Aluminum Alloys, Processing and Characterization: Properties of Aluminium Alloys I
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Dmitry Eskin, Brunel University
Tuesday 2:00 PM
February 25, 2020
Room: 1A
Location: San Diego Convention Ctr
Session Chair: Samuel Wagstaff, Novelis
2:00 PM Introductory Comments
2:05 PM
High Cycle Fatigue Properties of the Zr-modified Al-Si-Cu-Mg Alloy at Elevated Temperatures: Shouxun Ji1; Guangyu Liu1; Paul Blake2; 1Brunel University London; 2Jaguar Land Rover
The Al-Si-Cu-Mg alloy with 0.14wt%Zr addition has been studied against the counterparts of commercially used EN-AC-42000 (Al7Si0.5Cu) baseline alloy for the effect of Zr on the high cycle fatigue (HCF) properties at elevated temperatures. It was found that the fatigue life was significantly improved by 8-10 times at the high stress amplitude of 140 MPa in the Zr-modified alloy at all different temperatures. The fatigue strength coefficient of the baseline alloy was 574.9, 589.8, and 514.8 MPa at 150, 200, and 250 oC, respectively, which was greatly increased to 1412.3, 620.1, and 821.6 MPa for the Zr-modified alloy. The improved fatigue properties could be mainly ascribed to: (1) the refined microstructure, with α-Al grain size decreasing from 335 to 253 μm and the secondary dendrite arm spacing (SDAS) dropping from 39 to 28 μm; (2) the reduced porosity; and (3) the additional precipitates strengthening effect by the Al-Si-Zr-Ti dispersoids.
2:30 PM
Effect of Mo on Elevated-temperature Low-cycle Fatigue Behavior of Al-Si 356 Cast Alloy: Sinan Chen1; Kun Liu1; X Grant Chen1; 1University of Quebec at Chicoutimi
Components of diesel engines are often subjected to cyclic loading at elevated temperature during operation, which may cause their fatal fatigue failure. In this study, elevated-temperature low-cycle fatigue (LCF) tests were conducted at 300°C on Al-Si 356 cast alloys with Mo addition. Various strain amplitudes of 0.1%, 0.2%, 0.4% and 0.6% was applied. Results showed that a high volume of finer dispersoids formed with addition of Mo. Compared with the base alloy free of Mo, a higher fatigue strength but reduced plastic strain at all studied strain amplitudes was obtained in the alloy containing Mo. Smaller fatigue striation spacing was observed in Mo-containing alloy, indicating its better fatigue crack propagation resistance. However, the total LCF cycle at 300°C in the alloy with Mo was lightly decreased due to the less sustainable of crack to the final rupture. Fatigue parameters were calculated from test data for fatigue life estimation.
2:55 PM
State Parameter-based Simulation of Temperature- and Strain Rate Dependent Flow Curves of Al-alloys: Bernhard Viernstein1; Philipp Schumacher2; Benjamin Milkereit2; Ernst Kozeschnik1; 1Institute of Materials Science and Technology, TU Wien; 2University of Rostock
When simulating the material behavior during thermo-mechanical processes, the understanding of the microstructure evolution is fundamental. Therefore, state parameter-based models are utilized to describe physical effects such as work hardening, precipitation hardening, solid solution hardening and cross core diffusion. Using the thermo-kinetic software package MatCalc, temperature- and strain rate dependent flow curves of compression- and tensile tests are successfully simulated. The theoretical background of the underlying physical models and the influence of alloying elements on the work hardening and cross core diffusion behavior are discussed. Various Al-alloys are investigated and the experimentally obtained flow curves are evaluated in terms of initial strain hardening rate, initial yield stress and saturation stress. Especially the effect of Mg is dominant while investigating Al-alloys, based on its ability to diffuse from the compression side to the tension side of the dislocations core, leading to additional barriers for the dislocation movement.
