Papers by Keyword: High-Strength

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Authors: A.P. Newbery, Byung Ahn, P. Pao, S.R. Nutt, Enrique J. Lavernia
Abstract: Mechanical milling of Al alloy powder in liquid nitrogen leads to a large reduction in the scale of the microstructure and results in material with high thermal stability and strength. However, it is important to consolidate the powder and achieve bulk material with sufficient toughness and ductility for structural applications. In this investigation, hot isostatic pressing, followed by quasiisostatic forging and hot rolling, were performed to fabricate Al 5083 plate with a predominantly ultra-fine grained microstructure. Plate produced in this way possessed enhanced tensile strength and ductility, exceeding that of conventionally processed material.
Authors: Hideto Oyama, Soichiro Kojima, Kousuke Ono, Yoshimasa Ito
Authors: Simon P. Ringer, S.P. Swenser, Barry C. Muddle, Ian J. Polmear, Takeaki Sakurai
Authors: Wen Quan Cao, Cun Yu Wang, Jie Shi, Han Dong
Abstract: In this study Quenching and Partitioning (Q&P) as proposed by Speer was applied to improve the ductility of C-Mn high strength Low Alloy steel (HSLAs). Microstructural observations revealed a multiphase microstructure including first martensite, fresh martensite and retained austenite in the Q&P processed steel. During tensile process, the austenite volume fraction gradually decreased with strain increasing, suggesting the phase transformation induced plasticity for the Q&P processed steel. Ultrahigh strength about 1300-1800MPa and tensile elongation about 20% were obtained after Q&P processing at specific conditions, which is significant higher than that of ~10% of conventional martensitic steel. The the product of tensile strength to total elongation increased from 25 to 35GPa% with increasing carbon content in studied steel. This improved mechanical properties were related to the ductility contribution from TRIP effects of the retained austenite and strength contribution from the hard martensitic matrix. At last it was turned out that the Q&P process is a promising way to produce ultrahigh strength steel with relative high ductility under tailored heat treatment conditions for different micro-alloyed carbon steel.
Authors: Jiong Feng Liang, Ze Ping Yang, Zhi Ming Qiu
Abstract: The mechanical properties of high-strength reinforced concrete beams strengthened with FRP ( fiber reinforce polymer) are further investigated theoretically including it s failure mechanism and loadability,based on earlier theoretical works on RC beams. And the correlation equation of flexural capacity on the cross section of high-strength reinforced concrete beams strengthened with FRP is deduced according to different types of failure.The correlation equation is shown to be in good agreement with the experimental results, which can be referred to engineering application.
Authors: Yong Wang, Ling Ling Cao, Yi Min Wang
Abstract: A carbon foam with high strength and high thermal conductivity was prepared through the incorporation of nano-titanium particle into mesophase pitch precursor. Results show that titanium act as catalysts to accelerate the graphitization of carbon, promote more perfect and larger crystallites and enhance the conductive and mechanical properties. Test results reveal that titanium doped carbon foam (TDCF) has excellent compressive strength and high thermal conductivity, with highest values reaching 29.6 MPa and 117.8 Wm-1 K-1 for a titanium concentration of 12 wt% in the precursor materials. More compact struts and cell walls stacked by more uniform were observed by scanning electron microscope in carbon foam. Correlation between the content of dopant and the properties and microstructure of TDCF was discussed.
Authors: Su Tae Kang, Jung Jun Park, Gum Sung Ryu, Gyung Taek Koh, Sung Wook Kim
Abstract: Ultra High Strength Steel-Fiber Reinforced Concrete (UHS-SFRC) is characterized by very high compressive and tensile strength that is about 8 times of ordinary concrete, and high ductility owing to the addition of steel fibers. This paper investigates the relationship existing among the direct tensile strength, flexural tensile strength and splitting tensile strength of UHS-SFRC. Differently from ordinary concrete, it is found that the first cracking strengths in UHS-SFRC obtained through direct tensile test and splitting tensile test are similar, while the strength obtained from flexural tensile test is significantly larger than those from other tests. Based on the experimental results, relationships between the direct tensile strength and flexural tensile strength, between the first cracking strengths in direct tensile test and in flexural tensile test, and between the first cracking strength in direct tensile test and the flexural tensile strength are proposed.
Authors: T.D. Hung, D. Pernica, Dora Kroisová, Oleg Bortnovsky, Petr Louda, Vladka Rylichova
Abstract: Geopolymer matrice Composites are fabricated at room temperature or thermoset in a simple autoclave. After approximately four hours of curing, composite materials exhibit excellent properties. Finding applications of geopolymeric composites in all fields of industry are the hot topics. This paper covers: (i) mechanical properties of fibers: carbon, Saint-Gobain Cemfil/CFV alkali resistance glass (various types), ARG-NEC (Nippon electric Columbia) alkali resistance glass, E-glass for pultrusion, AR glass for pultrusion were evaluated in accordance with Japanese Industrial Standard (JIS R 7601). (ii) properties of geopolymeric matrices: geopolymeric matrices are fabricated from various types of geopolymeric resins that were made at Research Institute of Inorganic Chemistry, Inc., Czech Republic and testing for mechanical properties, and by SEM for structure characterization. (iii) fabrication procedures of geopolymer matrix composites with carbon and other fiber reinforcements. (iv) results of mechanical testing of geopolymer composites, SEM for adhesion between the matrix and reinforcement, and (v) Results and discussion.
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