Evaluation and Identifying the Ductile Fracture Area of X70 Steel from DWTT Broken Specimens

• DOI: 10.1016/j.prostr.2016.06.463
• Publication Date: 2016-07-22T07:57:18Z
• Authors: Pavel Skalny
• Keywords: DWTT specimen; Fracture; 0203 mechanical engineering; probability; 596 918 507; 02 engineering and technology; cluster analysis

AbstractFracture surfaces of X70 steel DWTT broken samples are analyzed using statistical methods and fractal concepts. Besides of fractal geometry concept the new approach based on the normal vectors analysis is presented. The fracture surface is covered by a triangle net. For every triangle the normal vector is determined. Fractal dimension is significantly correlated to the angular deviation of neighboring normal vectors. The mean value of deviation angles and fractal dimension is lower for ductile than for brittle fracture areas. The k-means cluster analysis and multivariate probability distribution are applied to determine the local characteristics of the fracture surface. The fracture surface map of ductile fracture probability and k-means clusters highly corresponds to the real placement of ductile and brittle fracture area on fracture surface of the broken sample. Newly presented statistical methods applied on the fracture surface of DWTT broken samples are useful tools for objective evaluation of ductile fracture percentage.