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Modes of fracture in temper embrittled steels
Vol. 8, No. 10
ABSTRACTS OF ARTICLES TO APPEAR IN ACTA MET
A pulse echo technique using thin line ultrasonics has been used to measure the variation with carbon content of austenite. The measurements span the austenite phase field of the Fe-Fe3C diagram up to the y-Fe3C phase boundary at 1OOO'C and 105OOC. The resulting data have been used to calculate the manner in which the partial thermodynamic properties of the C-atoms would vary with composition if the volume of the solid solution were held constant The results found indicate the extent of the error which arises when the thermodynamic functions calculated from models involving constant interaction energies are compared with experimental thennodynamic data measured at constant pressure. 6.
GRUNDZGGE DER THEORIE PERIODISCHER FACETTEN G. Frohberg Institut fur Metallforschung (Metallphysik) Technische Universitat Berlin P. Adam Institut fur Metallforschung (Metallphysik) Technische Universitat Berlin
7.
A theory of periodic faceting has been developed. The main features of the theory are 1) faceting is due to orientation dependent surface mass flows caused by electrotransport or thermotransport; a minimalization of surface energy does not take place; 2) the development of the characteristic periodicity of facets is shown to be due to a maximum growth rate of the corresponding Fourier-component of the initial surface; 3) different drift velocities across ledges and terraces are proposed as a model for the orientation dependence of surface mass flow.
A NUMERICAL SOLUTION OF THE DIFFUSION EOUATION RESULTING FROM THE VOID THEORY OF THE TRAPPING OF HYDROGEN IN IRON AND STEEL D. M. Allen-Both Dept. of Applied Physics Sheffield Polytechnic C. Atkinson Dept. of Mathematics Imperial College University of London B. A. Bilby Dept. of the Theory of Materials University of Sheffield Received July 8, 1974
Various forms for the diffusion equation resulting from the void theory of the trapping of hydrogen in iron and. steel are considered, and a numerical solution of one of these is given; Using this the quantity of hydrogen evolved in a given time from a cylindrical specimen is calculated and compared with experimental observations. It is shown that the model predicts satisfactorily a number of properties of the observed apparent diffusion coefficient. 8.
Received March 29, 1974
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MODES OF FRACTURE IN TEMPER EMBRITTLED STEELS H. Ohtani Sumitomo Metal Industries Ltd. Central Research Labs. Amagasaki, Japan C. J. McMahon, Jr. Dept. of Metallurgy & Materials Science & LRSM University of Pennsylvania Philadelphia, Pa.
Metallographic and fractrographic observations in a low carbon 3.5 pet Ni-1.7 pet Cr steel doped with antimony or phosphorus show that temper embrittlement can involve low energy fractures along grain
:lii
ABSTRACTS OF ARTICLES TO APPEAR IN ACTA MET
boundaries other than prior austenitic grain boundaries. Examples given here are: (1) the boundaries of blocky ferrite and upper bainite formed during austenitic decomposition, and (2) the grain boundaries of the equiaxed ferrite formed by complete recrystallizationbelow the eutectoid temperature. These observations show that the.occurrenceof prior austenite grain boundary fracture, which has been considered an essential and almost classical aspect of temper embrittlement, is actually not an essential feature of the problem. Prior austenite grain boundary fracture can be made to occur in the present low carbon steel (when temper-embrittled)if these boundaries are sufficientlywell preserved during austenite decomposition, e. g., by the very high quenching rates achieved near a free surface, or due to the presence of sufficient phosphorus, which segregates in the austenite phase and retards the nucleation of ferrite at austenite grain boundaries.
Vol. 8, No. 10
ABSTRACTS OF ARTICLES TO APPEAR IN ACTA MET
A pulse echo technique using thin line ultrasonics has been used to measure the variation with carbon content of austenite. The measurements span the austenite phase field of the Fe-Fe3C diagram up to the y-Fe3C phase boundary at 1OOO'C and 105OOC. The resulting data have been used to calculate the manner in which the partial thermodynamic properties of the C-atoms would vary with composition if the volume of the solid solution were held constant The results found indicate the extent of the error which arises when the thermodynamic functions calculated from models involving constant interaction energies are compared with experimental thennodynamic data measured at constant pressure. 6.
GRUNDZGGE DER THEORIE PERIODISCHER FACETTEN G. Frohberg Institut fur Metallforschung (Metallphysik) Technische Universitat Berlin P. Adam Institut fur Metallforschung (Metallphysik) Technische Universitat Berlin
7.
A theory of periodic faceting has been developed. The main features of the theory are 1) faceting is due to orientation dependent surface mass flows caused by electrotransport or thermotransport; a minimalization of surface energy does not take place; 2) the development of the characteristic periodicity of facets is shown to be due to a maximum growth rate of the corresponding Fourier-component of the initial surface; 3) different drift velocities across ledges and terraces are proposed as a model for the orientation dependence of surface mass flow.
A NUMERICAL SOLUTION OF THE DIFFUSION EOUATION RESULTING FROM THE VOID THEORY OF THE TRAPPING OF HYDROGEN IN IRON AND STEEL D. M. Allen-Both Dept. of Applied Physics Sheffield Polytechnic C. Atkinson Dept. of Mathematics Imperial College University of London B. A. Bilby Dept. of the Theory of Materials University of Sheffield Received July 8, 1974
Various forms for the diffusion equation resulting from the void theory of the trapping of hydrogen in iron and. steel are considered, and a numerical solution of one of these is given; Using this the quantity of hydrogen evolved in a given time from a cylindrical specimen is calculated and compared with experimental observations. It is shown that the model predicts satisfactorily a number of properties of the observed apparent diffusion coefficient. 8.
Received March 29, 1974
li
MODES OF FRACTURE IN TEMPER EMBRITTLED STEELS H. Ohtani Sumitomo Metal Industries Ltd. Central Research Labs. Amagasaki, Japan C. J. McMahon, Jr. Dept. of Metallurgy & Materials Science & LRSM University of Pennsylvania Philadelphia, Pa.
Metallographic and fractrographic observations in a low carbon 3.5 pet Ni-1.7 pet Cr steel doped with antimony or phosphorus show that temper embrittlement can involve low energy fractures along grain
:lii
ABSTRACTS OF ARTICLES TO APPEAR IN ACTA MET
boundaries other than prior austenitic grain boundaries. Examples given here are: (1) the boundaries of blocky ferrite and upper bainite formed during austenitic decomposition, and (2) the grain boundaries of the equiaxed ferrite formed by complete recrystallizationbelow the eutectoid temperature. These observations show that the.occurrenceof prior austenite grain boundary fracture, which has been considered an essential and almost classical aspect of temper embrittlement, is actually not an essential feature of the problem. Prior austenite grain boundary fracture can be made to occur in the present low carbon steel (when temper-embrittled)if these boundaries are sufficientlywell preserved during austenite decomposition, e. g., by the very high quenching rates achieved near a free surface, or due to the presence of sufficient phosphorus, which segregates in the austenite phase and retards the nucleation of ferrite at austenite grain boundaries.
Vol. 8, No. 10