A Proposed Hybrid Laser Quenching Process, and Investigation of its Three-Dimensional Forming Error

In this research, we focus on heat treatment, specifically during the downsizing of production systems. We devise a method designed to remedy the problem of quenching for thin plates, by using a small semiconductor laser. In this report, we investigated a method to reduce the influence, deformation amount, and three–dimensional (3D) distortion error of residual stress that occurred when a laser test was performed on a metal test piece. Regarding the residual stress, the specimen was burned out by continuous scanning. Its residual stress showed a tendency to fade as the specimen was scanned at lower speeds. We found it was possible to reduce deformation by restraining the specimen with the jig, but that 3D strain error under this constrained state remained of the same order as it was in the unconstrained state. In addition, by restraining the test piece with a jig, it was possible to prevent reverse deformation (Buckling Mechanism).

Rapid Calculation of Trimming Line for Panel Flanging Forming

Calculating the trimming line is an important step for the panel flanging. In this paper, we use the one step inverse finite element method to calculate the trimming line for auto panels flanging, the finite element model of flanging forming is established and completed the iterative solution of the equation, using the reverse deformation method to establish the linear elastic balance equation to solve the iterative initial value, and thus get the trimming line accurately and rapidly. Through the calculation of the trimming line of some flange part verified the effectiveness of the algorithm.

Influence of Forming and Flattening on the Measured Tensile Properties of Linepipe

Steelmakers are producing plates or coils, which are subsequently formed into pipes. The mechanical properties are checked after steel and pipe production, and it is commonly observed that the tensile properties of pipes differ from the properties of plate or coil. The difference in tensile properties is attributed to the forming of the pipe and the subsequent flattening of a pipe section to make a flat tensile test sample. The reverse deformation during pipe forming and flattening is expected to cause a Bauschinger effect leading to a decrease of the yield stress of the pipe compared to the yield stress of the base material. First, a kinematics description of the pipe forming is presented. This kinematics description is important to know the deformation path followed by the material during pipe forming, flattening and tensile test. Once the deformation path is known, the stress state can be computed using constitutive laws. Three constitutive laws are presented here and their ability to describe the mechanical behaviour is further discussed. To determine the mechanical behaviour in reverse deformation paths, a specific experimental set-up has been developed to make reverse tests in tension and compression. Using this experimental facility, an X60 grade on coil has been characterized. Models parameters are fitted on the experimental data. Using these model parameters, a tensile test after forming and flattening is modelled. The simulation shows that a very accurate description of material behaviour is required to predict the final tensile properties.

Mid-Cretaceous ductile deformation on the Eastern Palmer Land Shear Zone, Antarctica, and implications for timing of Mesozoic terrane collision

Ar–Ar dating of high-strain ductile mylonites of the Eastern Palmer Land Shear Zone in the southern Antarctic Peninsula indicates that reverse movement on the shear zone occurred in late Early Cretaceous times (Albian), and not latest Jurassic times as previously supposed. The Eastern Palmer Land Shear Zone forms a major tectonic boundary, separating suspect arc terranes from rocks of Gondwana continental affinity. The dated mylonites are developed in Lower Jurassic plutonic rocks at Mount Sullivan, eastern Palmer Land, and form part of a zone of ductile reverse deformation up to 25 km wide. Biotite from a fine-grained mafic mylonite yields an Ar–Ar cooling age of 102.8±3.3 Ma. Movement of this age on the Eastern Palmer Land Shear Zone is coeval with circum-Pacific deformation, possibly related to a mantle superplume event, and provides support for allochthonous-terrane models for the Antarctic Peninsula with accretion in post-Early Cretaceous times.

Superplastic Dome Forming of Machined Sheets

An experimental work on the superplastic bulge forming of machined sheets is presented in this study. Unlike the previously employed incremental-iterative method, a reverse deformation model was used to estimate the initial thickness distribution of the machined sheets from which a constant final thickness can be obtained when the shape of the bulged sheet is hemisphere. The reverse deformation modci was obtained by modifying previously-known models, which were based on the axisymmetric membrane and the incremental strain theory.Bulge forming experiments were conducted on machined sheets of Al alloy, A5083, at about 530°C under constant pressure control mode. The result of this simulation to estimate the final constant thickness distribution agreed well with the experiment, and confirmed that the reverse deformation model can be successfully applied in optimizing the thickness distribution of the starting sheets in order to obtain the desired final thickness distribution of the free bulged hemispherical product.