Advanced Materials Research Vols. 1061-1062

Abstract: Cold rolled thin strip has received a great deal of attention through technological and theoretical progress in the rolling process, as well as from researchers who have focused on some essential parameters of strip such as its shape and profile. This paper describes the development of a 3-D finite element model of the shape of thin strip during cold rolling to simulate the cold rolling of WCS (work roll crossing and shifting) in asymmetric rolling. This finite element model considers the asymmetrical rolling parameters such as variations in the diameters of the rolls and the crossing angle as the work roll shifts on the strip during cold rolling. The shape and profile of the strip are discussed in the asymmetrical and symmetrical rolling conditions, while the total rolling force and distribution of stress are discussed in the case where the roll cross angle and axial shifting roll changes. The results can then be used to control the shape and profile of thin strip during rolling.

Abstract: This paper presents a sequential coupled thermo-metallurgical-mechanical finite element model for low alloy steel quenching which can be used to predict temperature history, evolution of microstructure, internal stress and distortion. The main efforts are to develop a series of subroutines which consider the latent heat released due to phase transformation and numerical implementation of a thermo-metallurgical-mechanical constitute equation. The effectiveness of developed computational method is confirmed by a immersion quenching. Simulations of immersion quenching demonstrate that transformation induce plasticity has significant effect of the evolution of residual stress, distortion and can not be neglected for low alloy steel during immersion quenching.

Abstract: B₄C/TiNi mixed powders with different composition (10B₄C+90TiNi and 20B₄C+80TiNi in wt. %) prepasted on Ti-6Al-4V substrates were scanned by a FL-Dlight02-3000W semiconductor laser to obtain TiB_x+TiC reinforced graded composite coatings. The influences of the processing parameters on the microstructure of the coatings were studied. Optimal processing parameters were obtained with laser power (P) 1700W/1900W, laser scanning speed (V) 6.67mm/s and defocus length 310mm. The microstructures and phases of the coatings were analyzed with OM, SEM and XRD respectively. Graded composite coatings with in-situ synthesis of TiC, TiB and TiB₂ reinforcements in the matrix of Ti₂Ni and TiNi were obtained.

Abstract: Expandable tubing technology got great development in the past few years because of its extensive usages. Expandable material must has such properties as lower yield strength, higher tensile strength, better plasticity and strain hardening properties, and so on. This paper introduced some expansion forming parameters. These expansion forming parameters can be used to characterize the expansion properties.

Abstract: Thermoplastic polyurethanes elastomer (TPU) was foamed during injection molding. The effects of processing parameters on tensile strength and weight reduction were analyzed using Orthogonal Experimental Design. The results show that the effects of shot size on the tensile strength and weight reduction are largest, and melt temperature is the key factor on the ratio tensile strength to weight.

Abstract: Cr/WC-Ni composite coating was prepared on Cr12MoV die steel by thermal spray technique, and then further treated using laser cladding technique. WC powders was coated Cr by D.C. magnetron sputtering method. The structure, composition, hardness, morphology were analyzed and measured by XRD and SEM and hardness tester. Tribological experiments were carried out on an abrasion machine. The results showed thatCr film prevented WC decomposition, and Cr/WC-Ni coating had the higher hardness values compared with WC-Ni coating. After the treatment with the laser cladding, the coating surface was uniform and compact and had no cracks, the boding between the matrix and coating surface had a good metallurgical bonding, and sub-surface showed a higher hardness.

Abstract: This paper aims to investigate orbital drilling process in carbon-fiber reinforced plastic (CFRP) composites with multi-point orbital drilling tool based on the robot automatic drilling system. One orthogonal experiment has been carried out, and the cutting forces of different parameters were measured online by dynamometer. Furthermore, the cutting force model was established through regression analysis, and the impacts of cutting parameters on thrust force were deeply analyzed. In addition, delamination and tear defects were inspected respectively, and the relationship between thrust force and delamination and tear was discussed. Our results indicate that thrust force increased with the increasing feed rate and axial feed depth, while decreased with the increasing spindle speed. Axial feed depth was found as the predominant factor on thrust force and defects. At last, the cutting parameters was optimized and then thrust force decreased more than 26% with almost none tear and burr around the hole, which indicates a better machine quality.

Abstract: The paper describes a vibrations acceleration signals scanning and processing principle at technology head characteristic frequency reading during AWJ manufacturing process.

Abstract: A simulation model established by finite element methods using ANSYS software shows the distribution temperature field on titanium surface during misting strengthening process. The actual strengthening experiment was conducted. The results show that the simulation calculation results are consistent with those of experiments under the same strengthening experimental conditions. The simulation model is benefit to strengthening quality forecast, parameter regulation and optimization in the EDM strengthening process.

Abstract: The influences of different voltage and mold temperature on solidified structure and mechanical properties of Mg₉₇Y₂Cu₁ alloy reinforced by long-period ordered structure under AC magnetic field were studied. The results show that grains of Mg₉₇Y₂Cu₁ alloy can be refined by AC magnetic field treatment. Macrostructure of the alloy is changed from coarsened grains to complete fine equiaxed grains. The initial dendrites are broken and and they have a tendency to break into several fragments. The second phase becomes more continuous and uniform, its volume fraction increases. When the voltage is at 0~250V, grain size of the alloy decreases firstly, then increases, and the turning point is 200V. When the mold temperature is at 20-600°C, grain size of the alloy increases grossly with the increase of the mold temperature. The change law of mechanical properties of the alloy is opposite to the change law of grain size. When the voltage is 200V, the tensile strength and elongation of the alloy are increased by up to 16% and 47%, respectively, compared with the alloy in traditional condition.