β Scribed by H.D. Chandler
No coin nor oath required. For personal study only.
Transient creep curves were obtained from mild steel and copper specimens which had been work hardened by cycling. Results are presented in terms of an "overstress" model in which strain rates are related to differences between the actual stress and the corresponding stress-strain point on a quasi-static stress-strain curve. It is further shown that a semi-empirical equation used to describe steady state plastic deformation can be adapted to describe transient behaviour when re-written in terms of the 'overstress' rather than the actual stress.
R&mm&-Nous avons obtenu des courbes de fluge transitoire dans l'acier doux et dans le cuivre durcis par des cycles de d&formation. Nous prksentons les rksultats en terme d'un modele de "surcontrainte" dans lequel les vitesses de d&formation sont likes B la diffkrence entre les v&tables contraintes et le point correspondant de la contrainte4formation sur une courbe contrainte4bformation quasi-statique. Nous montrons d'autre part que I'on peut adapter une kquations semi-empirique utilisie dans la description de la dbfoxmation plastique stationnaire pour dircrire le comportement transitoire en l'itcrivant & nouveau en fonction de la "surcontrainte" plut6t que de la contrainte rbelle.
Zusammenfassung-An zyklisch verfestigten Kupfer-und kohlenstoffarmen Stahlproben wurden transiente Kriechkurven gemessen. Die Ergebnisse werden anhand des "uberspannungs"-Modells dargestellt, bei dem die Dehnungsraten mit Unterschieden zwischen der anliegenden Spannung und der entsprechenden Spannung auf einer quasi-statischen Spannungs-Dehnungskurve zusammenhlngen. AuDerdem wird gezeigt, da8 eine fiir die Beschreibung der stationlren plastischen Verformung benutzte Gleichung auf die Beschriebung des ubergangsverhaltens angepal3t werden kann, wenn statt der tatsiichlichen Spannung die "tiberspannung" verwendet wird.
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Crack growth rate and crack closure during fatigue of type 304 stainless steel are measured with an optical microscope and television camera. Based on the crack closure data an effective stress intensity range AKFR is calculated. The da/da vs A&-curves indicate that crack closure could account for t
Aluminium-thiourea (Al-thi) inhibitors were found to provide good inhibition of mild steel in water of a high specific salinity (1.0% Na,SO,) considered characteristic for recirculating water of zero-discharge cooling systems in steam plants. As in a real cooling system this water would contain calc