Download or read book The Effect of Quenching Rate on Aging Response and Mechanical Properties of Al 7wt Si 0 3Wt Mg Casting Alloy written by Stiliana Raynova and published by . This book was released on 2002 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Response of 7000 Series Alloys to Hot Stamping written by Kaab Omer and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hot stamping, or die quenching (DQ), of 7000-series aluminum alloys is a metal forming process in which a blank is heated (solutionized) and then quenched and formed in cold tooling. The formed part is then subjected to an artificial aging treatment to reach a targeted final strength (temper). The work presented herein addresses several aspects of the die quenching process chain for two 7000-series aluminum sheet alloys, AA7075 and a developmental alloy referred to as AA7xxx. The thesis addresses: (i) identification of forming process and artificial aging parameters needed to achieve high strength structural properties within an automotive die quenching paradigm; (ii) characterization of high temperature constitutive and heat transfer properties required to accurately simulate the die quenching process; and (iii) development of a model of the work hardening response of die quenched AA7075 as a function of the extent of artificial aging. The effect of the solutionizing duration, the transfer time between the furnace and die, and the in- die quench rate on the subsequent aging response were examined for both alloys. Experiments revealed that both alloys require a solutionizing time of 8 min at 470 °C. For AA7075, a transfer time of up to 6 s (furnace to die) was deemed to be acceptable since this time duration does not appear to result in premature precipitation. For AA7xxx, a transfer time of up to 15 s is acceptable. AA7075 required a minimum quench rate of 56 °C/s, whereas AA7xxx requires only 27 °C/s. Variations in aging treatments following die quenching were also considered in order to obtain desirable yield and ultimate tensile strength properties while accounting for the paint bake cycle (PBC) and its effect on artificial aging response. It was determined that AA7075 could achieve strength properties similar to those a T6 temper if it was aged for 8h at 121 °C followed by a PBC (30 min at 177 °C). AA7xxx could achieve T6-like properties if aged for 3h at 100 °C followed by a PBC and T76-like properties if aged for 4h at 100 °C, followed by a PBC. A detailed characterization of the constitutive behaviour and heat transfer characteristics of these alloys under DQ conditions was performed. Of particular note, this characterization was performed at elevated temperatures while the material was in a solutionized condition. The acquired properties consisted of: (i) the temperature and strain rate dependent stress-strain properties; (ii) the yield surface, and (iii) the heat transfer coefficient (HTC) of both alloys. The stress-strain properties were obtained by subjecting tensile specimens to a temperature-time cycle resembling the DQ process. A novel technique was devised in which the cross-sectional area of the tensile specimens were measured using stereoscopic digital image correlation (DIC) technique. A Barlat Yld2000 yield surface was calibrated using anisotropic properties obtained from shear and tensile tests. The HTC was obtained as a function of contact pressure by performing a series of instrumented quenching experiments in which the temperatures of the blank and die were measured as a function of time. These temperature-time curves were processed using Fourier's law and Newton's cooling law to calculate HTC. The acquired elevated temperature constitutive properties and heat transfer coefficients were input to a finite element model of die quenched deep drawn cups. The load-displacement and earring profile results from the experiments were shown to match well with the predicted results from the model. The final step in the DQ process chain was also considered in terms of the final or in-service mechanical properties of die quenched and artificially aged components. A micro-mechanics based model was developed to predict the stress-strain response and work hardening rate of AA7075 as a function of the aging treatment applied. The micromechanics model accounts for precipitate-dislocation interaction during deformation following aging and was validated for a range of multi-step aging treatments. Tensile tests were performed considering tempers ranging from as-quenched up to the peak aged condition, and the model was shown to accurately predict flow stress over the entire range of aging treatments considered.

