Microstructure and mechanical properties of high strength Al–Zn–Mg–Cu alloys used for oil drill pipes

Feng, Chuanqi; Shou, Wenbin; Liu, Huiqun; Yi, Danqing; Feng, Yaorong

doi:10.1016/s1003-6326(15)63994-2

Cited by 30 publications

(12 citation statements)

References 18 publications

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“…The mechanical properties logically depend on chemical composition of the alloys (mainly on Zn-and Mg-content) as well as on thermomechanical treatment and then the decomposition sequence could be more complicated [2][3][4][5][6][7][8][9]. The decomposition sequence should also contain metastable semicoherent T phase (Al 2 Zn 3 Mg 3 -hexagonal structure) and equilibrium T phase (Al 2 Zn 3 Mg 3cubic structure), too [8,10,11]. Yang et al [8] reported that an Al-7.60Zn-2.55Mg (wt.%) alloy with a characteristically high Mg/Zn mole ratio can be strengthened by the T -phase precipitates.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cold Rolling on Precipitation Processes in Al-Zn-Mg(-Sc-Zr) Alloy

et al. 2018

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The effect of cold rolling (6% and 21%) on electrical, mechanical and thermal properties and microstructure of the classical mould-cast Al-Zn-Mg alloy with and without Sc,Zr-addition were studied. Samples were isochronally annealed up to 460 • C. Electrical resistivity and microhardness together with differential scanning calorimetry measurements were compared to microstructure development. The initial microhardness values of the alloys reflect the deformation degree. Distinct changes in electrical resistivity as well as in heat flow of the alloys studied are mainly caused by dissolution of Zn,Mg-rich Guinier-Preston zones and subsequent precipitation of the metastable η phase. Precipitation of this phase is responsible for a slight hardening effect. Probably an easier diffusion of Zn and Mg atoms along dislocations in the cold-rolled alloys is responsible for the dissolution of the Guinier-Preston zones and precipitation of the Zn,Mg-containing particles at the relatively lower temperatures in comparison to classical mould-cast alloys. Microstructure observation proved that the Sc,Zr-content is mainly concentrated in randomlylocalized regions in the Al matrix and together with Zn and Mg in the particles at grain boundaries. The hardening effect after annealing above 280 • C was observed in the AlZnMgScZr alloy. Microhardness decrease at temperatures above ≈ 350 • C in the alloys without Sc and Zr is probably connected with faster recovery processes. Cold rolling has no significant effect on the apparent activation energy values of the Guinier-Preston zones dissolution and formation of the Zn,Mg-containing particles.

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Section: Introductionmentioning

confidence: 99%

Effect of Cold Rolling on Precipitation Processes in Al-Zn-Mg(-Sc-Zr) Alloy

et al. 2018

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“…Despite having some disagreements and obscurity about the arrangement and the types of the hardening phases in the alloys, the decomposition of supersaturated solid solution is in the consistency with two precipitation sequences, where η′(MgZn2)phase (hexagonal)/η(MgZn2)-phase (hexagonal) and T′(Al2Zn3Mg3)-phase (hexagonal)/T(Al2Zn3Mg3)-phase (cubic) occur [15,19,20]. The precipitation of the semi-coherent η′-and T′-phases usually cause the age-hardening of the materials in contrast to the incoherent η-and T-phases [19,20,[22][23][24][25][26][27]. Many authors use different designations for the early precipitation phases formed during the precipitation; (co-)clusters/Guinier-Preston (GP) zones of different types usually appear during ageing at temperatures lower than ~150 °C [19,20,25,[28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 86%

“…Taking into account the behavior of the constituent (especially Zn, Mg, and Cu) at temperatures from RT to ~80 °C [20] and the calculated contribution of the solute concentration to the resistivity of Al (e.g., References [1,54,55]), the resistivity development during natural ageing is mainly associated with the change of Zn and Mg concentrations in the Al matrix. In the first approximation it can be assumed that the (co-)clusters/GP zones are composed of Zn and Mg atoms in a ratio of: (a) 1:1; (b) 1:2, see e.g., References [10,15,17,19,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][56][57][58]]. If we assume this, then the resistivity Δρ changes in the HT + NA state (after natural ageing up to 3500 h), Δρ ≈ 8 nΩ•m, see Table 3, would correspond to the decrement of Zn-and Mg-concentration in the matrix: (a) ΔCZn,Mg ≈ 0.7 ± 0.1 at.%; (b) ΔCZn ≈ 0.8 ± 0.2 at.% and ΔCMg ≈ 0.4 ± 0.1 at.%.…”

