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Large inclusions captured by the solidifying shell deteriorate the surface quality of interstitial free steel. To investigate the capture of large inclusion in slab continuous casting, a three-dimensional model coupling flow field, solidification and inclusion motion has been developed. Additionally, to study the effect of in-mold electromagnetic stirring (M-EMS) on large inclusion capture, the electromagnetic field has been also coupled in the model. The results of electromagnetic field indicates its centrally symmetrical distribution on the cross-section, and the electromagnetic force swirls on the cross-section. The effects of M-EMS on flow pattern, solidification and inclusion capture have been discussed. The M-EMS significantly changes the flow pattern and solidifying shell thickness. The inhomogeneous distribution of large inclusions existing in the slab surface in the slab surface are different between the cases with and without M-EMS. Furthermore, the number of captured inclusions increases at 0-0.02 m beneath the wide surface and decreases at 0.02-0.04 m beneath the wide surface in response to the application of M-EMS. Large inclusions in steel were quantitatively analyzed by the galvanostatic electrolysis method. The experimental results are in agreement with the simulation results, suggesting that the model is valid.

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A total number of 44 fatigue tests were conducted under total stain control, 26 for G20Mn5QT cast steel and 18 for butt welds between G20Mn5QT cast steel and Q345B steel. Based on the test results, cyclic stress response, plastic strain energy, strainlife curves and Coffin-Manson equations were presented. Comparing with hot rolled steels widely used in steel construction, the fatigue behaviour of G20Mn5QT cast steel is poor, the reason for which was imputed to the defects caused by the casting process. The welds between G20Mn5QT cast steel and Q345B steel exhibited similar fatigue performance as G20Mn5QT cast steel. Fatigue crack tends to initiate in the heat affected zone (HAZ) at the cast steel. Microstructure observations using optical and scanning electron microscope showed that casting defects are the common fatigue source for both G20Mn5QT cast steel and the butt welds between G20Mn5QT cast steel and Q345B steel.

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Polysilicon microfracture specimens were fabricated using surface micromachining techniques identical to those used to fabricate microelectromechanical systems (MEMS) devices. The nominal critical J-integral (the critical energy release rate) for crack initiation, Jc, was determined in specimens whose characteristic dimensions were of the same order of magnitude as the grain size of the polysilicon. Jc values ranged from 16 to 62 N/m, approximately a factor of four larger than Jc values reported for single crystal silicon.

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