Download or read book THE EFFECT OF SOLIDIFICATION RATE AND SOLUTIONIZING QUENCH RATE ON THE MECHANICAL PROPERTIES AND HARDENING RESPONSE OF ALUMINUM ALLOYS written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : A comparative study of five aluminum alloys was performed to characterize the effect of solidification rate and quench rate on casting microstructure and properties. The alloys were cast in the geometry for Jominy End Quench (JEQ) testing, so as to take advantage of the JEQ test's ability to give data on multiple quench rates in a single sample and illustrate the quench sensitivity of an alloy. While the Jominy End Quench test has been used in aluminum alloys, the effects of solidification rates have not been assessed in depth. The work done by other studies has either focused on a single alloy across multiple solidification rates, or on multiple alloys using a single solidification rate. To this end, three molds were created: a sand mold, a semi-permanent mold and a permanent mold, with the intent of casting JEQ bars out of multiple aluminum alloys for direct comparison. The tensile strength, hardness, porosity, and electrical conductivity were assessed, in an attempt to compare the quench sensitivities of the samples. This study will provide a starting point for more in-depth analyses of the alloys, i.e. the kinetics of precipitation strengthening over a range of length scales (cooling rates).

Download or read book Influence of Quench Rate on the Artificial Ageing Response of an Al 8Si 0 4Mg Cast Alloy written by and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimisation of the Heat Treatment Cycles of CSIR Semi solid Metal Processed Al 7Si Mg Alloys A356 7 written by Heinrich Moller and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Conventional casting alloys Al-7Si-Mg A356/7 contain between 6.5 and 7.5% Si, together with 0.25-0.7% Mg and are used for critical castings in the automotive and aerospace industries. These alloys are also the most popular alloys used for semi-solid metal (SSM) forming due to good castability and fluidity imparted by the large volumes of the Al-Si eutectic. Despite their industrial importance, there is a lack of detailed research work revealing precipitate micro- and nanostructural evolution during aging of these alloys compared with the Al-Mg-Si 6000 series wrought alloys. This study characterises the heat treatment response of SSM-processed Al-7Si-Mg alloys in comparison with conventionally liquid cast alloys (investment casting and gravity die casting). It is shown that, provided that the maximum quantity of the alloy's Mg is placed into solid solution during solution treatment, and that the alloy's Fe content is within specification, the response to age hardening of Al-7Si-Mg alloys is independent of the processing technique used. The nanostructural evolution of Al- 7Si-Mg alloys after artificial aging with and without natural pre-aging has been characterized using transmission electron microscopy and atom probe tomography and correlated with hardness and mechanical tensile properties. The number densities and Mg:Si ratios of solute clusters, GP zones and ;?-needles were determined. The heat treatment response of SSM-processed casting alloys A356/7 alloys are also compared with SSM-processed Al-Mg-Si 6000 series wrought alloys, with the advantage of having similar globular microstructures. The high Si-content of the casting alloys compared to the wrought alloys offers several advantages, including a faster artificial aging response (shorter T6 aging cycles), higher strength for comparable Mg contents and less sensitivity to prior natural aging on peak strength. Finally, an age-hardening model was developed for the Al-7Si-Mg alloys, including a method of incorporating the effects of changes in Mg-content on the aging curves.

Download or read book The Influence of Quenching and Aging on Fracture Toughness of the Al Zn Mg Cu Alloy 7449 written by J. Robinson and published by . This book was released on 2014 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation characterises the fracture toughness of the very high strength Aluminium alloy 7449. This Al-Zn-Mg-Cu alloy is heat treatable and relies on rapid quenching from the solution heat treatment temperature to promote subsequent artificial aging. While the influence of quench paths on strength is well understood and can be predicted using techniques like quench factor analysis, the influence of quench rate on fracture toughness is more challenging. The rate of quenching can influence the fracture toughness through complex precipitation reactions occurring during cooling. The precipitate locations dictate the magnitude of the detrimental effect on the fracture toughness. In this investigation, the fracture toughness of 7449 in two product forms was measured using compact tension specimens cut from forged blocks and rolled plate. These plane strain (KIC) results were also augmented with Charpy impact tests. Various quench conditions were investigated, including water at three different temperatures and poly oxyethylene glycol (PAG) in two concentrations. The influence of standard and novel aging procedures including retrogression and reaging was also determined. The combinations of strength and toughness have been related to the prevailing microstructural condition. Fracture toughness magnitudes were found to vary most significantly with rapidity of cooling from the solution treatment temperature, with the subsequent aging treatments having a much smaller effect.

