A model for the grain refinement mechanism in equal channel angular pressing of Mg alloy from microstructural studies

Su, Chengqun; Li, Lu; Lai, M.O.

doi:10.1016/j.msea.2006.06.103

Cited by 86 publications

(48 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fine grains or subgrains in the vicinity shear bands and the rearrangement of the stored dislocations to form subgrain boundaries were observed. The findings of previous studies on ECAP processing of AZ31 magnesium alloy demonstrates that nucleation of new grains occurred mainly within the shear zones and along grain boundaries together with rearrangements of dislocations to form subgrain structures, leading to a gradual formation of new grain boundaries as suggested also in [13]. The ring-like selected area diffraction pattern can be indexed as h.p.c.…”

Section: Passes 4 Passesmentioning

confidence: 70%

Microstructure and Mechanical Properties of Mg-2.5%Tb-0.78%Sm Alloy After Ecap and Ageing

Bryła¹,

Рохлин²,

Lityńska‐Dobrzyńska³

et al. 2013

Archives of Metallurgy and Materials

View full text Add to dashboard Cite

The influence of ageing and Equal Channel Angular Pressing (ECAP) on the microstructure and mechanical properties of Mg-2.5%Tb-0.78%Sm alloy has been examined. The microhardness changes during ageing at 200• C show a slight increase. The aged microstructure at maximum hardness contains Mg 12 (Tb,Sm) -metastable β' phase of size about 2-10 nm as dispersed precipitates. The orientation relationship between β' phase and the matrix was found as follows: (0001) M g 110 β , 2110 M g [116] β . The ECAP passes were performed by two procedures: "I" -four passes at 350• C; "II" -one pass at 370• C, second pass at 340• C and third pass at 310• C. The grain size was reduced about 200 times as a results of ECAP process according "I" and "II" procedure. The grain refinement by ECAP improves significantly the compression yield strength and hardness. The Hall-Petch relationship was confirmed basing on microhardness measurements and the grain size after ECAP. The Mg 24 (Tb,Sm) 5 and Mg 41 (Sm,Tb) 5 particles smaller than 150 nm are located mainly at grain and subgrain boundaries and they prevent grain growth during ECAP processing. The microstructure evolution during ECAP can be described as dynamic recovery and continuous and discontinuous dynamic recrystallization.Keywords: magnesium alloys with rare earth metals, ECAP, microstructure, ageing, mechanical properties W pracy przeprowadzono badania mikrostruktury i właściwości mechanicznych stopu Mg-2,5%Tb-0,78%Sm po procesie starzenia oraz po odkształceniu plastycznym metodą ECAP. Starzenie stopu w temperaturze 200• C powoduje niewielki wzrost mikrotwardości. Mikrostruktura stopu starzonego o maksymalnej wartości twardości zawiera metastabilne drobnodyspersyjne wydzielenia Mg 12 (Tb,Sm) -β' o wielkości 2-10 nm. Roztwór stały α-Mg wykazuje następujące zależności krystalograficzne z wydzielonymi cząstkami β': (0001) αM g 110 β , 2110 αM g [116] β . Odkształcenie plastyczne metodą ECAP przeprowadzono stosując dwie procedury: "I" -cztery przejścia w 350• C, "II" -pierwsze w 370• C, drugie w 340• C i trzecie przejście w 310• C. Po procesie ECAP, dla obu procedur, nastąpiło dwustukrotne zmniejszenie wielkości ziarna. Zmniejszenie wielkości ziarna uzyskane metodą ECAP znacząco poprawia twardość oraz granicę plastyczności przy ściskaniu. Stwierdzono zależ-ność Halla-Petcha pomiędzy wartościami mikrotwardości oraz wielkości ziaren uzyskanymi w wyniku odkształcenia metodą ECAP. Cząstki Mg 24 (Tb,Sm) 5 i Mg 41 (Sm,Tb) 5 mniejsze niż 150 nm wydzielone na granicach ziaren i podziaren zapobiegają ich wzrostowi podczas procesu ECAP. Zmiany mikrostruktury zachodzące podczas procesu ECAP można opisać procesami dynamicznego zdrowienia oraz dynamicznej rekrystalizacji.

show abstract

Section: Passes 4 Passesmentioning

confidence: 70%

Microstructure and Mechanical Properties of Mg-2.5%Tb-0.78%Sm Alloy After Ecap and Ageing

Bryła¹,

Рохлин²,

Lityńska‐Dobrzyńska³

et al. 2013

Archives of Metallurgy and Materials

View full text Add to dashboard Cite

show abstract

“…It is interesting to compare the micrographs in Fig. 9 with the work of Su et al [82] for the AZ31 alloy deformed at 473 K (plunger speed not reported). While Fig.…”

Section: Equal Channel Angular Pressing (Ecap)mentioning

confidence: 79%

Influence of thermomechanical processing on the grain size, texture and mechanical properties of Mg-Al alloys

Srinivasarao¹,

Valle²,

Ruano³

et al. 2012

View full text Add to dashboard Cite

The work carried out by the authors over the last decade on the processing, microstructural characterization and the mechanical behaviour of Mg alloys is reviewed. In particular, the potential for grain refinement and for the development of specific textures of large strain hot rolling (LSHR), equal channel angular pressing (ECAP) and accumulative roll bonding (ARB) is discussed. The recrystallization and the deformation mechanisms predominant in Mg alloys are analysed as a function of the grain size and the texture in a wide range of stresses, strain rates and temperatures. Finally, the feasibility of superplastic forming of Mg alloys was examined, taking into account the influence of factors such as grain size stability and microstructural heterogeneities.K e y w o r d s : magnesium alloys,

show abstract

“…Fine grains nucleate around original grain boundaries and inside twins but unrefined areas are still observed away from the boundaries leading to a bimodal grain structure. An earlier paper 4 proposed a mechanism at which recrystallized grains nucleate throughout the original grains and grow until an homogeneous equiaxed structure.…”

Section: Discussionmentioning

confidence: 99%

“…Experiments in a Mg-3% Al-1% Zn alloy revealed a gradual and homogeneous decrease in the average grain size in successive passes of ECAP 4 . The researchers proposed a mechanism of grain refinement in which multiple nuclei of recrystallized grains are formed homogeneously throughout the volume of the processed material and grow until the grain boundaries intercept each other.…”

Section: Equal Channel Angular Pressing (Ecap)mentioning

confidence: 92%

Grain refinement of commercial purity Magnesium processed by Ecap (Equal Channel Angular Pressing)

et al. 2012

View full text Add to dashboard Cite

Grain refinement in magnesium is evaluated in the present paper. Equal Channel Angular Pressing is used to process commercially pure magnesium. Processing was carried out at 523 K which is lower than the temperature used in other papers on the literature. The grain structure was evaluated throughout the deformation zone. The low processing temperature prevents significant grain growth. The evolution of the grain structure is compared to a recent model for mechanism of grain refinement in magnesium. The present results confirm the validity of the model.

show abstract

A model for the grain refinement mechanism in equal channel angular pressing of Mg alloy from microstructural studies

Cited by 86 publications

References 16 publications

Microstructure and Mechanical Properties of Mg-2.5%Tb-0.78%Sm Alloy After Ecap and Ageing

Microstructure and Mechanical Properties of Mg-2.5%Tb-0.78%Sm Alloy After Ecap and Ageing

Influence of thermomechanical processing on the grain size, texture and mechanical properties of Mg-Al alloys

Grain refinement of commercial purity Magnesium processed by Ecap (Equal Channel Angular Pressing)

Contact Info

Product

Resources

About