Creep Behavior of Al-Si Die-Cast Alloys

2004 ◽  
Vol 126 (4) ◽  
pp. 378-383 ◽  
Author(s):  
Tim Jaglinski ◽  
Roderic Lakes
Keyword(s):  
Primary Silicon ◽  
Constant Load ◽  
Primary Creep ◽  
Silicon Phase ◽  
Creep Tests ◽  
Engine Operation ◽  
Casting Alloys ◽  
Die Cast ◽  
Cast Alloys ◽  
Creep Regime

Commercial, aluminum die-cast alloys are subject to long-term stresses leading to viscoelastic material responses resulting in inefficient engine operation and failure. Constant load creep tests were conducted on aluminum die-casting alloys: B-390, eutectic Al-Si and a 17% Si-Al alloys. Rupture occurred in the primary creep regime, with the eutectic alloy having the longest times to failure. Primary creep was modeled by Jt=A+Btn with A, B, and n dependent on stress. Poor creep performance is linked to the brittle fracture of the primary silicon phase as well as other casting defects.

Viscoplasticity Based on Total Strain. The Modelling of Creep With Special Considerations of Initial Strain and Aging

1979 ◽  
Vol 101 (4) ◽  
pp. 380-386 ◽  
Author(s):  
Erhard Krempl
Keyword(s):  
Strain Relaxation ◽  
Stress Test ◽  
Time Derivative ◽  
Constant Load ◽  
Primary Creep ◽  
True Stress ◽  
Initial Strain ◽  
304 Stainless Steel ◽  
Creep Tests ◽  
Creep Curves

A previously proposed theory is specialized for the uniaxial state of stress and its prediction for creep and relaxation is analyzed in detail. Constant true stress and constant load creep tests are simulated in the presence and absence of thermal aging together with the constant strain relaxation test. The signs of the creep rate and its time derivative as well as the relaxation rate and its time derivative are introduced as criteria. The constant load creep test can reproduce the normal creep curves and nonclassical creep curves (ε˙ > 0; ε¨ > 0 for all ε and for σ0 > 0). The capabilities of the constant true stress test are limited to primary creep if the work-hardening slope is positive. When aging is introduced almost any creep curve can be reproduced in both tests. The importance of initial strain is discussed and demonstrated by room temperature creep tests on Type 304 Stainless Steel. It is suggested that the initial strains together with the creep curves be reported in the future. Poisson’s ratio in creep needs to be measured and tests are proposed which will enable a quantitative assessment of aging.

scholarly journals Observations of the creep of polar firn

2021 ◽  
pp. 1-19
Author(s):  
Yuan Li ◽  
Ian Baker
Keyword(s):  
Total Porosity ◽  
Constant Load ◽  
Primary Creep ◽  
Secondary Creep ◽  
Micro Ct ◽  
Creep Tests ◽  
Thin Sections ◽  
Compressive Stresses ◽  
Optical Images ◽  
Before And After

Abstract Constant-load creep tests were performed at −10°C at various compressive stresses from 0.05 to 0.75 MPa on specimens taken every 10 m along a firn core extracted at Summit, Greenland in June 2017. The microstructures before and after creep testing were examined using both X-ray microtomography (micro-CT) and optical images from thin sections. An Andrade-like equation was used to describe the primary creep behavior and yielded the time exponent k of 0.17–0.76. The onset of secondary creep occurred at strains of ~0.5–3% but was sometimes not observed at all in shallow firn specimens and at stresses ⩽0.43 MPa even for strain up to 32%. For the 50–80 m firn crept at stresses ⩾0.55 MPa, secondary creep occurred at strains of 2.6 ± 0.28%, and the stress exponent, n, in Glen's law, was found to range from 4.1 to 4.6, similar to those observed for fully dense ice. Micro-CT observations of crept specimens showed that in most cases, the specific surface area, the total porosity and the structure model index decreased, while the structure thickness increased with increasing density. These microstructural characteristics are consistent with the densification of the firn. Optical images from thin sections showed that recrystallization occurred in some specimens that had undergone secondary creep.

