Ductile-to-brittle transition temperature DBTT

Hardness and a ductile-to-brittle transition temperature (DBTT) have also been noted to follow a Hall-Petch relationship (Meyers, and Chalwa, 1984). Ductility increases as the grain size decreases. Decreasing grain size tends to improve fatigue resistance but increases creep rate. Electrical resistivity increases as grain size decreases, as the mean free path for electron motion decreases. 

The effect of polymer blend morphology on the stiffness and toughness of blends of ethylene-co-propylene rubber (EPR) in polyamides (PA) has been the subject of a number of recent papers and patents (1-7). In these toughened blends, the rubber exists as a separate phase of discrete particles. It has been shown that both the rubber particles size and total volume fraction have an effect on toughness and, especially, the ductile-to-brittle transition temperature (DBTT). 

Neutron irradiation of steels used in the construction of nuclear reactor pressure vessels can lead to the embrittlement of these materials - an increase in the ductile-to-brittle transmission temperature and a decrease in the fracture energy - which can limit the NPP. Embrittlement is manifested as a reduction in the fracture toughness and a shift in the ductile-to-brittle transition temperature (DBTT) to higher values, as shown schematically in Figure 4.17. The upper limits on neutron fluence for RPV materials are listed in Table 4.12 [52]. 

Pal] reported mechanical properties (compressive yield strength (0.2%) and creep) and oxidation behavior of Fe-(10-43.5) at.% Al-(10-33) at.% Ti alloys in the temperature range of 20 to 1100°C. The microstracture of these alloys after heat treatment at 800, 900 and 1000°C were either single phase (L2i or C14) or two-phase (L2i -1- C14 or B2 + 72 (Mn23The)). The ductile to brittle transition temperature (DBTT) falls between 675 and 900°C. Oxidation behavior of some alloys at 900C exhibits parabolic behavior. 

CTL close tolerance DBTT ductile-to-brittle transition temperature... 

The impact tests of the wrapper material after irradiation showed a small decrease of the upper shelf energy. The DBTT (Ductile to Brittle Transition Temperature) was hardly influenced. 

The early study of brittle failures, notably those of the Liberty ships, indicated a temperature dependence. This can be illustrated by plotting both fracture stress (of) and yield stress (Oy) against temperature (Fig. 8.81). Below a certain temperature some materials exhibit a transition from ductile to brittle fracture mode. This temperature is known as the ductile-brittle transition temperature DBTT. 

---