Magnesium alloys have the lowest density of all commercial alloys and this makes them attractive for the automotive industry. The heavy envelopes enclose data for a given class of material. In this work, we aimed at further improving the creep resistance by the addition of other alloying elements. Such insights have helped us develop creep resistant alloys using finescale precipitates and dispersion of hard particles to obstruct dislocation motion in the parent matrix 15,16,17,18,19,20,21. Oct 05, 2018 as mentioned above, in the past decades, a number of creepresistant cast magnesium alloys have been developed and commercially used in industries 1, 9, 10. Development of creep resistant mgalsr alloys springerlink. Magnesium alloys, with a lower density than steel or aluminum, have the potential to reduce the mass of automotive components. However, new alloys with improved creep resistance must be developed before mg can be used for high temperature powertrain applications. Pdf development of creepresistant magnesium casting alloys. Magnesium alloy creep resistance strontium content good castability good creep resistance these keywords were added by machine and not by the authors. The creep response of mgalca alloy containing barium diemag422 was compared to that of commercially available creep resistant magnesium alloys ae42 and mri230d. Pdf creep resistant magnesium alloys for powertrain applications. Pdf the relationship between microstructure and creep. Creep resistant magnesium alloys for powertrain applications.
Magnesium based alloys have been extensively developed for use as structural materials in the automotive, aircraft and aerospace industries. The diagonal contours show the longitudinal wave velocity. Mg alloys for high temperature applications require considerations on several properties in conjunction with the creep strength. Evaluation of magnesium diecasting alloys for elevated temperature applications.
Developed for engine blocks and transmissions, the acx alloys have at least 40% greater tensile and 25% greater compressive creep resistance than ae42, and. Current development of creepresistant magnesium cast alloys. Developed for engine blocks and transmissions, the acx alloys have at least 40% greater tensile and 25% greater compressive creep resistance than ae42, and corrosion. Unfortunately, it is difficult to achieve an adequate combination of properties and, in fact, most of the new alloys can only partially meet the required performance. This paper introduces major properties of the developed alloys, which are necessary for practical applications in transportation vehicle parts. Ca alloys and reported a good creep resistance of the alloys. Oct 25, 2014 creep resistant mg diecasting alloy, which exhibits superior creep resistance to az91 at temperatures up to 423 k 150 c. Development of highly creep resistant magnesium alloys. Ep8531a1 high strength and creep resistant magnesium. New aspects of temperature behavior of aj52x, creep resistant. Improving the properties of magnesium alloys for high. Creep behavior of aj62 magnesiumaluminumstrontium alloy. Exceptional increase in the creep life of magnesium rareearth.
Minor zn addition to mg alloys improves the creep resistance of mggdbased alloys via the formation of new zncontaining precipitate phases. The alloy has been found to exhibit more favorable castability and creep resistance than comparative magnesium based alloys. This process is experimental and the keywords may be updated as the learning algorithm improves. Microstructure, tensile properties, and creep resistance suming zhu, mark a. Highly creep resistant magnesium alloys containing sc, rare earths gd, ce, nd, y and manganese exhibit a considerably higher corrosion resistance than high. The development of creep resistant alloys over the past 20 years is discussed, ranging from the we series developed early in the 1980s and which represents the present state of the art to mgsc and mggd ternary alloys that show an improvement in creep resistance of two orders of magnitude. Criteria for developing castable, creepresistant aluminum. Tests conducted at a single temperature or stress do not. Limited range of alloys available poor creep resistance due to fine grainsize cast microstructure limited castability and high cost of creep resistant mgalre alloys heat treatment not possible unsuitable for welding 2.
High strength and creep resistant magnesium alloys. Request pdf creep resistance in magnesium alloys mg creep resistant alloys have seen increased interest in the 1980s and 90s due to the weight reduction objectives of automotive companies. Creep and corrosion properties of the extruded magnesium alloy. Firstprinciples study of typical precipitates in creep. Exceptional increase in the creep life of magnesium rare. For weightsensitive applications, the low density of al alloys allows for materials with high specific strengths. Influence of rare earth elements on creep resistance of highpressure diecast magnesium rare earth alloys serge gavras, suming zhu, mark a. This is attributed to the high internal stress typical of an hcp structure having only two independent basal slip systems.