Effects of Bismuth on the Microstructure and Mechanical Properties of AlSi9Cu3(Fe) Die Casting Alloys

2013 ◽  
Vol 765 ◽  
pp. 59-63 ◽  
Author(s):  
Stefano Ferraro ◽  
Giulio Timelli ◽  
Alberto Fabrizi
Keyword(s):  
Mechanical Properties ◽  
Trace Element ◽  
Die Casting ◽  
Eutectic Structure ◽  
Al Alloys ◽  
Casting Alloys ◽  
Microstructure And Mechanical Properties ◽  
Die Cast ◽  
Foundry Alloys ◽  
Cast Alloys

In secondary die cast Al alloys, Bismuth is generally considered an impurity element and present as a trace element in commercial foundry alloys. In the present work, the influence of different Bi content on the microstructure and mechanical properties of a commercial die cast AlSi9Cu3(Fe) alloy is investigated. The Bi level ranges between 0.015 and 0.3 wt.%. The results show that the presence of Bi seems to not produce significant changes in the microstructure and mechanical properties. Fine Bi-rich compounds are observed in the die cast alloys and they are mainly distributed in the interdendritic regions and along grain boundaries. TEM investigations revealed a complex Bi-Bi2Mg3eutectic structure, which presents mainly rod-type and blocky morphology.

Long-Term Creep Modeling of Modified 9Cr-1Mo Steel for a Sodium Cooled Fast Reactor

2010 ◽  
Author(s):  
Woo-Gon Kim ◽  
Jae-Young Park ◽  
Sung-Ho Kim ◽  
Chan-Bock Lee
Keyword(s):  
Constant Load ◽  
Primary Creep ◽  
Least Square ◽  
Creep Data ◽  
Creep Tests ◽  
Omega Method ◽  
Creep Curves ◽  
The Individual ◽  
Term Creep

This paper focused on long-term creep modeling for describing total creep curves of up to rupture for modified 9Cr-1Mo steel (G91). Creep data was obtained by a series of constant-load creep tests at 600°C. Three modified constitutive equations of modified power-law method (MPM), modified theta method (MTM) and modified omega method (MOM), described as a sum of a decaying primary creep and an accelerating tertiary creep, were proposed. A nonlinear least square fitting (NLSF) analysis was carried out on the basis of the creep data so that they provide the best fit to experimental data in optimizing parameter constants of the individual equation. Results of the NLSF analysis showed that in the lower stress regions of 160MPa (σ/σys<0.65), the MTM matched well with the experimental creep data compared with the MPM and MOM, but that in the higher stress regions of 160MPa (σ/σy > 0.65), the MPM revealed better agreement than the MTM and MOM. It was found that the MTM was superior in the modeling of long-term creep curves to the MPM and MOM. Long-term creep curves for the G91 steel were numerically modeled and its creep life was predicted by the MTM.

Microstructure of die-cast alloys Mg–Zn–Al(–Ca): a study by electron microscopy and small-angle neutron scattering

2003 ◽  
Vol 94 (5) ◽  
pp. 564-571 ◽  
Author(s):  
Michael Vogel ◽  
Oliver Kraft ◽  
Peter Staron ◽  
Helmut Clemens ◽  
Rainer Rauh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Die Cast ◽  
Cast Alloys

ZA-12

Alloy Digest ◽  
1990 ◽  
Vol 39 (5) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Shear Strength ◽  
Die Casting ◽  
Casting Alloys ◽  
Die Cast ◽  
The Family ◽  
Aluminum Smelting ◽  
Cold Chamber ◽  
Intermediate Member

Abstract ZA-12 is the intermediate member of the family of three ZA die-casting alloys. Its melting point, solidification range and recommended casting-temperature range are greater than those of ZA-8. (See Alloy Digest Zn-48, January 1990). Due to these factors, ZA-12 must be die cast in cold chamber die-casting machines like conventional aluminum die-casting alloys. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive and shear strength as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as forming, machining, and surface treatment. Filing Code: Zn-49. Producer or source: Aluminum Smelting and Refining Company Inc.. See also Alloy Digest Zn-31, September 1977.

