An evaluation is presented of the influence of welding on the uniaxial creep rupture behaviour of some ferritic, martensitic and austenitic creep resistant materials. After a description of evaluation the most reliable figures for the effect of welding will be presented in the form of two parameters. One is the strength reduction factor (SRF) for design conditions. The other is the lifetime reduction factor (LRF) for judging the lifetime of welded components at normal design stresses. Two criteria will be introduced to judge whether the introduction of a stress reduction factor for design of welded components is advisable. The needs for further research in this field are indicated.Auswirkungen des SchweiBprozesses auf die Zeitstandfestigkeit. Der EinfluB des SchweiBens auf das einachsige Zeitstandverhalten wird ausgewertet und tor einige ferritische, martensitische und austenitische warmfeste Legierungen prasentiert. Im AnschluB an eine Beschreibung der Auswertemethoden werden die zuverlassigsten Zahlen, die diesen EinfluB quantifizieren, in Form zweier Parameter dargestellt. Hierbei handelt es sich einerseits um den Festigkeitsreduktionsfaktor (SRF) tor Entwurfbedingungen und andererseits um den Lebensdauerreduktionsfaktor (LRF) zur Beurteilung der Lebensdauer geschweiBter Bauteile bei normalen Entwurfspannungen. Zwei Kriterien, die beurteilen, inwieweit die BerOcksichtigung eines SchweiBnahtfaktors empfehlenswert ist, werden eingetohrt. AbschlieBend wird weiterer Forschungsbedarf skizziert.

No abstract

If a metal is deformed in one direction and afterwards deformed in the opposite direction, the yield value has decreased. This decrease is called the Bauschinger effect (RE.). This effect has been measured by many investigators for polycrystalline metals 1) and single crystals 2).For polycrystalline metals it is usually explained by the production of internal stresses in the metal during unloading, caused by the different orientation of the grains 3). The B.E., however, has also been measured for-single crystals. This may be explained by the back-stresses produced by the mutual repulsion between piled-up dislocations 4). Zen e r 3) makes the interesting prediction, that the RE. should be removed to a large extent by low-temperature annealing.If a wire is twisted. an extra RE. is introduced. caused by the inhomogeneous deformation. The B.E. as due to the different deformation of the grains in the polycrystalline metal and to the twisting has been calculated by R a h I f s and 11 a sin g 1) under certain simplifications.We have studied the influence of the amount of deformation, the temperature and preliminary stretching on the RE. for copper wires with the aid of a torsion apparatus. The measurements have been carried out on wires of about 44 rom length and about I mm diameter of electrolytic copper (99.98%). Initially these wires have been annealed for It hour at 550°C in vacuo, and in most experiments this has been followed by a prestrain of 8% by stretching.The results are shown by plotting the shear stress T in the outer -100-

No abstract