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Finite element analysis of material deformation behaviour during DRECE: the sheet metal SPD process

Tkocz Marek, Kowalczyk Karolina, Bulzak Tomasz, Jabłońska Magdalena B., Hawryluk Marek

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e145, 2023

EN

The material deformation behaviour during the innovative SPD process called DRECE (Dual Rolls Equal Channel Extrusion) has been analysed by FEM simulations. In the process, a workpiece in the form of a strip is subjected to plastic deformation by passing through the angular channel; however, the workpiece dimensions remain the same after a pass is finished. Performing consecutive passes allow for increasing the effective strain in the material to a required level. In the conducted simulations two various channel angles (108° and 113°) have been taken into consideration, as well as two processing routes, A and C (without and with turning the strip upside-down between consecutive passes, respectively). The analysis of simulation results has revealed that significant strain and stress inhomogeneities across the strip thickness are generated in a single DRECE pass. The die design (the inner and outer corner radius) and friction conditions affect the material flow, reducing significantly the shear strain in the near-surface regions of the strip. The strain inhomogeneity can be effectively reduced by choosing the processing route C. The strain distributions and the corresponding tensile test results have confirmed that the smaller channel die angle allows to generate larger strain and higher strength of the strip but also reduces its ductility more than the die setup with the larger channel die angle.

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Deformation behaviour of high-manganese steel with addition of niobium under quasi-static tensile loading

Jabłońska Magdalena Barbara, Jasiak Katarzyna, Kowalczyk Karolina, Bednarczyk Iwona, Skwarski Mateusz, Tkocz Marek, Gronostajski Zbigniew

Materials Science Poland

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2022

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Vol. 40, No. 3

1--11

EN

In this paper, the heat generated during deformation under the static testing of high-manganese TWIP steel with addition of niobium was determined. The research combined the interaction of heat generated during deformation, mechanical properties, hardness and microstructure. Temperature and strain were measured simultaneously using infrared (IR) thermography and digital image correlation (DIC) method. The average temperature measured at the necked region equals 42°C at the strain rate of 0.001 s−1 and exceeds 100°C at 0.5 s−1. Therefore at large strains, a reduction in stress was observed. The course of the hardness change coincides very well with the strain changes, however, at the strain rate of 0.5 s−1 near to the necking area the hardness equals to 360 HV2, whereas at the lower strain rates it equals to 370 HV2. These changes are connected mainly with increase in temperature to >100°C

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The influence of post-deformation annealing temperature on the mechanical properties of low-carbon ferritic steel deformed by the DRECE method

Kowalczyk Karolina

Materials Science Poland

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2021

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Vol. 39, No. 3

430--435

EN

The paper presents observations on the mechanical properties characterizing low-carbon steel subjected to deformation by the dual rolls equal channel extrusion (DRECE) method and annealed for 60 min in different temperature variants in the range of 450–700°C. The DRECE process was carried out up to seven passes at ambient temperature. The investigations carried out revealed that the strength of the steel strips increases corresponding to the rise in the number of DRECE passes applied. The yield strength (YS) after seven passes is >2.5 times higher compared to the material in the initial state (before the deformation process). However, the tensile ductility decreased significantly after the DRECE. In order to obtain favorable mechanical properties, the steel strips were subjected to annealing. Our study demonstrates that after being processed by the DRECE method, low-carbon steel can be subjected to low-temperature annealing to ensure that it is endowed with high strength, while maintaining the characteristic good ductility of the material. The results of the research were analyzed in the context of an investigation into the microstructure change, assessed by scanning transmission electron microscopy (STEM), induced in low-carbon steel subjected to the DRECE process and low-temperature annealing.