Substructural Strengthening by Hot Working in Two &lt;I&gt;FCC&lt;/I&gt; Materials

Ueki, Masaaki; Nakamura, Tadahisa

doi:10.2320/matertrans1960.17.139

Cited by 14 publications

(2 citation statements)

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“…It is not comparable to a Hall-Petch relationship since each flow stress is at a different temperature so that c is not the strength of material without substructure and may be zero. In the data for AI, the strength is greater at a given subgrain size for commercial material and the strengthening coefficient e is larger [40,47,49,[52][53][54] due to specific impurities [25,55,56]. Alternatively, at a given Z, the substructure is much finer because of impurity particles and hence the strength is considerably greater.…”

Section: Subgrains Dynamic Recovery Andflolv Stressmentioning

confidence: 99%

“…values generally lie respectively between 2 and 5 and 0.04 and 0.06 MPa -I [8,25,98,100]. The activation energy rises regularly with Mg content from 130-160kJjmoi to IS0-200kJjmoi [6,8,21,25,43,54,80,97,100]. For the commercial purity Mg alloys, the values rise more rapidly but with much more scatter [8,25,73].…”

Section: Flow Stress Dependence On Mg Content Temperature and Strainmentioning

confidence: 99%

See 1 more Smart Citation

Application of Hot Workability Studies to Extrusion Processing: Part II. Microstructural Development and Extrusion of Al, Al–Mg, and Al–Mg–Mn Alloys

McQueen¹,

Celliers²

1996

Canadian Metallurgical Quarterly

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In uniform hot working tests, the flow curves strain harden to a steady state plateau that depends on temperature and strain rate. The underlying mechanism is dynamic recovery which rises with strain to balance the work hardening, resulting in subgrains that are larger and more perfect as T rises and E falls. Subgrains are observed in the extrudate following the pattern established in hot workability tests. Moreover, their formation in the upset billet and throughout the deformation zone has been examined as a means to delineate its thermal and mechanical development. Substructure in the extrudate substantially improves its mechanical properties. With increasing Mg solute, substructure recovery is reduced so that the strength and the tendency for recrystallization are increased. Moreover, in alloys above 5% Mg, most notably containing large Mn-rich constituent particles, dynamic recrystallization nuclei form in the most intensely strained regions of the deformation zone and also speed up static recrystallization in the extrudate.Resume-Lors d'essai de formage a chaud uniforme, les courbes d'ecoulement se durcissent par ecrouissage jusqu'a un plateau constant qui depend de la temperature et du taux de deformation. Le mecanisme sousjacent est la restauration dynamique qui augmente avec la deformation pour balancer Ie durcissement par ecrouissage, resultant en sous-grains qui sont plus gros et plus parfaits a mesure que la T s'eleve et que f s'abaisse. On observe des sous-grains dans la forme d'extrusion, suivant Ie modele etabli lors d'essais de formage a chaud. De plus, on a examine leur formation dans la billette refoulee et dans toute la zone de deformation, comme un moyen de delimiter leur developpement thermique et mecanique. La sous-structure dans la forme d'extrusion ameliore substantiellement ses proprietes mecaniques. Avec une augmentaion du solute de Mg, la restauration de la sous-structure est reduite de telle sorte que la resistance et la tendance ala recristallisation sont augmentees. De plus, dans les alliages de plus de 5% Mg, contenant visiblement de grosses particules constituantes riches en Mn, des noyaux de recristallisation dynamique se forment dans les regions les plus intensement deformees de la zone de deformation et aussi augmentent la vitesse de recrisallisation statique de la forme d'extrusion.

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