TY - JOUR

T1 - Non-destructive, Contactless and Real-Time Capable Determination of the α’-Martensite Content in Modified Subsurfaces of AISI 304

AU - Fricke, Lara Vivian

AU - Thürer, Susanne Elisabeth

AU - Jahns, Moritz

AU - Breidenstein, Bernd

AU - Maier, Hans Jürgen

AU - Barton, Sebastian

N1 - Funding information: The scientific work has been supported by the DFG within the research priority program SPP 2086 (Grant Project Number 401800578). The authors thank the DFG for this funding. Open Access funding enabled and organized by Projekt DEAL. This research was funded by the German Research Foundation (DFG) within the research priority program SPP 2086, Grant Number 401800578.

PY - 2022/12

Y1 - 2022/12

N2 - Cryogenic turning can be used to produce deformation-induced martensite in metastable austenitic steels. Martensite exhibits a higher hardness than austenite and increases the wear resistance of the workpiece. In order to reliably induce a desired martensite content in the subsurface zone during the turning process, a non-destructive, contactless and real-time testing method is necessary. Eddy current testing is an electromagnetic method that is non-destructive, non-contact and real-time capable. Furthermore, eddy current testing has been integrated into production processes many times. Eddy current testing can be used to detect the transformation of paramagnetic austenite to ferromagnetic α′-martensite based on the change in magnetic and electrical properties. Thus, the newly formed subsurface can be characterized and the manufacturing process can be monitored. The objective of this study was to understand the correlation of eddy current testing signals with newly formed α′-martensite in the subsurface of AISI 304 and to quantify the amount formed. The measurements were performed within a machining center. Several methods for reference measurement of martensite content are known in the literature. However, depending on the method used, large discrepancies may occur between the determined contents. Therefore, different analytical methods were used for reference measurements to determine the total martensite content in the subsurface. Metallographic sections, magnetic etching, Mössbauer spectroscopy, and X-ray diffraction with two different analytical methods were employed. Based on the correlation between the eddy current testing signals and the α′-martensite content in the subsurface, process control of the manufacturing process can be achieved in the future.

AB - Cryogenic turning can be used to produce deformation-induced martensite in metastable austenitic steels. Martensite exhibits a higher hardness than austenite and increases the wear resistance of the workpiece. In order to reliably induce a desired martensite content in the subsurface zone during the turning process, a non-destructive, contactless and real-time testing method is necessary. Eddy current testing is an electromagnetic method that is non-destructive, non-contact and real-time capable. Furthermore, eddy current testing has been integrated into production processes many times. Eddy current testing can be used to detect the transformation of paramagnetic austenite to ferromagnetic α′-martensite based on the change in magnetic and electrical properties. Thus, the newly formed subsurface can be characterized and the manufacturing process can be monitored. The objective of this study was to understand the correlation of eddy current testing signals with newly formed α′-martensite in the subsurface of AISI 304 and to quantify the amount formed. The measurements were performed within a machining center. Several methods for reference measurement of martensite content are known in the literature. However, depending on the method used, large discrepancies may occur between the determined contents. Therefore, different analytical methods were used for reference measurements to determine the total martensite content in the subsurface. Metallographic sections, magnetic etching, Mössbauer spectroscopy, and X-ray diffraction with two different analytical methods were employed. Based on the correlation between the eddy current testing signals and the α′-martensite content in the subsurface, process control of the manufacturing process can be achieved in the future.

KW - Eddy current testing

KW - Magnetic etching

KW - Martensite content quantification

KW - Mössbauer spectroscopy

KW - Subsurface hardening

KW - X-ray diffraction

UR - http://www.scopus.com/inward/record.url?scp=85139694675&partnerID=8YFLogxK

U2 - 10.1007/s10921-022-00905-x

DO - 10.1007/s10921-022-00905-x

M3 - Article

AN - SCOPUS:85139694675

VL - 41

JO - Journal of Nondestructive Evaluation

JF - Journal of Nondestructive Evaluation

SN - 0195-9298

IS - 4

M1 - 72

ER -