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dc.contributor.author
Peterli, Maurice
dc.contributor.supervisor
Hora, Pavel
dc.contributor.supervisor
Volk, W.
dc.date.accessioned
2017-10-13T13:07:20Z
dc.date.available
2017-10-13T12:12:22Z
dc.date.available
2017-10-13T13:07:20Z
dc.date.issued
2017
dc.identifier.isbn
978-3-906327-82-2
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/195430
dc.identifier.doi
10.3929/ethz-b-000195430
dc.description.abstract
Most fineblanked components undergo some sort of heat treatment in order to achieve desired mechanical properties. At the same time it causes unwanted changes in size and shape of the workpiece leading to subsequent working steps on tools or parts. The extent of this thermal distortion depends on many factors such as material, geometry, type of treatment and treatment conditions. Thus, accurate numerical distortion prediction has a high complexity but can potentially save time and costs of reworks on manufacturing tools. Although the present work has a special focus on through-hardening processes, developed methods are applicable to other heat treatments, such as case hardening, with some adjustments. The goal is to bring thermal distortion prediction for fineblanked parts to a level where it can be used to reduce the amount of reworks on tools and parts. In a first step, mechanical and thermal material properties of through-hardenable C60E steel are characterised. The yield curve, anisotropy and continuous cooling temperature (CCT) diagram are experimentally determined. Additionally, a newly developed end quench experiment for sheet metal, a modification of the well-known Jominy-experiment, is used to characterise hardenability. By recording the temperature history during quenching with an infrared camera, the modified Jominy approach can also be used to validated thermal material data in finite element simulations. Subsequently, several experiment series are carried out to find the major influencing factors on thermal distortion, such as residual stresses from the forming or bending step, geometry and batching. All parts are measured before and after their treatment with digital image correlation technique and are then compared with their target geometry. In order to differentiate between stochastic fluctuations and deterministic relationships, the results are statistically analysed. Opposed to bending operations, which influence distortion results, pure fineblanking shows no significant change in distortion. As a consequence the blanking operation may be neglected for distortion prediction. The observable orientation dependency during quenching with a flat, disk-like specimen could not be reproduced with another similar geometry. An additional experiment indicates the distortion reduction capabilities of batching during quenching. Two of the investigated geometries develop multiple different distortion modi although boundary conditions stay the same. Hence, their occurrence frequency seems random. All necessary material input data for heat treatment simulations are assessed and either taken from literature, measured or modelled according to current state of the art methods. Transformation kinetics, describing phase transformation behaviour during heating and quenching, prove to be a key factor in successfully describing the emergence of thermal distortion. As a widely accepted approach in estimating transformation kinetics based on the material’s chemical composition fails to reproduce results of the previously measured CCT diagram, an optimisation procedure is developed. Hardness values and transformation behaviour are optimised consecutively based on controlled quenching experiments. An additional validation of the modified material model, including the modified Jominy experiment, emphasises the significantly improved prediction capabilities for phase structure and hardness values. FE-simulations of the previously conducted experiments are set up and carried out. All simulations are realised with the commercially available FE-software Forge by Transvalor. The simulations enable the tracing of residual stresses, temperature, microstructure, and hardness during heat treatment. The computational time of heat treatment simulations is drastically reduced by neglecting the blanking step as remeshing and element deletion can be avoided while maintaining the same quality of predictions. Distortion and hardness of specimens are compared with measured data. Although numerical simulation results are in line with the experiment series, not all experimentally observed deformation modi can be identified. A buckling analysis is carried out which successfully anticipates the additional modi that are not covered by the regular simulation.
en_US
dc.format
PDF
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
quenching
en_US
dc.subject
Jominy test
en_US
dc.subject
FEM
en_US
dc.subject
Heat Treatment
en_US
dc.subject
CCT
en_US
dc.subject
Fineblanking
en_US
dc.subject
FINEBLANKING (FORMING)
en_US
dc.subject
distortion
en_US
dc.subject
Metallurgy
en_US
dc.subject
C60
en_US
dc.subject
Digital Image Correlation (DIC)
en_US
dc.subject
HARDENING (HEAT TREATMENT)
en_US
dc.title
Heat Treatment Simulation and Experimental Investigation of Thermal Distortion with a Special Focus on Fineblanked Parts
en_US
dc.type
Doctoral Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
ethz.size
185 p.
en_US
ethz.identifier.diss
24376
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02622 - Institut für virtuelle Produktion / Institute of Virtual Manufacturing::03685 - Hora, Pavel / Hora, Pavel
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02622 - Institut für virtuelle Produktion / Institute of Virtual Manufacturing::03685 - Hora, Pavel / Hora, Pavel
en_US
ethz.date.deposited
2017-10-13T12:12:22Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-10-13T13:07:48Z
ethz.rosetta.lastUpdated
2018-11-05T21:53:24Z
ethz.rosetta.exportRequired
true
ethz.rosetta.versionExported
true
ethz.COinS
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