Strip Casting Research Articles

Application Analysis of Post Cast Strip Construction Technology in Building Construction

Application Analysis of Post Cast Strip Construction Technology in Building Construction

How the Other Half Laughs: The Comic Sensibility in American Culture, 1895-1920

How the Other Half Laughs: The Comic Sensibility in American Culture, 1895-1920

How the Other Half Laughs: The Comic Sensibility in American Culture, 1895-1920

How the Other Half Laughs: The Comic Sensibility in American Culture, 1895-1920

Cu-based amorphous alloy plates fabricated via twin-roll strip casting

Cu-based amorphous alloy plates with good mechanical properties have tremendous potential applications as structural materials. However, there is a lack of effective methods for preparing such plates. In this work, 0.53-mm-thick Cu47Zr45Al8 (at.%) and 0.25-mm-thick Cu64Zr36 (at.%) amorphous-alloy plates were prepared continuously by twin-roll strip casting, and their mechanical properties were investigated through both experiments and in-situ observations. The Cu-based amorphous-alloy plates prepared by strip casting were found to have good surface quality and shape; these plates did not exhibit tensile plasticity, but showed excellent bending and compression plasticity at room temperature. Such plasticity is achieved through the formation and evolution of multiple shear bands. Overall, the present study proves the feasibility of continuous preparation of amorphous Cu-based alloy plates with good plasticity by twin-roll strip casting and serves as a guide for this process in the future.

Twin Roll Casting and Secondary Cooling of 6.0 wt.% Silicon Steel

Iron–silicon alloys with up to 6.5 wt.% Si offer an improvement of soft magnetic properties in electrical steels compared to conventional electrical steel grades. However, steels with high Si contents are very brittle and cannot be produced by cold rolling. In addition to solid solution hardening, it is assumed that the B2- and DO3-superlattice structures are responsible for the poor cold workability. In this work, two cast strips with 6.0 wt.% Si were successfully produced by the twin roll strip casting process and cooled differently by secondary cooling. The aim of the different cooling strategies was to suppress the formation of the embrittling superlattice structures and thus enable further processing by cold rolling. A comprehensive material characterization allows for the understanding of the influence of casting parameters and cooling strategies on segregation, microstructure and superlattice structure. The results show that both cooling strategies are not sufficient to prevent the formation of B2- and DO3-structures. Although the dark field images show a condition which is far from equilibrium, the achieved condition is not sufficient to ensure cold processing of the material.

Simulation of Subrapid Solidification and Secondary Cooling for the Strip Casting of IF Steel.

A combination of droplet solidification tester and confocal laser scanning microscope was used to simulate subrapid solidification and secondary cooling process pertinent to the strip casting. The IF steel droplet had a delamination structure and the bottom part went through sub-rapid solidification. During secondary cooling, γ/α transformation mechanism belonged to interface-controlled massive transformation and the ferrite grains grew quickly. With the increase of cooling rate, the γ/α transformation temperature decreased and the incubation period and phase transformation duration reduced. The hardness showed a slight increase due to fine-grain strengthening. With coiling temperature increasing from 600 °C to 800 °C, the grain size became larger, precipitates became coarse, and defects in grain were recovered. Consequently, the hardness decreased.

Upscaling the 2‐Powder Method for the Manufacturing of Heavy Rare‐Earth‐Lean Sintered didymium‐Based Magnets

The 2‐powder method (2PM) is compared with the grain boundary diffusion process (GBDP) for the production of high coercivity didymium‐based permanent magnets with low amount of heavy rare‐earth (HRE). The advantage of using 2PM for large magnets is demonstrated. A coarse HRE‐free main phase powder (D50 = 5.5 μm) and a fine, HRE containing anisotropy powder (D50 = 2.1 μm), are produced by strip casting, hydrogen decrepitation, and target milling, with all processing steps in the 20 kg range. The powders are subsequently blended in different concentrations to reach a HRE content of 0, 1, 2, and 3 wt% in the sintered magnets. While remanence is only slightly reduced by this process, compared with the plain didymium magnet, the coercivity of the magnets is increased by up to over 750–1687 kA m−1. The microstructural and magnetic characterization both confirm the formation of a HRE‐enriched shell region enclosing the Nd2Fe14B grains. In contrast to magnets produced by GBDP, the amount of Dy substitution and thickness of the shells is constant throughout the entire volume of the magnet.

