Evaluation of Microstructural Changes of S235 Steel after Rolling on the Basis of Microscopic Observations and Eddy Current Non-Destructive Method

Abstract

The aim of the study was to determine the microstructure and residual stress changes which appears in the S235 steel (which is designed for operating in elevated temperatures) during cold rolling. The changes of orientation, both morphological and crystallographic, are occurring as a result of the rolling process. Analysis of the results allowed to determine the change in grain morphology (size, shape), determination of grain morphology of the rolling direction and determination of crystallographic texture. The dislocation density present in the material before and after the cold rolling process was estimated on the basis of dislocation structure images obtained via transmission electron microscope. The observed microstructural changes were correlated with the results of nondestructive testing using eddy current method. They allowed for the identification of the state of stress measured on three different surfaces of the rolled sheet (parallel and perpendicular to the rolling direction). As the result the usability of using the non -destructuve techniques of stress level determination was proved.

Ocena twardości warstw nawęglanych i hartowanych indukcyjnie na stali AMS 6414 z zastosowaniem magnetycznych technik nieniszczących

“…Skutkuje to ograniczeniem głębokości wnikania prądów w stali ferromagnetycznej do kilkuset mikrometrów, czyli w zakresie grubości warstw hartowanych. Podobne badania, z zastosowaniem prądów wirowych prowadzono także w zakresie oceny stopnia uszkodzenia zmęczeniowego [1,2], stanu składowych naprężenia resztkowych [3], czy też grubości warstw hartowanych [4,5]. Z kolei metoda szumów Barkhausena wykorzystywana była przez autorów m in.…”

Internal Cracks and Non-Metallic Inclusions as Root Causes of Casting Failure in Sugar Mill Roller Shafts

“…It was identified that quality check results are mostly requested from the sugar industry, while a precise specification of the final product is hardly requested [13]. Several destructive/non-destructive techniques are reported in literature, focusing on the major causes that lead to defective production, such as magnetic particle testing [14], ultrasonic testing [15], crystallographic testing [16] and scanning electron microscopy (SEM). The in-depth porosity effect on the fatigue life of the A319 alloy was discussed by Zhang et al [17].…”