Innovative Alloys for High Pressure Die Casting 2009-01-0552
In October 2007, Fonderie 2a in cooperation with RENAULT TRUCKS Crash Calculation Department and Material Test Laboratory in Venissieux started a project aimed to study the mechanical behaviour in crash simulation and dynamic stress for different kinds of HPDC alloys utilised by Fonderie 2a for Renault’s engine and chassis parts. The main purpose was to value the best solution to: 1. avoid parts rupture and failure during operating lifetime; 2. valuate mechanical strength under regular stress; 3. valuate alloy’s behaviour simulating crash. Three different alloys was chosen for this aim: 1. SilR, a very strong and ductile alloy already used by Renault for most of its components, above all for “Ferrure sur cabine”, the main connecting part between cabin and chassis; 2. EN-AC 46000, a secondary Aluminium alloy, the most common alloy for HPDC process, whose main advantages are great fatigue strength, lower cost than primary alloy, ease of machining, against a congenital brittleness; 3. EN-AC 43100 T5, an aluminium alloy for sand casting, successfully used for the first time by Fonderie 2a for an HP die casted part. It was decided to build a die casting tool. This solution although more expensive allowed to realize specimens for different tests (tensile, strain and torsion), and acting on press parameters, to obtain them in different level of severity (according to standard ASTM E505) for porosity, cold fill and shrinkage, the most common defects in HP die casted parts. Results thus obtained permitted to evaluate the influence of these defects on mechanical behaviour and the deviation from reference value for each alloy. Test results showed great results as expected for Sil-R, whose mechanical properties (Rp0,2=200N/mm2, Rm=270 N/mm2, A%=5) made it the best solution when high performance in terms of ductility and high tensile strength, are required. The EN-AC 46000 confirmed its flexibility for different application on chassis and engine component. A great success came from 43100 T5, whose test results showed a better mechanical behaviour compared to value obtained by gravity casting (about 20% higher). All test results showed the great versatility of HPDC alloy and process for all components, and gave to Renault Crash Calculation Department all the informations required in engineering phase of their new parts, that fonderie2a will be proud to realize.