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Master thesis proposal – Residual stresses and subsequent deformations in cast iron

Aim
Study residual stresses and subsequent deformations in cast iron and how these are affected by geometrical variations and different solidification structures.

Background
Residual stresses are the stresses that remain in the component after the load has been removed. These may result from fabrication processes or due to overload yielding. In cast components these stresses can arise due to constraints during solidification when both cast iron and sand mold undergoes volumetric changes. Residual stresses are usually undesirable because if added to in-service stresses the maximum tolerable load may be exceeded. There are some different methods to investigate these stresses and one of them is based on hole-drilling together with strain gauges to measure the deformation that form during the hole-drilling. It is important to understand how residual stresses are formed in order to better predict and simulate how the component will deform.

Planned work
In the proposed thesis work test pieces made of lamellar graphite iron (LGI) and spheroidal graphite iron (SGI) will be investigated regarding deformation behavior and residual stresses.

• Literature survey about residual stresses in cast iron and how residual stresses are measured.
• Measure and characterize test-piece geometries.
• Measure residual stresses using the hole-drilling method.
• Additional experiments to fill gaps in the data.
• Microstructure investigations/material characterization.
• Cut the test pieces and investigate the deformation.
• Simulate residual stresses and compare with the measured stresses.
• Report and presentation.

Qualifications
Good knowledge in materials engineering and mechanical engineering. Knowledge about casting and cast iron production is meriting.

Application
The application should include: Application letter, short CV and transcript of records, and should be sent to: lennart.elmquist@swerea.se

Last date for application: 2016-12-16

The workload can be modified to be suitable for one or two students.

For further information, please contact Lennart Elmquist, Swerea SWECAST: lennart.elmquist@swerea.se, 036-301272

ANSÖKAN