Download or read book Quench Rate and Aging Effects in Aluminum zinc magnesium copper Aluminum Alloys written by Donald Scott MacKenzie and published by . This book was released on 2000 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Varying Quench Rates and Heating Rates on the Aging Response of an Aluminum Powder Alloy written by Walter M. Griffith and published by . This book was released on 1977 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research examines the effect of varying quench rates and the effect of varying heating rates on the aging response of powder aluminum MA87 alloy. The effect of a six-day room temperature pre-age was also considered. The results obtained are compared with results of similar research on 7075 ingot product and supplemented with electron microscopy. The results indicate little difference in terms of hardness, in the response of MA87 and 7075. This suggests that the quench sensitivity of both alloys is similar and is attributable to the same mechanism. (Author).

Download or read book Influence of Processing Variables and Aluminum Content on the Microstructure and Mechanical Properties of Cast Mg Al Alloys written by Blair Edward Carlson and published by . This book was released on 1997 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Methodology to Predict the Effects of Quench Rates on Mechanical Properties of Cast Aluminum Alloys written by and published by . This book was released on 2006 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Precipitate Hardening Treatment on Microstructure and Mechanical Properties of Cast Aluminum Silicon Alloy A356 written by Benjunior Bindamin and published by . This book was released on 2012 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this work was to study the influence of the precipitate hardening treatment of the A356 aluminum silicon sand cast alloy. The experiment process was separated into three parts which was foundry laboratory, material laboratory, and inspection. In the foundry laboratory, the cast alloys was prepared by sand casting process and was melted in a diesel furnace. In the material laboratory, the casting was then treated with precipitate hardening treatment and followed by machining. The inspection was done to observe microstructure, tensile properties and hardness properties. The effect of the solution heat treatment and artificial aging holding time on the microstructure, tensile properties, and hardness properties of the alloy was analyzed. Three specimens were heat treated with a solution treatment at a same temperature of 540°C, was quenched in room temperature water followed by artificial aging at a same temperature of 170°C. The different parameters were holding times which were solution at 2 hours and aging 2 hours, solution at 2 hours and aging 6 hours, solution 6 hours and aging 6 hours. The microstructure were investigated and tested by optical microscope, tension test and Rockwell hardness test respectively. The result found was at 2 hours solution of 540 °C homogenization and saturation of magnesium and silicon in Į(Al) phase, spheroid of eutectic Si phase occurred. After solution treatment, 2 hours artificial aging at 170 °C produced hardening precipitates. Samples treated at 6 hours solution and 6 hours artificial aging achieved even higher tensile strength and hardness. The increased of holding time for solution and artificial aging increased precipitate hardening.

Download or read book THE INFLUENCE OF PRIOR NATURAL AGING ON ARTIFICIAL AGE HARDENING IN AL MG SI ALLOYS written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Aluminum alloys of the 6000 series (Al-Mg-Si) are among the most prevalent and established structural materials in the world. Their use dates back decades, and currently they are crucial to the construction and transportation industries. One of the primary reasons for this is heat-treatability, i.e. the ability to control strength and ductility relationships with a relatively low temperature artificial aging treatment. Although multiple aluminum alloys can be employed for this purpose (e.g. 2000, 7000 series), Al-Mg-Si alloys are capable of achieving a highly attractive combination of moderate to high strength (sometimes > 350 MPa UTS), high ductility (>20% elongation), and excellent corrosion resistance, extrudability, weldability, and surface finish. 350 MPa UTS), high ductility (>20% elongation), and excellent corrosion resistance, extrudability, weldability, and surface finish.20% elongation), and excellent corrosion resistance, extrudability, weldability, and surface finish. The largest unknown in the world of 6000 series alloys today is a result of natural aging (NA) prior to artificial aging (AA), and the rather mysterious impacts on strengthening precipitation and hardenability that are produced. The origins of these impacts involve complex interactions between solute atoms, solute-clusters, and vacancies, which ultimately influence the kinetics and thermodynamics of precipitation. Although this has been the topic of extensive research in recent years, the actual mechanisms responsible are still very controversial. This dissertation will focus on the effects of prior natural aging on artificial age hardening response under a wide range of compositional and heat treatment conditions. Ultimately it will be shown that the behavior of naturally aged solute-clusters during artificial aging is dependent on alloy composition, and furthermore that these clusters are directly responsible for the changes in strengthening precipitation and performance. General background to the topic and an overview of the experimental methods are described in Chapters 1-2. The most important chapters of this dissertation are Chapters 3-4, which focus on the influence of prior NA in high strength Al-Mg-Si alloys after a water quench from the solutionization temperature. In Chapter 3, a compositional (Mg/Si) dependence of the NA effect is identified, and proposed to due to a corresponding dependence of NA cluster stability during artificial aging. In Chapter 4, the actions of NA clusters at AA temperatures are investigated with atom probe tomography, and the relative thermal stabilities suggested in Chapter 3 are proven. The rest of the dissertation includes studies focused on the NA effect under different compositional and heat-treatment conditions, using the previous cluster thermal stability findings to aid in analysis (Chapter 5). Mechanical property characterization of key experimental conditions is performed in Chapter 6, and good agreement with the previous results is found. Finally, key conclusions, implications, and suggested future work is summarized in Chapter 7 & 8.

