TALAT Lecture 50 Alloys and Properties 8 pages, 6 figures Basic Level prepared by Klaus Siegert and Manfred Kammerer, Institut für Umformtechnik, Universität Stuttgart Objectives: To provide a background on minium alloys suitable for impact extrusion To draw attention to raw material parameters which may affect the properties of parts Prerequisites: Basic knowledge about the formability of metals Background in mechanical engineering Date of Issue: 99 EAA European Aluminium Association
50 Alloys and Properties Table of Contents: 50 Alloys and Properties... 50.0 General Information on Alloys and Raw Materials... Aluminium Alloys for Impact Extrusion... Reference Ves for the Strength of Aluminium Alloy Impacts... Flow Curves and Fow Stresses... Raw Materials, Blanks and Slugs...5 Lubricants...5 Tool Life as a Function of Amounts of Lubricant...6 50.0 Literature:... 8 50.0 List of figures... 8 50.0 General Information on Alloys and Raw Materials Aluminium Alloys for Impact Extrusion Figure 50.0.0 lists the different types of minium alloys used for impact extrusion together with an evation considering different aspects. All minium alloys of the nonheattreatable and heattreatable types can be, especially when in their soft state. (See also DIN 7, part and DIN 75, part ). TALAT 50
Aluminium Alloys for Impact Extrusion Aluminium alloys for impact extrusion ) Merit ves, falling from to ; "" = not suitable ) Vation is valid for the original soft state ) S = weldability; L = suitability for brazing. Strength loss due to welding and soldering must be considered! Source: Aluminium Zentrale e.v. Designation Relative merit ves ) under various aspects according to DIN 7, p. Impact extrudability Decorative anodising Joining process ) Remarks ) and DIN 75, p. S L Pure and high purity minium (DIN 7, part) Al99.5 Al99.7 Al99.8 Al99.9 Nonheattreatable alloys (DIN 75, part ) AlMn AlRMg0.5 AlMg AlMg AlMgMn0. Heattreatable alloys (DIN 75, part ) AlMgSi0.5 AlMgSi AlZn.5Mg AlCuMg AlZnMgCu0.5 Main material for impacts Chemical brightening possible Chemical brightening possible Used only in artificially aged state Only for parts with heavy wall thickness which are used only in an aged state Aluminium Alloys for Impact Extrusion 50.0.0 In order to obtain high quality impacts, it is important to use materials which exhibit a homogeneous fibre structure or a uniform finegrained structure. A nonhomogeneous structure affects not only the chemical and physical properties of the impacts but also their form. An unsymmetrical grain structure can have a large effect on flow stress which in turn might lead to excentricity of the part, warpage or uneven distribution of wall thicknesses. Reference Ves for the Strength of Aluminium Alloy Impacts Figure 50.0.0 tables reference ves for the strength of minium alloy impacts. The minium alloys Al99,9, Al99,8. Al99,7 and Al99,5 are mainly used for manufacturing tubes and cans. The alloys AlMgSi0,5 and AlMgSi can be considered to be standard materials for impact extrusion. Care must be taken during the machining of the alloys AlZn,5Mg and AlZnMgCu0,5, since the emulsions used can lead to corrosion. TALAT 50
Reference Ves for the Strength of Impacts Attainable mechanical properties, not minimum ves ) By impact extruding directly after solution treatment and quenching ("freshly quenched" state) and then aging, 90% of the strength of the state "artificially aged" can be attained. Source: AluminiumZentrale e.v. Designation State Strength in N/mm² Elongation R m (σb) R p0. (σ0.) A 5 (%) Al99.5/ Al99 Al99.7/ Al99.8 Al99.9 AlMn AlRMg0.5 AlMg AlMg AlMgMn0. AlMgSi0.5 ) AlMgSi ) AlZn.5Mg AlCuMg AlZnMgCu0.5, imp. extr. artificially aged, imp. extr. artificially aged artificially aged naturally aged artificially aged 70 0 60 0 0 00 90 70 80 0 05 65 90 65 55 0 65 5 90 0 50 00 500 5 0 8 00 5 80 5 5 5 0 5 5 80 5 60 00 5 95 70 60 90 50 50 Reference Ves for the Strength of Impacts 50.0.0 0 6 0 0 0 0 0 0 0 0 7 Flow Curves and Fow Stresses Figure 50.0.0 shows flow curves and flow stresses of some minium alloys (at left) and the effect of state of heat treatment of AlMgSislugs on the flow behaviour (at right). Flow curves are needed for the calculation of forces for the impact extrusion process. For further flow curves, refer to the VDI guideline 500. Flow Curves and Flow Stresses Flow curves for various minium alloys at room temperature Flow stress, kf 600 N/mm² 00 00 0 State: ϕ = 5 x 0 s AlMg 0 True strain ϕ Source: J.Hardt AlCuMg AlMgSi(Mn) Al99.5 Flow stress, kf Flow stress as a function of heat treatment state of the slug 600 N/mm² 00 00 Artificially aged Naturally aged Hot worked Soft AlMgSi RT 0 0 True strain ϕ Source: H.G.Roczyn Flow Curves and Flow Stresses 50.0.0 TALAT 50