Influence of Sr and TiB on the Microstructure and Eutectic Temperature of Al-12Si Die-Cast Alloys

2017 ◽  
Vol 27 (10) ◽  
pp. 544-551
Author(s):  
Yong-Lak Choi ◽  
◽  
Seon-Hwa Kim ◽  
Dong-Hyun Kim ◽  
Sang-Il Yoon ◽  
...  
Keyword(s):  
Eutectic Temperature ◽  
Die Cast ◽  
Cast Alloys

scholarly journals Microstructural evolution during high-temperature tensile creep at 1,500°C of a MoSiBTiC alloy

2020 ◽  
Vol 39 (1) ◽  
pp. 136-145 ◽  
Author(s):  
Sojiro Uemura ◽  
Shiho Yamamoto Kamata ◽  
Kyosuke Yoshimi ◽  
Sadahiro Tsurekawa
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Grain Boundary Sliding ◽  
Primary Creep ◽  
Tensile Creep ◽  
Tertiary Creep ◽  
Continuous Dynamic Recrystallization ◽  
Continuous Dynamic ◽  
Creep Regime

AbstractMicrostructural evolution in the TiC-reinforced Mo–Si–B-based alloy during tensile creep deformation at 1,500°C and 137 MPa was investigated via scanning electron microscope-backscattered electron diffraction (SEM-EBSD) observations. The creep curve of this alloy displayed no clear steady state but was dominated by the tertiary creep regime. The grain size of the Moss phase increased in the primary creep regime. However, the grain size of the Moss phase was found to remarkably decrease to <10 µm with increasing creep strain in the tertiary creep regime. The EBSD observations revealed that the refinement of the Moss phase occurred by continuous dynamic recrystallization including the transformation of low-angle grain boundaries to high-angle grain boundaries. Accordingly, the deformation of this alloy is most likely to be governed by the grain boundary sliding and the rearrangement of Moss grains such as superplasticity in the tertiary creep regime. In addition, the refinement of the Moss grains surrounding large plate-like T2 grains caused the rotation of their surfaces parallel to the loading axis and consequently the cavitation preferentially occurred at the interphases between the end of the rotated T2 grains and the Moss grains.

scholarly journals The development of low-temperature heat-treatable high-pressure die-cast Al–Mg–Fe–Mn alloys with Zn

2021 ◽  
Author(s):  
Xiangzhen Zhu ◽  
Fuchu Liu ◽  
Shihao Wang ◽  
Shouxun Ji
Keyword(s):  
Heat Treatment ◽  
Low Temperature ◽  
Mechanical Test ◽  
Equilibrium Phase ◽  
Solution Temperature ◽  
Tem Analysis ◽  
Die Cast ◽  
Zn Concentration ◽  
Temperature Heat ◽  
Cast Alloys

AbstractIn the present work, a novel low-temperature heat-treatable recycled die-cast Al–Mg alloy was developed by adding Zn into non-heat-treatable Al–5Mg–1.5Fe–0.5Mn alloy. The results showed that Zn additions resulted in the formation of equilibrium phase T-Mg32(Al, Zn)49 under as-cast condition, which can be dissolved into the α-Al matrix at a relatively low solution temperature (430 °C) and thus set the base for the low-temperature heat treatment. The mechanical test results indicated that Zn additions had a smooth liner improvement in the strength of all as-cast alloys and T6-state alloys with 1% and 2% Zn as its concentration increased but resulted in a sharp improvement on the strength of T6-state alloy when Zn concentration increased from 2 to 3%. TEM analysis revealed that the precipitate in T6-state Al–5Mg–1.5Fe–0.5Mn–3Zn alloy is η′ phase, rather than the widely reported T″ or T′ phase in other Al–Mg–Zn alloys with approximately same Mg and Zn concentrations. After the optimized low-temperature T6 heat treatment (solution at 430 °C for 60 min and ageing at 120 °C for 16 h), the Al–5Mg–1.5Fe–0.5Mn–3Zn alloy exhibits the yield strength of 321 MPa, ultimate tensile strength of 445 MPa and elongation of 6.2%.

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