Download or read book The Effects of Two Stage Aging on the Microstructure and Mechanical Properties of the New Al Si Cu Mg Alloy written by and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Small Additions of Silver on the Mechanical Properties of Aluminum Casting Alloys written by R. B. Miclot and published by . This book was released on 1968 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents significant test results showing that 0.3% silver additions to melts of certain aluminum casting alloys, 40E and Precedent 71A, increase the yield and tensile strengths without large loss of ductility. Yield strength improves 80% and tensile strength 45% in test-size castings of silver treated 40E alloy, after solution-precipitation treatment; yield and tensile strengths increase more than 13% each, in machined specimens from end-chilled plates. A one week delay between solution treatment and artificial aging of the standard 40E alloy improves the yield and tensile strengths more than 30% each, but no additional improvement occurs in the silver-treated alloy. After artificial aging only, test-size castings from the silver treated alloy increase more than 25% in yield and 10% in tensile strength; machined specimens from plates improve more than 15% in yield and 5% in tensile strength. Only marginal gain in yield strength occurs after natural aging for 40 days. Remelting of the alloy does not destroy the beneficial effects of silver additions. Silver improves the yield strength 5 to 10% in Precedent 71A alloy after solution-precipitation treatment. (Author).

Download or read book Predicting the Response of Aluminum Casting Alloys to Heat Treatment written by Chang Kai Wu and published by . This book was released on 2012 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The objective of this research was to develop and verify a mathematical model and the necessary material database that allow predicting the physical and material property changes that occur in aluminum casting alloys in response to precipitation-hardening heat treatment. The model accounts for all three steps of the typical precipitation hardening heat treatment; i.e., the solutionizing, quenching, and aging steps; and it allows predicting the local hardness and tensile strength, and the local residual stresses, distortion and dimensional changes that develop in the cast component during each step of the heat treatment process. The model uses commercially available finite element software and an extensive database that was developed specifically for the aluminum alloy under consideration namely A356.2 casting alloy. The database includes the mechanical, physical, and thermal properties of the alloy all as functions of temperature. The model predictions were compared to measurements made on commercial cast components that were heat treated according to standard heat treatment protocols and the model predictions were found to be in good agreement with the measurements.

Download or read book Effect of Ageing on the Hardness and Tensile Properties of Aluminium Alloy 7001 with Special Reference to the Influence of Delay Time Between the Quenching and Ageing Treatments written by J. H. Cole and published by . This book was released on 1978 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Age Hardening Response of Thermomechanically Processed Al Mg Li Alloys written by William F. Ferris and published by . This book was released on 1987 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Four Al-Mg-Li alloys of composition (weight percent) in the ranges 6-8% Mg, 0.5-2% Li, and 0.15-0.25% Zr were hot forged and warm rolled (thermo-mechanically processed) to achieve a microstructure suitable for superplasticity. They were then subjected to age-hardening studies at temperatures indicated by concurrent differential scanning calorimetry research. Optical and transmission electron microscopy techniques were used to relate microstructure to mechanical properties. Only the 6%Mg-2%Li alloy showed significant age hardening response, however, concurrent research demonstrated excellent superplastic response in the 6%Mg-1%Li and 8%Mg-1%Li alloys. Keywords: Thermomechanically, Processed, Superplasticity, Age Hardening Studies, Aluminum alloys, Magnesium alloys, Lithium alloys.