Characterisation of Progressive Material Deformation at the Crack Tip of a Carbon Steel Piping Using Barkhausen Noise Analysis
H.N. Singh, A.B. Tamhane, R.S. Shriwastaw, K.C. Sahoo, Bhabha Atomic Research Centre, India
ABSTRACT
Carbon steel pipings are used as primary coolant circuit pressure pipings in Pressurised Heavy Water Reactors (PHWRs). Structural integrity of these pipings is of vital importance to the safe operation of the reactors. A suitable NDT technique is needed for in-situ measurement and periodic assessment of stress field and material deformation in such pipings. Stress and plastic deformation generate characteristic Magnetic Barkhausen Noise (MBH) signals in ferromagnetic materials, which can be used for assessing condition of material. MBH measurements were carried out during slit burst test of a carbon steel pipe around the progressive crack tip at changing pressure. MBH measurements were taken while increasing pressure in carbon steel pipe section till the burst occurred. The progressive changes in Root Mean Square (RMS) value of MBH signal, collected on pipe at both sides of cracked region with material deformation, was mapped using 3D imaging. This paper presents details of experimental set-up and measurement carried out in relationship with plastic deformation in the material. The drop in RMS value of MBH was observed around the crack tip where the plastic deformation in the materials was progressively taking place. The MBH analysis technique can be very gainfully employed for non-destructive evaluation of stress field and material deformation in ferromagnetic steel components during internal pressurisation condition.
Publication Source: 3nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, November 14-16, 2001, Seville Spain. Publisher: Tecnatom s.a. - [Homepage]
