Acoustic Emission (AE) associated with uniaxial tensile tests was used to study failure mechanisms in CrN and CrN/NbN coated specimens.When a very fast release of elastic energy occurs during a loading cycle it generates waves in the range of ultrasound (usually between 20kHz and 1MHz). This short, transient acoustic emission event produced can be detected and measured so to investigate local damage within the material in a dynamic way during its load history. Tensile tests were performed by the use of an MTS (Alliance RT/10) Testing Machine on three micrometers thick CrN and CrN/NbN coated specimens deposited by reactive cathodic arc evaporation onto X5CrNiMo 17 12. Acoustic measurements were also made on one set of non-coated substrate specimens in order to discriminate events arisen in the substrate during the plastic deformation process.Signals were collected by four transducers: two “data” sensors, placed on the specimens surface enclosing the area of interest; two “guard” sensors to discriminate from sources originating outside. AE/strain curves obtained for all specimens showed a good repeatability and different types of acoustic events were evaluated in terms of amplitude and absolute energy. Moreover, acoustic emission results were correlated with microscopy evidences. Failure mechanisms and cracks propagation paths were characterized by SEM/EDS, both in plan view and cross section; the role of surface and bulk defects was evidenced and different behaviour was found in the case of multilayered structure.
Pecchio, C., Crippa, L., Lizundia, A., Bemporad, E. (2004). Acoustic Emission Monitoring during Tensile Tests on CrN and CrN/NbN Coated Specimens, poster alla conferenza. In “The International Conference On Metallurgical Coatings And Thin Films ICMCTF 2004” April 19 - April 23, 2004.. / : /.
Acoustic Emission Monitoring during Tensile Tests on CrN and CrN/NbN Coated Specimens, poster alla conferenza
BEMPORAD, Edoardo
2004-01-01
Abstract
Acoustic Emission (AE) associated with uniaxial tensile tests was used to study failure mechanisms in CrN and CrN/NbN coated specimens.When a very fast release of elastic energy occurs during a loading cycle it generates waves in the range of ultrasound (usually between 20kHz and 1MHz). This short, transient acoustic emission event produced can be detected and measured so to investigate local damage within the material in a dynamic way during its load history. Tensile tests were performed by the use of an MTS (Alliance RT/10) Testing Machine on three micrometers thick CrN and CrN/NbN coated specimens deposited by reactive cathodic arc evaporation onto X5CrNiMo 17 12. Acoustic measurements were also made on one set of non-coated substrate specimens in order to discriminate events arisen in the substrate during the plastic deformation process.Signals were collected by four transducers: two “data” sensors, placed on the specimens surface enclosing the area of interest; two “guard” sensors to discriminate from sources originating outside. AE/strain curves obtained for all specimens showed a good repeatability and different types of acoustic events were evaluated in terms of amplitude and absolute energy. Moreover, acoustic emission results were correlated with microscopy evidences. Failure mechanisms and cracks propagation paths were characterized by SEM/EDS, both in plan view and cross section; the role of surface and bulk defects was evidenced and different behaviour was found in the case of multilayered structure.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
