Advanced Materials Research Vols. 634-638

Abstract: Enterprises have been looking forward to breakthroughs of compound cold rolled section steel precise pass design algorithm for a long time; the breakthroughs will enlarge the application area of cold rolled steel. However, further study of stress and strain cannot effectively conduct pass design algorithm, the theory research and pass design have bottlenecks. Use spline finite strip method to guide pass design, with artificial intelligence correction, we can gen precise pass design method. These researches will offer theoretical foundation to precise pass design and pass software design.

Abstract: The formability of a TRIP590 steel with 0.67mm thick in incremental sheet forming (ISF) was investigated. A variable angle cone, which opening diameter and generatrix radius are 100mm, and initial angle is 35 °, was formed until the specimen cracked. The depth at the intersection point of the actual wall thickness and theoretical wall thickness of the cone was measured, and the forming limit angle of the TRIP590 steel was got and about 66.5 °. Additionally, an arc groove and a cross arc groove were formed. Through measuring changes of the grids printed on the surface of the tested sheet, the forming limit diagram of the TRIP590 steel in ISF was obtained. The forming limit angle and diagram obtained can be used in designing the production process and numerical simulation of forming the TRIP steel.

Abstract: Because of the unique advantages of indirect squeeze casting, has become a heated topic of current national research. Indirect squeeze casting research status and current problems are studied. Finally, come out the prospect for the future development.

Abstract: Zipper manufacturer always requires Y type zipper to design clothes. To meet the huge global demand, the high-precision forming process is required to improve production speed and production accuracy. The basic component of Y type zipper is the metal Y type teeth. The poor design of drawing process without optimization will result in bad quality of products. The most common defects of Y type teeth drawing process included (1) the teeth size error caused zipper sudden opening, two rows of Y type teeth cannot be close together; (2) zipper does not pull smoothly, it needs more pull force; (3) too much residual material cause higher cost and poor performance; (4) unstable quality cannot reach the standard of high level zipper. This article uses the finite element method to simulate the drawing process of copper Y type teeth. Computer-aided analysis software ABAQUS CAE is applied to execute drawing process simulation analysis and to obtain the optimal design parameters of drawing. Based on the best modeling of the FEM prediction, the complicated relationships between the experiment drawing Y-slot die parameters and the max. deformed can be obtained, the max. deformed error is 7%.

Abstract: The effect of forming parameters during the incremental sheet forming process (ISF) was studied for a circular shape sheet part. ISF is known as a rapid prototyping method to pro-duce sheet metal parts in a batch production series. ISF has found to be useful and advantageous which increases its application in industry. A CNC lathe machine was used in this study because it was easily programmed to move an indenter which worked as the tool, through the sheet metal which was clamped on a plain rounded mold. The work also investigated the influence of some process variables such as spindle speed, tool material; tool feed rate and temperature during the forming procedure. The results showed that a proper spindle speed and tool feed rate at some stage in the forming process improved the surface quality and the rate of penetration.

Abstract: Complex phase steel CP 800, a kind of advanced high strength steel (AHSS), exhibited quite high carbon equivalent (CE) which was a detrimental factor for weldability of steels. Thus the weldability of CP 800 steels containing (in wt%) 0.06C-0.45Si-1.71Mn-0.11Ti was extensively studied. Mechanical properties and impact toughness of butt joint, the welding crack susceptibility of weld and heat-affected-zone (HAZ) for tee joint, Control Thermal Severity (CTS) welded joint, and 60°Y-groove butt joint were inspected after gas shielded arc welding tests. The impact toughness was larger than 27J either at room temperature (RT) or at -20°C, indicating good impact toughness of the weld of the steel. In addition, welding crack susceptibility tests revealed that the weldments were free of surface crack and other imperfection, showed fairly good weldability. In application, the longitudinal control arm of automobile made of this steel exhibited excellent fatigue and durability performance.

Abstract: This article puts forward One-step forming simulation method to solve blank outline problems in the process of sheet metal forming. The blank outline curve is got from the simulated analysis of Groupware of Fender by one-step simulation in Dynaform 3D software for sheet forming, considering the final shape of the workpiece. It simulates three programs via three different shapes of blanks. And it compares and analyze the FLD diagram and forming results ,and then it gets the optimized blank shape. This way guides the mould design, and save the time of repairing moulds on the basis of producing qualified products. It overcomes the puzzle how to choose the blanks’ size and shape.

Abstract: The melting curves of high cesium content KF-CsF-AlF3 flux samples prepared by the wetting synthesis method were measured by differential scanning calorimetry (DSC), and the effect of the flux compositions on the melting characteristics was analyzed and summarized. Existing phases of every representation sample was identified by X-ray diffraction (XRD), meanwhile, the morphology and chemical elements of the typical flux samples were analyzed by scanning electron microscope (SEM) and energy spectrum analysis (EDS), respectively. The results indicated that solid phase decomposition first occurred in the common phase Cs2AlF5 for all the flux samples at 420°C; one of the decomposition products, Cs3AlF6 take the eutectic reaction with the Cs2KAlF6 at about 450°C; the flux samples containing phase CsAl2F7 or Cs2KAl3F12 have the e5 and e1 eutectic reaction at 471°C and 525°C, respectively, and their liquidus increased correspondingly. The liquidus for regionⅠflux samples is about 450°C and with a narrow melting range, which would make them good substrates for aluminum alloy middle temperature brazing.

Abstract: The CTOD (Crack Tip Opening Displacement) evaluation and control for HAZ (Heat Affected Zone) toughness of welded joints are the most effective measures to the security of steel structures. This paper address the problem of the newly developed offshore structure steel API 2W 50Z with heavy thickness of 100mm. In accordance with the American Petroleum Institute standard Recommended Practice 2Z (API PR 2Z), the CTOD tests of two critical positions of HAZ in three kinds of heat inputs were carried out in low temperature (-10°C). All of these CTOD testing and assessments are finished under the witness of American Bureau of Shipping (ABS). The result shows that all of the CTOD values are greater than the required value (0.38mm) in API RP 2Z. This indicates that the newly developed offshore structure steel (API 2W 50Z) meet the requirement of the toughness. Further, the CTOD testing and assessments in several international standards about weld joints of steel plates are also compared and discussed in this paper.

Abstract: The microvoids structure changes of the PAN fibers were characterized by synchrotron radiation SAXS. The synchrotron radiation SAXS patterns and the changes of scattering intensity show that after various fiber spinning process, microviods were gradually oriented in parallel with the fiber axis, and the number of the microvoids was decreased. Fankuchen tangent method was used to deal with the experimental data. After the first coagulation bath, a large number of microvoids were formed in fibers, the aspect ratio was close to 1.0, the shape was nearly spherical, and the radius of gyration (Rg) was 14nm. During plasticizing drawing and washing process, the dimension of microvoids was decreased. Rg was 10nm, the aspect ratio reached 1.6, the shape of the microvoids was nearly ellipsoidal, and the microvoids exhibited preferred orientation along the fiber axis direction. After the processes drying collapsing and drawing in vapor, the scattering intensity of fiber drastically decreased, the number of microvoids significantly reduced, Rg turned to 12.9nm, and the aspect ratio reached 1.9. During heat setting process, the aspect ratio of microvoids reduced, but Rg slightly increased.