Advanced Materials Research Vols. 690-693

Abstract: The texture of as-cast AZ80 magnesium alloy after multi-axial forging processes was investigated by electron backscatter diffraction (EBSD). The results show that, the first cycle induced two groups of texture forming, which had certain angles to the elongated direction and had high strength surface texture in specimen. However, after the second process, dynamic recrystallization occurred and majority of tensile twins developed, which made a small deflection on basal plane, and the orientation of the texture of basal plane changed. It resulted in the texture intensity decrease. The weak texture formed during multi-axial forging process is different from that formed during extrusion, rolling and other processes significantly.This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Abstract: The flow stress of a high-Mn austenitic Fe-20Mn-3Si-3Al TRIP steel was investigated by isothermal compression tests on Gleeble 3500D thermo-mechanical simulator in the temperature ranges from 900°C to 1100°C and the strain rate ranges from 0.01s-1 to 10s-1. The results show that the flow stress is sensitively dependent on deformation temperature and strain rate, and the flow stress increases with strain rate and decreases with deformation temperature. The flow stress during isothermal compression can be described by the Zener-Hollomon (Z) parameter in the hyperbolic sine equation with the hot deformation activation energy Q of 385.2kJ/mol.

Abstract: This paper focused on the piercing process in order to obtain the optimum mold parameters with the finite element method. In present investigation, the clearance, punch-die round radius and the interaction of between clearance and punch-die round radius were studied by simulating the piercing operation of a Q235 sheet. Simulation used the FEM program ANSYS. The results of the present paper showed that clearance was the most influential factor for piercing, and numerical experiments was an effectiveness method to get optimal parameters of mold parameters, and the numerical experiment results showed that the best clearance could be got.

Abstract: Tensile and impact toughness test on X100 line pipe with different pre-strain at different aging temperature were conducted to study the effect of pre-strain and aging temperature on properties of X100 line pipe. The result shows that yield strength and tensile strength of X100 line pipe would increase significantly with the introduction of pre-strain, while the impact toughness would decrease significantly. Effect of strain aging on tensile properties of X100 line pipe are more significantly. The yield strength, and tensile strength would increase significantly with the introduction of strain aging both transversal and longitudinal direction.

Abstract: Liquid forging is a new technology of plastic forming. It is a kind of bulk forming process with liquid metal with high-quality and efficiency and it has the characteristics of both die casting and forging. This paper will discuss the liquid forging process, die design, simulation and optimization of liquid forging [1].

Abstract: The main purpose of this work is to develop an intellectualized control technique on the deep drawing of rectangular pan made of AISI 304 DDQ stainless steel using genetic algorithm and finite element methods. These control methods are employed in order to investigate the most significant parameters in sheet metal forming process such as drawing force, with a view of optimizing these parameters. The genetic algorithm is used for the optimization purpose to minimize the force of the deep drawing process and to investigate the roles of other parameters. Experimental results show that these combinations of control system can cover a wide range of both materials and influential forming parameters automatically. The results further confirm that the developed system is effective and valid alternative for quick responsible control system with high flexibility.

Abstract: This paper presents the development of secondary controlled hydraulic pressure forming of sheet metal for both potential energy saving and electric motor power consumption reduction. Most of the reported existing pressure forming processes have limited pressure application and are mostly used for batch production. Above all, none of the existing processes use hydraulic accumulator and hydraulic transformer to save and reuse the energy or convert the system pressure and flow to the predetermined load requirement which could prevent wrinkling and fracture effect caused by low and unduly high pressure. Instead, most of the processes throttle excess fluid that is not required back to the reservoir thereby wasting excess motor energy as well as generating heat to the system. The resultant effect been the use of much energy during metal forming operation that leads to enormous financial lost to companies. It was as a result of these problems that the research was carried out. This development uses two secondary units (the hydraulic transformer) to transform a low pressure/high fluid flow into a high-pressure/low fluid flow. The use of variable speed drive (VSD) unit prevents pressure surges and ensures smooth starting and stopping of the machine. The hydraulic punch unit coupled to the hydraulic cylinder (ram) on a single action stroke performs the forming operation when the cylinder rams strikes. During ram retraction, the system saves and recycles both the hydraulic energy and generated heat back into the accumulator. The highly pressurized fluid generates a force of about (1500kN) which is used to power the punch piston for steel forming of thickness between 1.00mm-2.5mm. This operation leads to mass production of high strength, quality surface textured metallic parts within a second. The system simulation is performed using SIMULINK. The experimental results does not only agree with theoretical analysis but also appears to prove that the system is very efficient in energy saving and recuperation.

Abstract: The loading path is crucial to the quality of forming parts in the process of tube hydroforming. The counterpunch is usually used to control the protrusion height and also to control the evolution of thickness and avoid over thinning in T-shape hydroforming. In this study, the experiments of T-shape hydroforming are conducted, in which tubular material used is stainless steel and has an outer diameter of 103mm. A fuzzy logic-based load control algorithm is developed for optimizing the loading path, and four different initial positions of the counterpunch are designed to investigate its influence on wall-thinning and the corner radius at protrusion end. The results show that the minimum thinning can be obtained with an initial position of 12.5mm, while a smaller corner radius is obtained with an initial position of 37.5mm.

Abstract: The process parameters including the mandrel structure of radial-axial ring rolling is in close relationship with the forming defects such as over-high axial spread and the folding defect in the connecting part of the big and small ring. In this paper, a 3D rigid-plastic and coupled thermal-mechanical finite-element model (FEM) of radial-axial ring rolling for large-scale T-sectioned ring was developed using commercial software of DEFORM-3D. By changing the chamfer radius of mandrel's work roll, the effects of mandrel structure on the height of axial spread which considerably affects the stability of the ring rolling process were investigated. The folding defect was also simulated. The numerical simulation results showed that with the decrement of the chamfer radius r, the metal increasingly accumulated in the big ring and the axial spread height increased. Consequently, the ring rolling process became unstable. Also, the folding angle augmented.

Abstract: To obtain the effects of parameters on wall thinning ratio of 7075 cast aluminium alloy tube in one pass hot power backward spinning accurately, a method to accurately describe the wall thinning ratio of the spun tube has been proposed. Combined with the FE analysis, the change regularities of the wall thinning ratio with the variation of process parameters were obtained. The results show that wall thinning ratio increases gradually firstly, and then tends to a stable value with the increase of preheating temperature. With roller feed rate increasing, wall thinning ratio increases firstly, and then decreases. The wall thinning ratio increases gradually with the increase of roller fillets radius, but the trend becomes larger.