Critical stress for delamination fracture in HSLA steels

AbstractAnalysis of the behaviour of four classes of HSLA steels showing delaminations led to the conclusion that this type of fracture generally follows a critical tensile stress criterion, whose value has been accurately measured in all cases.Plastic anisotropy and elongated non-metallic inclusions, while they appreciably increase the likelihood of delaminations occurring, do not seem to be the causes of the necessary lowering of the critical fracture stress along the through-thickness direction. Instead, it appears that an important source of delamination fracture might be the dimensional anisotropy of the microstructural unit which controls fracture: polygonal or acicular ferrite ‘grain’ (transgranular cleavage) or prior austenite grain (intergranular failure).

[1]  P. L. Pratt,et al.  On the plastic deformation of charpy specimens prior to general yield , 1966 .

[2]  J. M. Alexander,et al.  On the yielding of a rigid/plastic bar with an Izod notch , 1962 .

[3]  On stress intensifications in specimens of charpy geometry prior to general yield , 1967 .

[4]  C. A. Rau,et al.  A general model to predict the elastic-plastic stress distribution and fracture strength of notched bars in plane strain bending☆ , 1968 .

[5]  D. Ewing,et al.  Calculations on the bending of rigid/plastic notched bars , 1968 .

[6]  R. T. Weiner,et al.  ‘Arrowhead’ fractures in controlled-rolled pipeline steels , 1974 .

[7]  David R. Owen,et al.  An elastic-plastic stress analysis for a notched bar in plane strain bending , 1971 .

[8]  G. Buzzichelli,et al.  Effect of plastic anisotropy on the occurrence of “separations” on fracture surfaces of hot-rolled steel specimens , 1976 .

[9]  J. F. Knott,et al.  Cleavage Fracture in Prestrained Mild Steel , 1975 .

[10]  J. Embury,et al.  Some aspects of the fracture behaviour of high strength, low alloy steels , 1975 .

[11]  W. B. Morrison,et al.  Influence of testing direction on the mechanical properties of vvrought steel , 1975 .

[12]  D. Hawkins.  Cleavage separations in warm-rolled lowcarbon steels , 1976 .

[13]  J. Malcolm Gray,et al.  Processing and properties of low carbon steel , 1973 .

[14]  A. Mascanzoni,et al.  Microstructure and cleavage resistance of low-carbon bainitic steels , 1977 .