Effects of Zn Addition and Aging Condition on Serrated Flow in Al-Mg Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 483-488 ◽  
Author(s):  
Katsushi Matsumoto ◽  
Yasuhiro Aruga ◽  
Hidemasa Tsuneishi ◽  
Hikaru Iwai ◽  
Masataka Mizuno ◽  
...  
Keyword(s):  
Artificial Aging ◽  
Flow Behavior ◽  
Natural Aging ◽  
Atom Probe ◽  
Mg Alloys ◽  
Scanning Calorimetry ◽  
Serrated Flow ◽  
Zn Addition ◽  
Al Mg Alloys ◽  
Zn Alloys

The serrated flow phenomena in Al-Mg alloys with and without Zn were investigated after aging on several conditions, focusing on the role of precipitates. Al-6mass%Mg-0~3mass%Zn alloys were solution treated at 753~803K, quenched, and then aged at room temperature. Further artificial aging at 323~573K for 86.4ks was performed for some of them after natural aging for 2.6Ms. The serrated flow behavior was evaluated by tensile test. Microstructure was characterized by differential scanning calorimetry, transmission electron microscopy, atom probe tomography, and positron annihilation lifetime spectroscopy. The increase in the amount of Zn addition and the natural aging time lead to a delayed onset of serrated flow. The artificial aging at higher temperatures after natural aging, on the other hand, decreases the onset strain. A large number of small coherent Zn-Mg clusters are formed during natural aging in the Al-Mg-Zn alloys, which are transformed to the larger incoherent meta-stable precipitates during subsequent artificial aging. These results suggest that the mechanism of interfering with serrated flow is related to the vacancy trapping effect, which is enhanced by the coherent clusters.

Zn/Cu regulated critical strain and serrated flow behavior in Al–Mg alloys

2020 ◽  
Vol 795 ◽  
pp. 139991
Author(s):  
Yingxin Geng ◽  
Di Zhang ◽  
Jishan Zhang ◽  
Linzhong Zhuang
Keyword(s):  
Critical Strain ◽  
Flow Behavior ◽  
Mg Alloys ◽  
Serrated Flow ◽  
Al Mg Alloys

scholarly journals Serrated Flow and Enhanced Ductility in Coarse-Grained Al-Mg Alloys

2010 ◽  
Vol 42 (4) ◽  
pp. 1028-1037 ◽  
Author(s):  
Ehab Samuel ◽  
John J. Jonas ◽  
Fawzy H. Samuel
Keyword(s):  
Mg Alloys ◽  
Coarse Grained ◽  
Serrated Flow ◽  
Al Mg Alloys

Solute concentration dependence of strength and plastic instabilities in Al-Mg alloys

2005 ◽  
Vol 20 (2) ◽  
pp. 331-337 ◽  
Author(s):  
Gy. Horváth ◽  
N.Q. Chinh ◽  
J. Lendvai
Keyword(s):  
Dislocation Line ◽  
Solute Concentration ◽  
Mg Alloys ◽  
Dynamic Strain ◽  
Solute Content ◽  
Serrated Flow ◽  
Indentation Tests ◽  
Power Law Function ◽  
Chatelier Effect ◽  
Al Mg Alloys

Characteristics of the dynamic strain aging (DSA) in the Portevin-Le Chatelier effect are experimentally investigated by dynamic indentation tests and numerically analyzed by using literature models. Experimental results obtained on Al–Mg alloys show that the occurrence and development of the plastic instabilities—serrated indentation—depend strongly on the solute content. During dynamic microindentation tests the amplitude of microhardness drops—similarly to the global hardness—and is changing as a power law function of Mg solute content with an exponent of 2/3. It has been shown that the term describing the effect of DSA in serrated flow is not proportional but rather a power expression of the local solute concentration, Cs, on the dislocation line with the exponent of 1/2. Together with this, the kinetics of solute segregation during DSA is controlled by the pipe diffusion.

Nano-Scale Clusters Formed in the Early Stage of Phase Decomposition of Al-Mg-Si Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 357-360 ◽  
Author(s):  
Shoichi Hirosawa ◽  
Tatsuo Sato
Keyword(s):  
Early Stage ◽  
Sheet Material ◽  
Three Dimensional ◽  
Natural Aging ◽  
Aging Treatment ◽  
Atom Probe ◽  
Phase Decomposition ◽  
Aging Behavior ◽  
Scanning Calorimetry ◽  
Nano Scale

The formation of nano-scale clusters (nanoclusters) prior to the precipitation of the strengthening b” phase significantly influences two-step aging behavior of Al-Mg-Si alloys. In this work, the existence of two kinds of nanoclusters has been verified in the early stage of phase decomposition by differential scanning calorimetry (DSC) and three-dimensional atom probe (3DAP). Pre-aging treatment at 373K before natural aging was also found to form preferentially one of the two nanoclusters, resulting in the remarkable restoration of age-hardenability at paint-bake temperatures. Such microstructural control by means of optimized heat-treatments; i.e. nanocluster assist processing (NCAP), possesses great potential for enabling Al-Mg-Si alloys to be used more widely as a body-sheet material of automobiles.