Evolution of solidification structure for Si–Mn bearing AHSS under typical cooling rates

In this paper, two near-net-shape continuous casting technologies (strip casting and compact strip production) were used to produce a typical Si–Mn bearing Advanced High Strength Steel (AHSS) slab/strip, aiming to provide a clear understanding on the cooling rate on the solidification structure and corresponding properties. The results showed that strip casting (SC) technology under sub-rapid cooling conditions owns a higher heat transfer efficiency, and the solidified grains have been obviously uniformed and refined. Meanwhile, a substituted quenching process has been completed under high cooling strength of SC, leading the structural transformation from the initial ferrite/pearlite to the composite structure of martensite and bainite, which provides a very good structural basis for the excellent comprehensive mechanical performance of Si–Mn AHSS.

Effect of cold rolling on microstructure and texture evolution in strip casting Fe-36%Ni invar alloy foil

A new processing route including strip casting, cold rolling and annealing was proposed to manufacture the 0.05 mm-thick Fe-36%Ni invar alloy foil. The as-cast strip had coarse columnar austenite grains and pronounced {100}<0vw>fiber texture due to the high melt superheat during strip casting. The severe cold rolling in one-stage cold rolling route led to inhomogeneous deformed microstructures and strong copper-type textures. The striking features were the absence of Cube texture ({001}<100>) in the 0.05 mm-thick cold rolled strip and the appearance of {001}<310>texture after annealing, differing from the results that sharp Cube texture was normally the unique annealing texture in case of severe cold rolling. By contrast, two-stage cold rolling route led to the sharp Cube texture after final annealing even the cold rolling reduction was as high as 92.9%. The different microstructures prior to final cold rolling may be responsible for the evolution of Cube and {001}<310>texture in various routes.

Effects of Nozzle and Roll on Surface Condition of Al-1%Si Strip Cast Using Vertical type High Speed Twin Roll Caster

When a strip of Al-Si alloy with an Si content of 1% was cast using a vertical-type high-speed twin-roll caster, cracks form in its surface. The effects of the pouring method, the shape and position of the nozzle, and the roll surface texture on surface crack formation were evaluated with a roll caster. The rolls were made of a copper alloy, and the roll speed was 30 m/min. The as-cast strips were bent to investigate the degree of crack formation, and the outer surface of the strips was observed without magnification and with a stereomicroscope to determine the influence of the pouring method, the shape and position of the nozzle, and the roll surface. A roll machined to form V-shaped grooves 0.4 mm deep on the surface of the strips was most useful for reducing surface cracking. Changing the shape of the nozzle tip was second-most effective. There was a clear correlation between the roll surface condition and surface cracking in the Al-Si strip.

Simulation of the Refining Process of Ultra-Low Carbon (ULC) Steel

The standard production route for mild steels for automotive purposes is still based on conventional continuous casting (CC) and hot strip rolling (HSR). The current trend towards the “zero-carbon car” will demand the abating of material emissions in the future. Thin slab casting and direct rolling (e.g., Arvedi endless strip production (ESP)) is an approach to reduce CO2 emissions by 50% compared to CC and HSR. One of the main limitations in applying ESP for the production of ultra-low carbon/interstitial free (ULC/IF) steels is clogging. Clogging is the blockage of the submerged entry nozzle due to the build-up of oxide layers or an oxide network. The high clogging sensitivity of IF steels results most probably from the FeTi addition, and hence, a general change of the deoxidation practice might be an option to overcome these problems. In the present work, the thorough refining process of ULC steel was simulated by addressing the different deoxidation routes and the influence of titanium (Ti) alloying on steel cleanness. The developed ladle furnace (LF) and the Ruhrstahl Heraeus (RH) refining models were applied to perform the simulation. Before the simulations, the models are briefly described and validated by the published industrial data.

Application of Post Cast Strip Construction Technology in Construction Process

Application of Post Cast Strip Construction Technology in Construction Process

Characterization of AA6111 aluminum alloy thin strips produced via the horizontal single belt casting process

ABSTRACT In this research, AA6111 aluminum alloy strips, 250 mm wide and ~6 mm thick, were produced via the horizontal single belt casting process. The strip microstructure was analyzed using optical and scanning electron microscopy, and the measured average grain size was 90 μm. This is significantly smaller than the average grain size of the products produced via direct chill (DC) casting route (i.e., 231 μm). An analysis of intermetallic compounds was also conducted using energy dispersive spectroscopy. These were observed to be distributed within and along the grain boundaries and are enriched in Mg, Si, and Cu. The shear punch test was performed to determine the ultimate tensile strength of the cast strip, which was observed to be 280 MPa. This value is significantly higher than the strength documented in the literature for DC cast products. A 3D profilometer was used to determine the top and bottom surface roughness of the as-cast AA6111 strips. The strip top surface was found to lie within 120 μm range, whilst the bottom surface roughness was less than 30 μm.

