Documents

aluminium.pdf

Description
1 Aluminum Alloys Wrought and Cast alloys designation and heat treatment Source of figure ASM HANDBOOK Vol. 2 and 4 - 1991 ALUMINUM – Properties, Physical Metallurgy and Phase Diagrams - Vol. 1 - 1967 2010 – Prof. G. Ubertalli General Characteristics The melting temperature is 660°C. The melting temperature is 660°C. The Young modulus is 70 GPa. The mass volume is 2,700 Kg/m 3 . It has good thermal and electrical conductivity. It is corrosion “resistant”. It is corrosion “resistant”.
Categories
Published
of 25
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Related Documents
Share
Transcript
  1  Aluminum Alloys Wrought and Cast alloys designation and heat treatment Source of figureASM HANDBOOK Vol. 2 and 4 -1991ALUMINUM –Properties, Physical Metallurgy and Phase Diagrams -Vol. 1 -1967 2010 –Prof. G. Ubertalli General Characteristics  ° .   The Young modulus is 70 GPa.   The mass volume is 2,700 Kg/m 3 .   It has good thermal and electrical conductivity. “ ”     s corros on res s an .   Some alloys are hardenable by solution heat treating. 2010 –Prof. G. Ubertalli  2 Wrought Aluminum Alloys Series Alloy family 2XXX  Al-Cu 3XXX  Al-Mn 4XXX  Al-Si 5XXX  Al-Mg 2010 –Prof. G. Ubertalli 6XXX  Al-Mg-Si 7XXX  Al-Zn 8XXX Other (ex. Al-Li) Hardening Mechanisms  mechanism of metallic alloys, to understand and know the influence of mechanical and heat treatments to which these alloys has undergone. 1.STRAIN HARDENING . 3.SECOND PHASE PARTICLES4.SOLID SOLUTION 2010 –Prof. G. Ubertalli  3 Strain Hardening Temper Temper Temper TemperDescriptionDescriptionDescriptionDescriptionFas-fabricatedOannealed, recrystallizedH1strain hardened (H12, H14, H16, H18)H2strain hardened and partially annealed (H22, H24, H26,H28)H3strain hardened and stabilized (H32, H34, H36, H38) H321strain hardened during fabricationH323, H343strain hardened during fabrication 2010 –Prof. G. Ubertalli Interaction Dislocation / Particles In the micrograph the interaction, between dislocations themselves and between dislocations and particles in the matrix is represented. This interaction shows itself like loops and helices associated with manganese containing dispersed particles in 2024-T4 alloy (40,000X). 2010 –Prof. G. Ubertalli  4 The metallurgy of heat treatment Even if the term “heat treatments” includes all those operations that refer toheating and cooling of a component, in this paragraph we refer mainly to the heattreatments effected on the final product, such as annealing, solution heating,quenching and stress relieving. It can be used both for plastic deformation and for casting alloys. Obviously, each of these types has its own characteristics andpro ems concernng ea rea men .  Soften the alloy to improve workability and formability.  Increase strength and produce particular mechanical properties that areassociated with a specific final temper.  Stabilise mechanical or physical properties or resistance to corrosion, and avoidchanges that normally would occur in time or at high temperatures.  Ensure dimensional stability during service, especially for parts that operate at.  Relive residual stresses induced by differential deformation or non-uniformcooling after casting, quenching, welding or forming operations.When the term is applied to aluminium alloys, its use is frequently restricted tospecific operations employed to increase strength and hardness of theprecipitation-hardenable wrought and cast alloys (see further on). 2010 –Prof. G. Ubertalli Sometimes treatments are effected in order to decrease the strength or residual stressesinduced by plastic deformation, while other treatments are effected to modify the distributionand the morphology of the microstructure. In aluminium and its alloys transformations of lattice structure in the field of solid solution will not happen. However, through the control of the solution heat treating and the following precipitation of particles the yield strength couldbe increased with factors of 5 - 6 in the case of alloys for heat treatments.The variation of solubility of the alloying elements with temperature is the main factor that could be used inheat treatments, namely to influence the distribution of the alloying elements itself. Also if thep ase agram oes no s ow e me as a e p ases a are orme a re a vey owtemperatures (age hardening), that are responsible for the strengthening effects, they pointout the conditions under which the reaction could proceed in solid phase (composition,temperature and initial structure). The precipitation rate is also influenced by the diffusion rateof each solute element in the alloy.The relationship temperature-solubility in solid phase and the temperature-diffusion rate varywidely for the different types of solute and the effects of maintaining a specific temperaturecould be different for the different solutes. Many aluminium alloys contain one or moreelements that have different solubility and diffusion coefficient. Some elements precipitate at, ,magnesium, silicon or zinc and the combination of these elements). As described in ternaryor quaternary phase diagrams, in many cases complex interactions occur, with precipitationof intermetallic phases containing two or more solutes other than aluminium. Therefore eachcommercial alloy has its own characteristics that require a good control of the operations of heat treatment effected on the ingots, on the intermediate products and during themanufacturing process. In order to do this, a right combinations of time and temperaturemust be used during the final operation of heat treatment. 2009 –Prof. G. Ubertalli
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks