000% in Al-Mg-Sc-Zr alloy with the partially recrystallized structure, produced by warm equal-channel angular pressing to strain of e~3 only. Subsequent alloy ambient temperature rolling up to e~1.6 enhanced the superplastic elongations and moved the optimum of superplasticity toward the higher strain rates.

Study of the laws of texture formation in the alloy 8011 during cold rolling and annealing

The texture evolution in grade-8011 aluminum alloy has been investigated during cold rolling and intermediate annealing. The main textural components of a hot-rolled blank have been determined using X-ray diffraction analysis and their evolution during subsequent cold rolling and intermediate annealing has been studied. The effects of the textural components on the dimensions and the arrangement of ears have been estimated at every step of producing a cold-rolled strip.

Survival of Queensland fruit fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) in apples treated with essential oils and cold storage

Little is known on the fumigant effects of essential oils on the immature stages of fruit flies (eggs and larvae). The present study aimed to investigate effects of fumigation with essential oil alone or followed by cold storage on the survival of Queensland fruit fly Bactrocera tryoni in Gala apples. Efficacy was based on the number of pupae recovered from treated and untreated fruits and on phytotoxic effects. In a 24h fruit fumigation test, peppermint oil applied at 100 and 200μL/L air was found to be active against B. tryoni eggs, whereas broad-leaved peppermint oil was active against both eggs and larvae but only at the highest dose tested (200μL/L air). However, both peppermint and broad-leaved peppermint oils sometimes had a phytotoxic effect on the apples. In a 6h fruit fumigation test, an equal mixture of peppermint and broad-leaved peppermint oil (100μL/L air) did not cause phytotoxic effect but had only a slight effect on B. tryoni eggs and no effect on the larvae. There was no synergism or additive effect when this essential oil mixture was applied in combination with subsequent cold storage. These results indicate that peppermint oil and broad-leaved peppermint oil have little potency for Gala apple fumigation since they were only effective at doses and durations of exposure which were phytotoxic to fruit. On the other hand, cold storage (4±1°C) alone was confirmed to be a very effective treatment against B. tryoni larvae and eggs in Gala apple without causing fruit damage and was not enhanced by prior fumigation with these oils.

Orizzonti di gloria e il canone del cinema bellico (1957)

Stanley Kubrick’s Paths of Glory (1957) is the first relevant American film on World War I after Howard Hawks’ Sergeant York (1941). Inevitably, World War Two, and the subsequent Cold War (with its hot moment in Korea), totally re-orienteered the movie genre, that in the thirties had flourished mainly on the memory - mediated by the war books boom of the late twenties - of the Great War. When he chooses to go back to the 1914-18 conflict, Kubrick deliberately goes back to the pre-World War Two canon, epitomized by Lewis Milestone’s All Quiet on the Western Front (1930). But at the same time, Paths of Glory represents the beginning of a new canon. Telling the story of a grotesque court-martial trial in a first line French infantry division, Kubrick depicts the Great War as the quintessence of every possible mass mechanized conflict, posing the founding stones of a canon which is still productive today.

Effect of annealing on the microstructures and properties of cold drawn Mg alloy wires

To prepare the biodegradable Mg alloy fine wires for the development of new biomedical Mg alloy implant devices, we investigated the static recrystallization behaviors of three kinds of Mg-rear earth (Gd, Y and Nd)-Zn alloys after intense cold drawing plastic deformation. The results demonstrate that all experimental alloys had good cold drawing formability, and showed similar static recrystallization kinetics with a recrystallization beginning temperature of ~300–350°C, a complete recrystallization temperature of ~400–425°C and a normal grain growth temperature ~450°C. Additionally, the grain morphology and texture play important role in affecting the subsequent cold drawing performance: more uniform and regular recrystallized grains are helpful to improve the subsequent cold drawing performance, but intense cold-drawn deformation texture which was hardly modified by heat treatment is harmful to subsequent drawing processing.