Improved cryogenic properties of the Al-xMg alloys enabled by twin-roll strip casting

Abstract High strength and ductility are vital material properties required in alloys used for structural applications at cryogenic temperatures. However, the simultaneous provision of these characteristics is challenging because the two properties are mutually contrasting from the perspective of dislocation motion. Herein, we prepare binary Al-xMg alloys supersaturated with Mg using a combined technique of twin-roll strip casting and subsequent thermo-mechanical treatment; this produces Al alloys with both high strength and ductility at cryogenic temperatures. Experiments show that gradually adding Mg to Al significantly improves cryogenic tensile properties of the alloys. At the cryogenic temperature of the liquid N2 (−196 °C), the Al-5Mg and Al-7Mg alloys exhibit the ultimate tensile strength (UTS) of 370 and 450 MPa with the corresponding ductility of 93% and 87%, respectively. Comparing Al-xMg alloys with differing Mg contents elucidates avenues of simultaneously improving these properties for utilization at cryogenic temperature. This study provides a simple and robust approach for producing low-cost Al-xMg alloys with excellent cryogenic properties for structural applications.

Applying crystallographic orientation analysis for exploring deformation mechanism of 6.5 wt.% Si electrical strip during twin-roll thin strip casting process

The study described here is aimed at illuminating deformation mechanism involved in Twin-roll Thin Strip Casting Process (TRSC) with respect to high-permeability 6.5 wt.% Si electrical strip (6.5 wt.% Si strip) in terms of crystal plasticity (CP) theory, and a Visco-plastic Self-consistent model (VPSC) was utilized to explore the deformation mechanism by applying crystallographic orientation (OR) analysis. Results underscore that the activation of overall potential single slip system with regard to studied 6.5 wt.% Si strip including { 110 } < 111 > , { 112 } < 111 > as well as { 123 } < 111 > can contribute to the OR conversion from Cube texture to Rotated-Cube texture, α-fiber texture as well as γ-fiber texture, while with different evolution rate during deformation. The potential multi-slip system of { 112 } < 111 > + { 123 } < 111 > with average number of activated slip system per grain ~9.1–9.4, and multi-slip system of { 110 } < 111 > + { 112 } < 111 > + { 123 } < 111 > with average number of activated slip system per grain ~10.4–10.8 are identified to be the predominant slip systems during deformation by comparing to the actual OR features obtained from TRSC-processed 6.5 wt.% Si strip. The CP-based method proposed in present study is deemed as a reference to investigate deformation behavior involved in the other semi-solid forming process.

Effect of Sub-rapid Solidification and Secondary Cooling on Microstructure and Properties of Strip Cast Low-Carbon Bainitic–Martensitic Steel

Effect of Sub-rapid Solidification and Secondary Cooling on Microstructure and Properties of Strip Cast Low-Carbon Bainitic–Martensitic Steel

Microstructure and magnetic properties of ultra-thin grain-oriented silicon steel: Conventional process versus strip casting

Ultra-thin grain-oriented silicon steels were processed via the conventional process and strip casting process, and the mechanisms of texture inheritance and inhibitor induced secondary recrystallization were comparatively studied in detail. In the conventional route with commercial grain-oriented silicon steel as the starting material, exact {111} 〈112〉 dominated the deformation texture after cold rolling with ~ 63% reduction, and strong Goss texture was formed in 0.08–0.10 mm thin-gauge primary recrystallized sheet. Meanwhile, weak {210} 〈001〉 and {h11} < 1/h12 > textures were also observed because of the inhomogeneous deformation with initial deviated Goss texture. After high temperature annealing, the sheet experienced incomplete secondary recrystallization with abnormal growth of Goss grains accompanied by normal growth of {210} 〈001〉 and {411} 〈148〉 grains, considering the absence of pinning force on grain boundary migration. In the strip casting process, the intensity of γ-fiber texture was increased, while grain size decreased from ~ 13.3 to ~11.4 μm and the area fraction of Goss grains decreased from 2.8% to 0.6% in the primary recrystallized sheet with decrease of thickness from 0.15 to 0.08 mm. During high temperature annealing process, MnS, (Nb,V)N and AlN provided continuous and sufficient inhibition force for normal grain growth, which guaranteed the formation of complete secondary recrystallization of exact Goss grains. Superior magnetic induction B8 was up to 1.97 T in the strip casting process, which was 0.09 T higher than the conventional route. Meanwhile, the iron losses P1.7/50 and P1.0/1000 were as low as 0.85 and 20.7 W/kg, respectively, which were comparable to the reported ultra-thin grain-oriented silicon steels. The present study provided a novel method to produce high efficiency ultra-thin grain-oriented silicon steel, which may significantly contribute to energy saving in high-frequency electrical devices.

