Hardening (metallurgy)

About: Hardening (metallurgy) is a research topic. Over the lifetime, 25584 publications have been published within this topic receiving 376012 citations.

Hardening of new resin cements cured through a ceramic inlay.

Abstract: This study investigated the degree of hardening achieved through self-curing only and through dual-curing a group of eight new resin-based cements In addition, the effect of ceramic inlay thickness on cement hardness was determined Disk specimens measuring 6 mm in diameter and 25 mm thick were prepared from eight cements: Adherence, Choice, Duolink, Enforce, Lute-It, Nexus, Resinomer, and Variolink Eight specimens were prepared from each material; half were self-cured, while the remainder were dual-cured Knoop hardness measurements were then made at 1-hour, 1-day, and 1-week intervals In addition 12 specimens of the same dimensions were prepared from each cement and were dual-cured through ceramic spacers of varying thickness (1-6 mm) Hardness measurements were made as above ANOVA showed significant differences in hardness of self-cured versus dual-cured specimens for all cements (P < 00001) Significant differences were also found in the hardness of specimens dual-cured through ceramic spacers 2-3 mm in thickness or more compared with those that were dual-cured without spacer It is concluded that for some materials self-curing alone was not adequate to achieve sufficient hardening; cement hardness was significantly reduced when ceramic inlay thickness was 2-3 mm or more

Grain boundary versus transgranular ductile failure

Abstract: The competition between intergranular and intragranular fracture is investigated using a bilayer damage model, which incorporates the relevant microstructural features of aluminium alloys with precipitate free zones (PFZ) nearby the grain boundary. One layer represents the grain behaviour: due to precipitation, it presents a high yield stress and low hardening exponent. The other layer represents the PFZ which has the behaviour of a solid solution: it is much softer but with a much higher strain hardening capacity. In both layers, void growth and coalescence is modelled using an enhanced Gurson-type model incorporating the effects of the void aspect ratio and of the relative void spacing. The effects on the ductility (i) of the flow properties of each zone, (ii) of the relative thickness of the PFZ, and (iii) of the particles spacing and volume fraction in the PFZ are elucidated. Comparisons are made with experimental data. Based on the previous analysis, qualitative understanding of trends in the fracture toughness of aluminium alloys can be gained in order to provide a link with the thermal treatment process. (C) 2003 Elsevier Science Ltd. All rights reserved.