3:20 PM
Coarsening-resistance of a Severely Deformed Al-0.2wt% Sc Alloy: Yan Huang1; 1Brunel University London
Second-phase Al3Sc particles in Al-Sc alloys play an important role in several aspects of material performance. These include grain refinement, strengthening, stabilizing microstructure and increasing recrystallization temperature. The present work was conducted to investigate the stability of Al3Sc particles in an Al-0.25Sc alloy at room temperature in comparison to that of Al2Cu precipitates in an Al-Cu alloy. Microstructural examination and hardness tests showed that the Al3Sc particles were coarsening resistant with substantially higher stability than Al2Cu and the hardness of the Al-0.25Sc alloy remained almost constant while an apparent hardness drop was observed for the Al-Cu alloy.
3:45 PM Break
4:00 PM Cancelled
The Effect of Modified Strain-induced Melt Activation (Modified SIMA) Process on the Microstructure and Mechanical Properties of Al-7Si Alloy: Chandan Choudhary1; Durbadal Mandal1; Kanai Sahoo2; 1National Institute of Technology, Durgapur; 2CSIR-National Metallurgical Laboratory, Jamshedpur
Al-Si alloys have been consistently drawing attention of the technocrats due to its numerous favourable properties.Conventionally cast alloys, the primary morphology is, in general, dendritic and,suffers from several defects such as hot tear, porosity, interdendritic shrinkage etc. If these dendritic networks can be broken by any means, then the castings produced will be free from above mentioned defects and at the same time will posses higher mechanical properties. Semi solid metal (SSM) processing is one of the methods of producing near spheroidal morphology. Among the various SSM processing, Strain Induced Melt Activation (SIMA) is convenient for producing plates. In this study, we have attempted to alter the dendritic structure of Al–7Si alloy by SIMA process which reduces the size and morphology primary α-Al grains. The strength of as cast Al-7Si is 117 MPa with El 16% whereas, SIMA processed Al-7Si sample shows the strength of 204 MPa with El 32%.
4:25 PM
Effect of Mg on Flow Behavior of Al-Mg Alloys and Its Constitutive Modelling Using Finite Element Analysis: Shahin Ahmad1; Vilas Tathavadkar1; Alankar Alankar2; K. Narasimhan2; 1Aditya Birla Science & Technology Co. Pvt. Ltd.; 2Indian Institute of Technology, Bombay
Al-Mg alloys are one of the most widely used materials for automotive and marine applications due to its relatively higher strength and superior corrosion properties in marine environment. However, with increasing magnesium content in these alloys, the engineering workability decreases. The flow behavior of AA5052 and AA5083 alloys were studied by performing the tensile test along the rolling direction at various temperatures and strain rates, ranging from RT- 400°C and 0.001 - 1 s-1 respectively, using Gleeble® 3800 thermomechanical simulator to study the effect of Mg content on various state variables. These experiments were used to determine material model coefficients at different test conditions for both the alloys. Johnson–Cook (JC) material model was used to describe the material behavior with finite element simulations in commercial finite element analysis package ABAQUS™. The simulation results based on JC model depicted a close agreement with the experimental results.
4:50 PM
Influence of Thermal Treatment and Design Parameters on the Fatigue Life of Automotive Control Arm Fabricated from A357 Semi-solid Alloy: Mohamed Attia1; Khaled Ragab1; Mohamed Bouazara1; X Grant Chen1; 1Universite du Quebec a Chicoutimi
Suspension control arm is considered one of the most significant automotive components as a mechanical part that is responsible of linking the wheels of the vehicle to the chassis. The materials and design of such components are the matter of research that mainly focus on the enhancement of its performance considering safety and cost factors. Fatigue failure is considered a common problem that faces these parts due to variable dynamic loading. Currently, the research trend is to manufacture this part from aluminum A357 semi-solid alloys, produced by Rheocasting SEED technique, due to its high strength-to-weight ratio and ductility. This work aims at investigating an innovative thermal treatment and design parameters to enhance the fatigue life of the automotive control arm. The results revealed that the interrupted thermal aging as well as the modified trussed design show superior quality and performance concerning the fatigue life.