Twin Roll Caster for Clad Strip

Production of aluminum alloy clad strips requires many processes, and a reduction in the number of processes has long been demanded. A method to cast clad strips directly from molten metal using a twin roll caster with copper rolls is proposed in this work. Two types of twin roll casters were designed and tested. One was a vertical-type tandem twin roll caster and the other was a twin roll caster equipped with a scraper. The casting of the clad strips was conducted in an oxidizing atmosphere. The clad strips were cast at speeds higher than 15 m/min. This casting speed is much higher than that of conventional twin roll casters for aluminum alloys. The roll load was smaller than 0.2 kN/mm. This small roll load means that strips were not bonded by hot rolling. The clad strips had a clear interface between strips, and elements in each strip did not diffuse into other strips. The clad strips did not fracture at the interface in a tension shear test. This means that the clad strips were strongly bonded.

Improvement of texture and magnetic properties of strip-cast grain-oriented electrical steel by trace Bi addition

The improvement of recrystallization texture and magnetic properties in grain-oriented electrical steel with trace Bi addition processed by strip casting process was studied in this study. Low casting temperature and sufficient liquid steel flow during strip casting process enabled relatively homogeneous distribution of Bi in the as-cast strip, which accelerated the precipitation during solidification and cooling process. As a result, relatively high density of duplex MnS + AlN, MnS and AlN was formed at grain boundaries and inside grain. Due to the synergistic effect of continuous precipitation and fragmentation of coarse precipitates during cold rolling, the number density of precipitates was increased and mean size was decreased along the processing route. High density of precipitates is attributed to severe inhomogeneous plastic deformation, which promoted the formation of high density in-grain shear bands during cold rolling and recrystallization Goss texture during annealing. Homogeneous microstructure with average grain size of ~ 11.6 μm, strong Goss texture with intensity of 2.5 multiples of random distribution, fine precipitates with number density of ~ 1.9 × 109 /cm2 and mean size of ~ 49 nm were formed after primary recrystallization annealing. Furthermore, grain-oriented electrical steel with Bi addition experienced complete secondary recrystallization of exact Goss grains during high-temperature annealing, which is attributed to beneficial optimization of Goss texture and strong inhibition effect, and superior magnetic induction B8 of 1.91 T was obtained. It is expected that this study paves a new way for fabrication of high-performance grain-oriented electrical steel.

Microstructure evolution and coercivity mechanism of hydrogenation-disproportionation-desorption-recombination (HDDR) treated Nd-Fe-B strip cast alloys

In this paper, we systematically investigated the microstructure evolution and coercivity mechanism of hydrogenation-disproportionation-desorption-recombination (HDDR) treated Nd-Fe-B strip cast alloys by transmission electron microscopy (TEM) and three-dimensional atom probe (3DAP) analyses. The rod-like NdH2+x phases with diameters of 10–20 nm are embedded into α-Fe matrix, which hereditarily leads to textured grains in HDDR alloy. The migration of NdH2+x from Nd-rich region to α-Fe matrix during hydrogen absorption process contributes to the uniform redistribution of Nd-rich phases after HDDR treatment. The HDDR alloy with single domain grain sizes of 200–300 nm exhibits relatively low coercivity of 1.01 T that arises from pinning magnetic domain motion. The weak c-axis orientation of HDDR alloy results in a lower reverse magnetic field (coercivity) to reduce remanence to 0. Moreover, the direct contact of Nd2Fe14B grains and the high concentration of ferromagnetic elements (Fe content ≈ 66.06 at%, Co content ≈ 0.91 at%) in Nd-rich grain boundary layer lead to strong magnetostatic coupling effect among Nd2Fe14B grains. The nano-sized α-Fe inside Nd2Fe14B matrix makes the magnetization reversal easily and decreases the coercivity of HDDR alloy.