The magnesium alloy that has received most attention is az91 mg9al1zn, wt. Creep mechanisms of creep resistant magnesium diecasting alloys are studied. Development of creepresistant magnesium casting alloys for high temperature automotive applications l. Poole, wj and kainer, ku, eds 2012 proceedings of the 9th international conference on magnesium alloy and their applications, july 812, 2012, vancouver, bc, canada. Improving the performance of magnesium alloys for automotive. Table 3 presents, for comparison, the secondary creep rate for the same alloys tested at 300c and at a stress of. Effects of alloying elements of the creep resistance of. These alloys are up ten times more resistant to creep than we 43 t6 and are comparable with other highperformance alloys. Nov 23, 2001 the development of highly creep resistant magnesium alloys is presented. So far, many precipitates have been found in creep resistant magnesium alloys that play a very important role in optimizing the microstructure and mechanical properties. The alloy systems studied are binary mgsc, mggd and ternary mgscmn and quaternary mgsccemn, mggdscmn and mgyscmn.
Pdf creep resistant magnesium alloys for powertrain. The precipitates are mggd and very effective at high gd concentrations. The synergetic effects of microstructural changes are. Since the 90s, a number of new creep resistant magnesium alloy systems have been investigated and. In accordance with the teachings of the present invention, a family of magnesium based alloys with improved creep resistance and castability includes between about 3% and 10% aluminum, between about 0. Development of creepresistant magnesium alloys for. A family of lowcost, creep resistant magnesium alloys has been developed. Creep strength of magnesiumbased alloys springerlink. For a similar composition, the mgnd alloy is the most creep resistant whilst the mgla alloy is the least creep resistant, with the mgce alloy being in between. Mg was observed to have large subgrains within the grain and very. Increased applications of magnesium alloys for elevated temperature service require the development of lowcost alloys with good creep resistance and sufficiently high strength.
Development of mgal based alloys with rare earth re and alkaline earth element additions has led to the automotive application of mg6al2sr aj62 alloy in the bmw engine block and the mg4al4re ae44. Sep 20, 2000 summary this paper describes the latest developments in optimizing the creep resistance of systems based on mg. Us7041179b2 high strength creep resistant magnesium alloys. Pdf newly developed magnesium alloys for powertrain.
The results suggest that the creep resistance of magnesium alloys is determined by the weakest aggregate andor phase in the alloy, viz. Creep resistance creep resistance of magnesium alloys has been studied extensively by the australian research organisation. Pdf creep resistant magnesium alloys are candidate materials for automotive powertrain applications. Gibson several families of magnesium diecasting alloys have been developed to operate at the elevated temperatures experienced in automotive. Increase in creep resistance of mg al alloys is achieved by. Despite the interest in these materials, and the extensivedevelopment of creep resistant magnesium alloys based, most recently, on the mgsc and mggd ternary systems 3. The hightemperature creep resistance of magnesium alloys was discussed, with special reference to mgal and mgy alloys. The mechanicalpropertiesofmgreznalloysatlowandelevated. Development of high temperature creep resistant alloys. Development of creepresistant magnesium casting alloys for.
Click here for relevant document pdf file metallurgical background to the development of creep resistant alloys magnesium alloys, being the lightest structural metallic materials, are very attractive in automotive and. Introduction to magnesium alloys asm international. Creep resistant magnesium alloys are candidate materials for automotive powertrain applications. Creep behaviour under compressive stresses of calcium. The microstructure and creep properties of ascast mgsnsial. Evaluation of magnesium diecasting alloys for elevated. There are also solid solution hardening effects of the ca addition to the alloys. There is interest in magnesium zinccalcium alloys for fig. Comparative thermal conductivity the high thermal conductivity of aj52x increases the ability to transfer heat inside the component, compared to ae42 and other creep resistant mg alloys. An evaluation of the creep characteristics of an az91. Mg creep resistant alloys have seen increased interest in the 1980s and 90s due to the weight reduction objectives of automotive companies. There have been attempts since in the 70s to develop creep resistant magnesium diecasting alloys for automotive applications such as automatictransmission. At temperatures above 100c they undergo excessive creep deformation even at low stress levels.
However, compared with other structural cast mg alloys, such as the az series alloys, the market of creepresistant mg alloys is relatively small. Pdf evaluation of magnesium diecasting alloys for elevated. The matrix microstructure may influence the creep properties of the composite. Abstract creep resistant magnesium alloys are candidate materials for automotive powertrain applications. These alloys, containing aluminum, calcium, and strontium are designated as acx alloys. Feb 15, 2002 these alloys are up ten times more resistant to creep than we 43 t6 and are comparable with other highperformance alloys. Development of high temperature creep resistant alloys magnesium alloys and their applications wiley online library. Moreover, al alloys are naturally oxidation resistant due to an extremely stable passivating protective oxide layer. Pdf the influence of zn additions on the microstructure and. Mgal solidsolution alloys are superior to almg solidsolution alloys in terms of creep resistance. The creep behaviour of several alloys is shown in figure 1. Newly developed magnesium alloys for powertrain applications. Review on research and development of heat resistant magnesium. The creep resistance of squeeze cast az 91 and qe 22 magnesium alloys reinforced with 20 vol.
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