Raw Materials, Blanks and Slugs Figure 50.0.0 gives information regarding the manufacturing of slugs and blanks, their required surface condition and their properties. Cold rolled sheets and rods or tubes from which blanks and slugs are obtained by blanking or sawing, respectively, are standardised in DIN 75, part and DIN 5960. Round rods of pure minium or minium alloys are extruded with socalled multiple extrusion dies, i.e. three or four die openings are arranged around the centre of the die. In a final step these rods are cold drawn to size and final dimensions. Since the material is pressed through the multiple die not only from the centre portion of the billet but also from its outer areas, such round rods may exhibit different grain sizes in any one crosssection. As a result, impact extruded parts can warp in unexpected amounts and wall thicknesses may vary. Therefore, care should be exercised, that only singlestrand extruded rods are taken as base material for slugs and blanks. Raw Materials; Blanks and Slugs Manufacturing raw materials The raw material consists almost exclusively of stamped or sawed blanks and slugs available from extruders or stockists Surface condition of raw material Blank, ground, tumbled, blasted Requirements of raw material! The weight of blanks or slugs is allowed to vary only within a narrow tolerance range! Minimum clearance between slugs and die: 0. to 0.mm! Maximum tolerance for round slugs and blanks is h (larger deviations in diameter lead to positioning errors)! A uniform grain size. Varying grain size can lead to variations in dimensions Source: Schlosser; Brix Raw Materials; Blanks and Slugs 50.0.0 Lubricants Figure 50.0.05 lists the different lubricants used and the methods of applying them. Because of environmental considerations, watersoluble lubricants like alkalinen soaps and liquid lubricants based on oil are being increasingly used. Zinc stearate and zinc behenate have nowadays to compete with Lubrimet GTT (Sapilub Ltd. Co. Wangen, Zurich) based on paraffin without chlorinated solvents and heavy metal soaps with optimal solubility in water, Glisapal SM55 (Nußbaum Co., Matzingen), a watersoluble, solventfree, powdery lubricant based on alkaline soaps, not suitable for anneal degreasing and solvent cleaning, TALAT 50 5
and liquid lubricants based on oil, like Bonderlube VP 0/5 (Chemetall Co., Frankfurt), with sulphur compounds, but free from chloroparaffins and metal organic compounds or Multipress 99 (Zeller and Gmelin Co., Eislingen), a fully synthetic oil. In individual cases, coating layers serving as carriers for lubricants (minium, phosphate) are used. Lubricants used Lubricants! Zinc stearate and zinc behenate (insoluble in water)! Alkaline soaps (water soluble)! Liquid lubricants based on oil (water soluble) Methods of applying lubricants! Spraying! Coating! Sprinkling, powdering! Dipping! Tumbling Source: D.Schlosser Lubricants 50.0.05 Tool Life as a Function of Amounts of Lubricant Figure 50.0.06 illustrates the influence of amount of lubricant used (g/m²) on tool life. As can be clearly seen, too little or too much lubrication reduces the tool life. If the lubricant used is insufficient, cold welding can occur between tool and workpiece. If too much lubricant is used, then the lubricant accumulation leads to defects in contour replication and to lubricant indentations in the tool. In these cases, the tool has to be cleaned very often. The surface roughness of slugs and blanks has an effect on the tool life. Experiments have shown that smooth slugs reduce the life of tools because the smooth slug surface offers hardly any cavities and pits in which the lubricant can be anchored. TALAT 50 6
Tool Life as a Function of Amounts of Lubricant Tool life Cold welding failure optimum Contour defects failure Source: D.Schlosser Relative lubricant amount in g/ m² Tool Life and Lubricant Amounts 50.0.06 TALAT 50 7
50.0 Literature: ) F.Ostermann: Technische Kaltfließpreßteile aus Aluminium. In seminar volume "Gestalten und Fertigen von technischen Fließpreßteilen aus Aluminium", Institut für Umformtechnik, Universität Stuttgart, 5.6. June, 99 ) D.Schlosser: Einflußgrößen auf das Fließpressen von Aluminium und Aluminiumlegierungen und ihre Auswirkung auf die Weiter und Fertigbearbeitung der fließgepreßten Rohteile. In seminar volume "Gestalten und Fertigen von technischen Fließpreßteilen aus Aluminium", Institut für Umformtechnik, Universität Stuttgart, 5.6. June, 99 ) D.Brix: Kaltfließpressen von Leichtmetall Qualität und Wirtschaftlichkeit. Draht 975/5, p. 69 ) VDIRichtlinie 8: Kaltfließpressen von Stählen und Nichteisenmetallen, Grundlagen, part. BeuthVerlag, Berlin, 970 5) AluminiumZentrale e.v., Report No. 9 "Aluminium für technische Fließpreßteile", Düsseldorf, 98 50.0 List of figures Figure No. Figure Title (Overhead) 50.0.0 Aluminium Alloys for Impact Extrusion 50.0.0 Reference Ves for the Strength of Impacts 50.0.0 Flow Curves and Flow Stresses 50.0.0 Raw Materials; Blanks and Slugs 50.0.05 Lubricants 50.0.06 Tool Life and Lubricant Amounts TALAT 50 8