Effect of the Long Natural Aging on the Precipitation Sequence in Al-Mg-Si Alloy

2014 ◽  
Vol 893 ◽  
pp. 375-380 ◽  
Author(s):  
Zakaria Boumerzoug ◽  
Ines Hamdi
Keyword(s):  
Differential Scanning Calorimetry ◽  
Artificial Aging ◽  
Natural Aging ◽  
Precipitation Sequence ◽  
Precipitation Behavior ◽  
Scanning Calorimetry ◽  
Hardening Mechanism ◽  
Negative Effect

In this study, the effect of the long natural aging on the precipitation sequence of Al-Mg-Si alloy was investigated by differential scanning calorimetry and hardness examinations. This investigation revealed that the natural aging has a negative effect on the artificial aging. The reason behind the influence of natural aging on precipitation behavior of the Al-Mg-Si alloy is assumed to be the formation of clusters and G.P. zone during natural aging. The hardening mechanism during artificial aging was explained.

Pre-Aging and Maturing Effects on the Precipitation Hardening of an Al-Mg-Si Alloy

2010 ◽  
Vol 297-301 ◽  
pp. 68-73
Author(s):  
T. Abid ◽  
A. Boubertakh ◽  
S. Hamamda
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Artificial Aging ◽  
Precipitation Hardening ◽  
Natural Aging ◽  
Undesirable Effect ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Later Phase ◽  
Scanning Electron

The effect of pre-aging and maturing at room temperature on the hardening response of an Al-Mg-Si alloy is investigated using differential scanning calorimetry (DSC), hardness measurements (Hv) and scanning electron microscopy (SEM).Two experimental conditions are examined. First, natural aging for different times (3 weeks and 1 month) followed by artificial aging at 180°C as a function of time. Second, pre-aging at temperatures in the range 75-100°C followed by artificial aging at 180°C after natural aging for the same periods. The present results indicate that the effect of the pre-aging just after the heating and quenching is used in order to correct the undesirable effect of aging at room temperature. However, during the artificial aging, the alloy hardening becomes faster. Aged samples which have already undergone pre-aging and maturing reveal the precipitation of ''phase. This later phase has the highest hardness value.

scholarly journals Effect of Auto-Tuning on Serrated Flow Behavior

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 845 ◽  
Author(s):  
S.M.A.K. Mohammed ◽  
D.L. Chen
Keyword(s):  
Mild Steel ◽  
Mechanical Response ◽  
Flow Behavior ◽  
Adaptive Controller ◽  
Tensile Tests ◽  
Hydraulic Testing ◽  
Al Alloys ◽  
Mg Alloys ◽  
Serrated Flow ◽  
Auto Tuning

The mechanical response of a servo-hydraulic testing system is affected by the stiffness of test specimens. An adaptive controller helps in auto-tuning the system by setting the optimal proportional-integral-derivative values for the subsequent test as the stiffness changes. This paper presents the effect of auto-tuning of various channels on the flow response of several commercial Al and Mg alloys and a mild steel. Strain-controlled monotonic tensile tests were performed at a given strain rate of 1 × 10−4 s−1 after auto-tuning of position, load, and strain channels in different combinations. Serrated flow or Portevin–Le Chatelier effect was observed in the Al alloys after auto-tuning of either position channel only or position and load channels. However, the serrations of Al alloys were shielded after further auto-tuning of strain channel. The stress-strain curves of Mg alloys and mild steel were observed to be basically free of serrations under any combinations of auto-tuning, which confirms that the serrated flow is a property of specific materials rather than a machine system noise.

Minimizing serrated flow in Al-Mg alloys by electroplasticity

2019 ◽  
Vol 35 (6) ◽  
pp. 1108-1112 ◽  
Author(s):  
Hui Xu ◽  
Xuebing Liu ◽  
Di Zhang ◽  
Xinfang Zhang
Keyword(s):  
Mg Alloys ◽  
Serrated Flow ◽  
Al Mg Alloys
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