Section: Natural Ageing Of the Heat-treated Alloysmentioning

confidence: 99%

“…The category of transformation line is changed with the content and composition of a particular element; the (non-)isothermal series of annealing steps are usually used [6,8,10,[17][18][19][20][21][22][23]. Despite having some disagreements and obscurity about the arrangement and the types of the hardening phases in the alloys, the decomposition of supersaturated solid solution is in the consistency with two precipitation sequences, where η′(MgZn2)phase (hexagonal)/η(MgZn2)-phase (hexagonal) and T′(Al2Zn3Mg3)-phase (hexagonal)/T(Al2Zn3Mg3)-phase (cubic) occur [15,19,20].…”

Section: Introductionmentioning

confidence: 99%

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Role of Small Addition of Sc and Zr in Clustering and Precipitation Phenomena Induced in AA7075

Vlach

Kodetová

Čı́žek

et al. 2020

Metals

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A detailed characterization of phase transformations in the heat-treated commercial 7075 aluminum alloys without/with low Sc–Zr addition was carried out. Mechanical and electrical properties, thermal and corrosion behavior were compared to the microstructure development. The eutectic phase consists of four parts: MgZn2 phase, Al2CuMg phase (S-phase), Al2Zn3Mg3 phase (T-phase), and primary λ-Al(Mn,Fe,Si) phase. Strengthening during non-isothermal (isochronal) annealing is caused by a combination of formation of the GP zones, η’-phase, T-phase and co-presence of the primary and secondary Al3(Sc,Zr)-phase particles. Positive influence on corrosion properties is owing to the addition of Sc–Zr. Positron annihilation showed an evolution of solute Zn,Mg-(co-)clusters into (precursors of) the GP zones in the course of natural ageing. The concentration of the (co-)clusters is slightly negatively affected by the low Sc–Zr addition. A combination of both precipitation sequences of the Al–Zn–Mg–Cu-based system was observed. The apparent activation energy values for dissolution/formation of the clusters/GP zones and for formation of the metastable η’-phase, stable T-phase and stable η-phase were calculated.

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“…Two decomposition sequences of AlZnMg(Cu) based alloys are known [6][7][8]: a) supersaturated solid solution (SSS) → solute clusters/Guinier-Preston (GP) zones → η´ phase (hexagonal structure) → η phase (MgZn2, hexagonal structure), b) SSS → solute clusters/GP zones → T´ phase (hexagonal Al2Zn3Mg3) → T phase (cubic Al2Zn3Mg3). The precipitation sequence could be more complicated, the formation of metastable precipitates depends on the alloy composition, artificial ageing temperature, ageing time, heat treatment etc.…”

Section: Introductionmentioning

confidence: 99%

THERMAL CHARACTERISTICS AND ELECTRICAL PROPERTIES OF HOT DEFORMED AA7075 ALLOYS WITH AND WITHOUT Sc, Zr ADDITIONS

Kodetová

Vlach

Leibner

et al. 2020

METAL 2020 Conference Proeedings

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In the present work AA7075 alloys with and without Sc, Zr addition after hot deformation were studied. Thermal responses of precipitation reactions of hot deformed alloys were studied by differential scanning calorimetry, the relative electrical resistivity changes were determined by DC four-point method. The interconnections of these two materials characteristics were presented. Thermal and electrical measurements were compared to microstructure development that was observed by scanning and transmission electron microscope. Two types of eutectic phase were proved at (sub)grain boundaries. In the AA7075-Sc,Zr alloy primary multilayer Al3(Sc,Zr) particles precipitated during casting and subsequent cooling. In the thermal curves one exothermic process at ~ 200 °C and the decrease of relative resistivity changes were observed. Apparent activation energy of this process was calculated using by Kissinger method as ~ 100 kJ/mol regardless Sc, Zr addition. Schematic timetemperature-transformation diagram of the exothermic process was done on the base of calorimetric measurements at different heating rates.

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Microstructure and mechanical properties of high strength Al–Zn–Mg–Cu alloys used for oil drill pipes

Cited by 30 publications

References 18 publications

Effect of Cold Rolling on Precipitation Processes in Al-Zn-Mg(-Sc-Zr) Alloy

Effect of Cold Rolling on Precipitation Processes in Al-Zn-Mg(-Sc-Zr) Alloy

Role of Small Addition of Sc and Zr in Clustering and Precipitation Phenomena Induced in AA7075

THERMAL CHARACTERISTICS AND ELECTRICAL PROPERTIES OF HOT DEFORMED AA7075 ALLOYS WITH AND WITHOUT Sc, Zr ADDITIONS

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