On the Embrittlement and Toughness of High Purity Fe-30Cr-2Mo Alloy

Experiments were conducted to explain unexpected embrittlement phenomena encountered in fabricating a high purity Fe-30Cr-2Mo alloy. By means of a hydrostatic tensile test with a Bridgman-Type specimen it was found that the fracture behaviour of the alloy is highly dependent on stress state. Under conditions of low triaxial stress, the alloy displays excellent ductility. Under conditions of high triaxial stress, however, the alloy shows less strain to fracture and a transition from ductile to cleavage fracture. The toughness of the Fe-30Cr-2Mo alloy can be significantly improved by thermomechanical processing

Progress in the Development of Failure Maps : Negative Pressure-Strain-Temperature Diagram

The paper describes the development of failure maps. These are maps with hydrostatic tensile stress as one axis and fracture strain as one axis and temperatures as the other, showing the fields of dominance of a given micromechanism of fracture : cleavage, ductile fracture, intergranular fracture, and so on. Maps are presented for three structural steels, one high purity chromium stainless steel, one high strength aluminium alloy and one high strength titanium alloy. They give an overview of the micromechanisms by which a given material may fail, and help identify the one most likely to be dominant in a given experiment, or an engineering application. They should give guidance in selecting materials for low-temperature use and in selecting processing parameters in deformation processing of the materials

The Effect of Hydrostatic Tensile Stress on Fracture in Some Structural Alloys

Using Bridgman-type tensile specimens with natural necking profile, the characteristics of fracture in some structural alloys are summarized as failure maps which can express the characteristics as a curved surface divided by the dominance of micromechanism of fracture in three-dimensional space (fracture strain-temperature-hydrostatic tensile stress). (SCI. REP. RITU, A-Vol. 29, No. 1, 1980, p. 50) In this paper, interrelations between fracture strain and hydrostatic tensile stress are analyzed and discussed in various fracture modes and examples of application of the failure map to the estimation of toughness of materials and to the prediction of the occurrence of internal damage during wire drawing process are presented

Ruckbildung der Guinier-Preston-Zonen in einer Al-Mg_2Si-Legierung wahrend einer Wechselbeanspruchung und ihre Neubildung nach Entlastung

Eine kaltausgehartete Al-Mg_2-Si-Legierung wurde schwingend beansprucht und anschliessend bei Raumtemperatur ausgelagert. Sowohl wahrend der Wechsel-beanspruchung als auch der Auslagerung nach der Entlastung wurde die Widerstandsanderung der Legierung gemessen. Der Widerstand nimmt durch die Wechselbeanspruchung ab. Es ist dies eine Folge der Ruckbildung der G.-P.-Zonen. Wahrend der Raumtemperaturlagerung nach der Entlastung wurden drei Stadien beobachtet, eine Abnahme, die den Ausheilungsprozess der durch die Wechselbeanspruchung erzeugten uberschussigen Leerstellen entspricht, eine Zunahme, die mit der Wiederbildung der G.-P.-Zonen verbunden ist, und eine erneute langsame Abnahme, die auf dem Wachstum der G.-P.-Zonen beruht