Advanced Materials Research Vols. 602-604

Abstract: Nanotechnology is a multidisciplinary and comprehensive frontier field. With the coming of the nano era, nanotechnology will have far-reaching impact of human life. It will also offer opportunities for the application of nano-materials in the field of sports engineering which promotes the leap-development of sports. Today, the nanometer materials have been widely used in the construction of sports venues, sports equipment, sport apparels and sport biology project and so on, the relevant departments should attach great importance to the development and research of nanometer materials in sports engineering from the height of strategy, seizing the opportunity and promoting the fast, healthy development of sports.

Abstract: Mechanical stability of retained austenite and its effect on mechanical properties of high strength TRIP steel were studied by means of OM, SEM, TEM, XRD, and mechanical testing after various heat treatments. Results revealed that the film-type retained austenite located between bainite laths with high carbon content showed gradual martensitic transformation with strain, demonstrating a good TRIP effect. Samples annealed at 800°C and held at 420°C showed an optimum value of strength and ductility product up to 18381.2MPa%. Transformation kinetics of the retained austenite were evaluated through tensile tests and fitted by the function y=0.86-0.86×exp(-Ax). The fitting results were good.

Abstract: Influences of normalizing and tempering temperature on mechanical properties and microstructure of steel casting were investigated in this paper. The results showed that as the normalizing temperature increased, tensile strength increased, while tensile stretch increased slowly at first and decreased at last. Steel casting got best comprehensive mechanical properties after a 970°C normalizing treatment. Normalized at 970°C and tempered at the rage of 500 °C and 550°C, steel casting got best comprehensive mechanical properties. The relation between mechanical properties and temperature was gotten using Matlab Software. The microstructure was ferrite and pearlite after normalizing, and tempered sorbite after high tempering.

Abstract: This paper presents the microstructure, mechanical properties and carburized behavior of new type bainitic carburized steel. The results show that after new carburized steel is normalized at 920°C and tempered at 300°C, its microstructure consists of bainitic ferrite and residual austenite, and belongs to the carbide-free bainite or atypical bainite. Large or small cross-section size new carburized steel bar all have reached the performance requirements of Cr-Ni carbonized steel. The microstructure of new carburized steel surface consists of high carbon martensite and residual austenite after carburized and air-cooled, It retains austenite fraction of the new carburized steel and 18Cr2Ni4WA steel are about 18% and 38%, respectively. Carbon concentration gradient of new carburized steel changes smoothly and have ideal carbon concentration distribution. Effective carburizing surface depth of new carburized steel is about 0.6mm and is smaller than 18Cr2Ni4WA steel. The gear entities made of new carburized steel meet the technical requirements of heavy duty carburized gear.

Abstract: In order to research the cold deformation work hardening characteristic of new type low carbon bainitic steel, this article studies the effect of different degrees of cold deformation (elongation and compression) and different tempering temperatures on microstructure and mechanical properties of 15SiMn2Mo low carbon beinaitic steel. The results showed that with the tempering temperature increasing after 10% pre-tension deformation, the tensile strength and yield strength of the test material increased first and then decreased, and reached its peak value at 300°C, roughly the same as the strength of hot-rolling and 300°C tempering. With the compression deformation degree rising, the hardness of test material increased and showed the test material has good work hardening performance. Streamline and "z" shape ferrite banding appeared in microstructure. With the tempering temperature increasing, the microstructure of compressed deformation steel recoveried and recrystallized, the tendency of ferrite along the streamline was weakened, the new refining granular phase was enhanced and uniformity of microstructure was improved. The microstructure refinement was significantly increased with the compressive deformation degree rising.

Abstract: Study here focuses on the efficient utilization of the advantages of organic polymeric materials such as their low mass density and high tensile strength, etc, and at the same time avoiding their disadvantages like low/soft stiffness and rapid deterioration of mechanical properties in the aggressive or corrosive environment. To realize this aim, one methodology is adopted in this work by introducing the stainless steel thin film or sheet in the design to improve the anti-corrosion behaviors of the fabricated composite. Mechanical tests are also carried out to measure the effects of peeling rates on the nominal bonding strength which is a key parameter to characterize and evaluate the reliability of the whole designed structure under various loading conditions. In this way, the applications of composites made of mainly organic polymeric materials may be extended to larger engineering areas. The influence of peeling rate over the bonding strength is also discussed.

Abstract: The test of 20MnSiV Ⅲ grade reinforced bar is carried out at room temperature and other nine temperatures: 100°C、200°C、300°C、400°C、500°C、600°C、700°C、800°C、900°C.The results show that, the highest impact absorbing energy 137J appeared when the test temperature is 200°C, while the lowest is 75.5J when the temperature is 600°C. While the test temperature is over 700°C and the sample is near damaged, strain softening and serious longitudinal extension is happened in the course of impact, and the gap of the sample can not result in the concentration of stress-strain, fracture mechanism of the material is changed, and then impact absorbing energy had no practical significance.

Abstract: According to the typical large-diameter thick-walled steel T/P91 (10Cr9Mo1VNb), during the hot working, there are dynamic recrystallization and grain growth. The influence of the samples at different hot treatment on the grain size and grain growth rate were obtained by the statistics of the grain size, The grain growth index under various heat treatment were compared, the mathematical model of the austenite grain growth law of P91 alloy steel was established.

Abstract: The IGF refined microalloyed non-tempered steel with high strength and toughness is developed, by adding trace elements such as vanadium and titanium and using aluminum as the deoxidizing elements. The combination of these elements and elements C and N in the steel leads to the precipitation of a great deal of fine and scattered alloy carbides and nitrides. These fine particles provide ideal precipitation positions for IGF’s nucleation. The results show that a lot of IGF appears in the developed steel after hot-forging and air cooling, which effectively divides up the austenite grains and refines the steel structures. The strength and toughness of the steel is increased. The tensile strength reaches 1150Mpa and the impact toughness is between 61.35-65.37J/cm².

Abstract: The effect of intercritical quenching temperature on the microstructure and performance of a 650 MPa low-carbon structural steel was investigated by optical microscope and mechanical test. The results showed that the obtained microstructures at different temperature were mainly bainites, the volume fraction of the bainites was gradually increased and the size of which became finer with the increase of the quenching temperature. Moreover, as the temperature increased, the yield strength and tensile strength gradually increased; the yield ratio decreased initially and then increased; the impact energy increased among the temperature range of T3°C and T4°C, subsequently dropped significantly at T5°C, and then increased atT6°C. The best comprehensive performance was obtained at T4°C in this study.