Analytical and experimental investigation of deformation in constrained groove pressing process

Constrained groove pressing process is a severe plastic deformation method, which can improve the properties of a metal sheet. The purpose of this research is to investigate the effect of deformation behavior and effective strain on the constrained groove pressed sheet properties. For this aim, deformation procedure and effective strain were investigated based on analytical relations and deformation geometry. Formation in the constrained groove pressing process was divided into the bending, stretching, and pressing sections, and the respective contribution of each in the formation procedure was evaluated. Then, the effect of main sections on the formation force, mechanical properties, and microstructure of constrained groove pressed sheets was determined by an experimental study. According to the analytical results, about 41.4% of the formation procedure occurs in the pressing section, creating 70% more effective strain than stretching section. Thus, the pressing section has a significant effect on the properties of constrained groove pressed sheets. The pressing section, due to more effective strain than the stretching section, creates 36% more yield strength, 14.6% more surface hardness, 37.6% more homogeneity and 22.6% smaller grain size. But, compared to the stretching section, the pressing section reduces elongation about 42.8%. So, to produce sheets with high ultimate strength and good formability, using the constrained groove pressing process in the stretching section is more effective.

Regenerated silk matrix composite materials reinforced by silk fibres: Relationship between processing and mechanical properties

Silk is a biocompatible material with remarkable mechanical properties. A variety of composite materials using silk as a matrix or for reinforcement have been prepared for many biological applications. However, although a range of composites containing silk have been designed, the mechanical properties achieved for the regenerated silk (solubilisation + film/matrix or fibre production) remain relatively weak (strength: 30–50 MPa). In this study, by combining the high ultimate strength (up to 1 GPa) of natural silk fibres and the chemical properties of regenerated silk, we developed a composite based on silk alone. We investigated how to improve the tensile mechanical properties of silk matrices derived from Bombyx mori silkworms by film processing and by incorporating silk fibres, either natural or degummed, that is, without the sericin coating. The structure and orientation modifications of fibroin macromolecules within the matrix were monitored by Raman spectroscopy; unexpectedly it showed that the most amorphous fibroin matrix exhibits the best mechanical behaviour. The mechanical behaviour of regenerated silk-based materials is dependent upon the temperature of evaporation and the filtration of the solution. In summary, a biocompatible composite was obtained here with distinct mechanical properties (strength >100 MPa; Young's modulus ∼2.5 GPa) which can be optimised for focused applications with silk fibres (slow degradation, skeleton of the composite) and silk matrix (fibroin molecules accessible to chemical or biophysical modification).

Experimental Analysis of the Feasibility of Shaving Process Applied for High-Strength Steel Sheets

In recent years, the engineered materials were developed to improve their mechanical properties. A high-strength steel sheet is one of them, developed to serve the requirement of reducing weight of vehicles. Therefore, as a new material, many researches have been carried out to examine the use of sheet metal forming process applied for high-strength steel sheet. However, the feasibility of shaving process applied for it has not been investigated yet. In the present study, this feasibility was revealed by using experiments on two types of high-strength steel sheets: SAPH 440 and SPFH 590Y (JIS). The relationship between shaved surface feature and shearing clearance of high-strength steel sheets corresponded well with those of their conventional metal sheets. However, due to the high ultimate strength of these materials, it was revealed in this present study that there were not any suitable conditions of shaving process that could be applied to achieve the requirements of smooth cut surface overall material thickness.

The Effect of Mn and Si on the Properties of Advanced High Strength Steels Processed by Quenching and Partitioning

The concepts new types of materials are, for economic reasons, focused mainly on low alloyed steels with a good combination of strength and ductility. Suitable heat and thermo-mechanical treatments play an important role for the utilization of these materials. Different alloying strategies are used to influence phase transformations. The quenching and partitioning process (Q-P Process) is one of the heat treatment methods which can result in a high ultimate strength as well as a good ductility. However, these good properties can be obtained only if a sufficient amount of retained austenite is stabilized. The influence of different contents of manganese, silicon and chromium on microstructural development and mechanical properties were experimentally tested. Alloying elements were used to stabilize the retained austenite in the final microstructure and also to strengthen the solid solution. Ultimate strengths of over 2000MPa with ductility over 10% were reached after the optimization of the Q-P Process. The microstructures were analyzed using several microscopic methods; mechanical properties were determined by a tensile test and the volume fraction of the retained austenite was established by X-ray diffraction phase analysis.

The Experimental Study on Arc Sprayed Mouldmaking for Plastic Products

In this paper, Arc sprayed mold-making technology process were described systematically, and some technique difficult points of this project have been solved. ? 2mm wire Arc spraying system is first applied in mold-making technology in China. A water solution release agent has been chosen to meet the requires of practical mold-making technology . A proper formula of backup materials is chosen by testing compression strength of different formulas. This backup material has high ultimate strength of compression and thermal conductivity and can be applied in practical mold making technology process.

Alkali-Activated Fly Ash-Slag Cement Based Nuclear Waste Forms

ABSTRACTThis paper is based on the results of an in-progress research project on Alkali-Activated Cement System at MRL. The objective of this research is to establish the potential for large volume use of fly ash and slag as main components of the cement system. Alkali-activated Fly ash-slag Cement (AFC) was studied as a matrix for immobilization of nuclear waste. AFC is characterized by high early strength, high ultimate strength, low porosity, lower solubilities of the hydrates, and high resistance to chemical corrosion as well as to freezing and thawing. All these advanced properties are particularly favorable to the immobilization the nuclear wastes.

Gradation and shear characteristics of four cohesionless soils

Comparison of typical results from drained triaxial tests carried out at confining pressures of 50 and 350 p.s.i. (3.52 and 24.61 kg/cm2) on four cohesionless soils are presented.The effect of gradation at constant relative density is explored, and it is concluded that there is an optimum gradation in terms of both high ultimate strength and high mobilized strength. Uniform coarse gravel is shown to have poor mobilized strength, but at confining pressures high enough to cause particle crushing the improvement in gradation and packing leads to a high ultimate strength, although large axial strains are necessarily induced. The optimum gradation is shown to be close to Fuller's curve for maximum density. The effect of increasing the confining pressure from 50 to 350 p.s.i. (3.52 to 24.61 kg/cm2) leads to a decrease in [Formula: see text] peak of 6 to 10°, but modifications for dilatancy lead to [Formula: see text] parameters that are sensibly constant for any one material.