Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C23/00—Alloys based on magnesium
  • C22C23/06—Alloys based on magnesium with a rare earth metal as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon

Definitions

• the present invention relates to the field of metalworking, and more particularly to magnesium alloys.
• magnesium-based alloys for the same applications. Indeed, these are known on the one hand for their lower density and secondly because they are likely to benefit from better heat resistance. However, not all magnesium alloys are satisfactory. For example, the known alloy series AZ31, AZ61 or AZ80 and ZK reveal behaviors similar to aluminum alloys and thus do not meet the expressed need. New molded magnesium alloys have appeared in recent years and are destined for the same field of application, but molding generates high hazard rates, of the order of 15 to 30%. Defects such as porosity or shrinkage must be taken into account when dimensioning parts. This reduces the benefit of their job.
• the applicant has set itself the objective of producing a magnesium alloy part, for the reduction of mass that it provides with respect to aluminum in particular, but whose metallurgical and dimensional stabilities at the operating temperatures of the part are sufficient. not to require thickening mechanically stressed areas. Indeed, such thickening is often necessary to take into account the loss of characteristics due to the thermal aging of the material that constitutes it.
• the invention achieves these objectives with a method of manufacturing a magnesium alloy part comprising a step of forging a block of said alloy followed by a heat treatment, characterized in that the alloy is an alloy 85% magnesium based foundry comprising by weight:
• foundry alloy is that provided by the company
• Magnesium Elektron Limited (under the reference Elektron 21) with standardized designation EV31A and whose more precise composition is as follows.
• the magnesium alloy comprises: 0.2 to 0.5% Zinc, 2.6 to 3.1% Neodymium, 1.0 to 1.7% Gadolinium, and is saturated with Zirconium. This product is defined by the claims of the patent application WO 2005/035811.
• the forging temperature is between 420 and 430 ° C. and the plastic deformation is carried out at a slow speed, in particular at a speed corresponding to a speed of movement of the forging ram less than 40 mm / sec.
• the forging plastic deformation is carried out by stamping in one or more steps.
• the plastic deformation is carried out by spinning or rolling.
• the initial block is molded and more particularly molded block is wrought beforehand before stamping.
• the forging is followed by a heat treatment with a dissolution step, a quenching step and a tempering step at a temperature of between 200 ° C. and 250 ° C.
• FIG. 1 shows a block of foundry alloy in its initial form before forging and in its form after roughing.
• Figure 2 is an example of a stamping installation.
• a delivery device for the machining of metal blanks comprises two flat piles, possibly comprising a recess housing.
• a piece is placed on the lower pile, the two flat piles being pressed against each other, by a press, to ensure the backflow of the billet, which takes the form, corresponding to the housing between the two flat piles.
• Several backflow operations are usually necessary to obtain the billet usable in stamping. Heats of plots are possible between the different operations of repression.
• Milling is then carried out in one or more steps; for example, a first blanking die step makes it possible to obtain a first form approaching the definitive form. Then we proceed to precision stamping on a press to obtain the piece to the final form. It is observed that this final shape may be machined if necessary to obtain the part ready for use.
• An example of installation 3 is shown in FIG. 2.
• the matrices, upper 5a, lower 5b, are flat heaps that make it possible to obtain the shape at the stage considered.
• the blank is heated in the same way before the precision stamping step.
• the stamping tools are preheated and maintained in temperature during the manufacturing process.
• the speed of deformation of the part corresponding to the speed of movement of the slide of the stamping machine is less than 40 mm / sec, preferably between 10 and 30 mm / s, the target speed is 20 mm / s.
• the temperature range of income between 200 0 C and 225 ° C is optimized to obtain better characteristics in the case of operation at room temperature.
• the temperature range of income between 225 ° C and 250 0 C is optimized to obtain better characteristics in the case of operation at a temperature above 180 0 C. Tests were carried out so as to be able to compare the mechanical properties of the forged alloy with a molded alloy of the prior art AS7G06T1R2 which is a reference for aeronautics.
• the tensile strength Rm in Mpa and the yield strength Rpo were measured. 2 .

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Forging (AREA)

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• 2006
  • 2006-07-20 FR FR0653053A patent/FR2904005B1/fr active Active
• 2007
  • 2007-07-19 CA CA2659041A patent/CA2659041C/fr active Active
  • 2007-07-19 EP EP07823307.9A patent/EP2074237B1/de active Active
  • 2007-07-19 CN CN200780027450.8A patent/CN101517117B/zh active Active
  • 2007-07-19 WO PCT/FR2007/001245 patent/WO2008009825A2/fr not_active Ceased
  • 2007-07-19 BR BRPI0714451A patent/BRPI0714451B1/pt active IP Right Grant
  • 2007-07-19 US US12/374,548 patent/US8142578B2/en active Active

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