StaCast Project: New standards on defects classification and on mechanical properties of casting alloys

Transcription

1 StaCast Project: New standards on defects classification and on mechanical properties of casting alloys E. Fiorese, F. Bonollo, G. Timelli, G. Kral L. Arnberg, A.C.R. Adamane Department of Management and Engineering University of Padua Norwegian University of Science and Technology October 2013 Elena Fiorese 1/22 TARGETS OF THE STACAST PROJECT (1) Investigate on the role of Aluminium alloys for the future of EU foundry industry (2) Drawing up of a CEN Technical Report on defects and imperfections classification in Al alloy cast products (3) Drawing up of a CEN Technical Report on mechanical potential of Al foundry alloys (4) Writing of engineering rules for the mechanical design of Al alloy castings 2/22

2 PARTNERS Department of Management and Engineering University of Padua (Italy) University of Applied Sciences of Aalen (Germany) Norwegian University of Science and Technology (Norway) Italian Association of Metallurgy (Italy) Assomet Services (Italy) Federation of Aluminium Consumers in Europe (Brussel) 3/22 SURVEY ON EU FOUNDRY INDUSTRY Foundry questionnaire Company profile General data on production Used CEN Standards Need for new EU standards Defect analysis and used inspection techniques Frequency of defects Structure of questionnaire project.org 4/22

3 ANSWERS FROM FOUNDRIES 5/22 ANSWERS FROM OTHER COMPANIES roughly 80 answers from foundries and other companies almost 3% of EU Al alloy foundries (i.e. 58 on ~ 2000) tons/year production of the StaCast foundries (i.e. the 12.5% of the overall EU production) 6/22

4 MOST USED ALLOYS AND PROCESSES Most used alloys EN AB EN AB EN AB EN AB GDC/LPDC 31% HPDC 69% 7/22 DEFECTS FREQUENCY Frequency of defects as estimated by HPDC foundries: gas/air porosity and metal die interaction Frequency of defects as estimated by GDC/LPDC foundries: gas/air porosity and shrinkage 8/22

5 NEED FOR NEW CEN STANDARDS Medium high interest for new CEN Standards on defects classification, mechanical properties and guidelines 9/22 NEW DEFECTS CLASSIFICATION Previous classifications Cocks approach position Campbell approach metallurgical origin NADCA approach morphology NEW 3 LEVELS APPROACH Path through a new classification I) morphology/location of defects (internal, external, geometrical) II) metallurgical origin of defects (e.g. gaseous porosity, solidification shrinkage, etc.) III) specific type of defects (the same metallurgical phenomenon may generate various defects) «Handbook of defects in High Pressure Die Casting» E. Gariboldi, F. Bonollo, P. Parona 10/22

6 I level II level III level Internal defects Shrinkage defects Gas related defects Filling related defects Undesired phases Thermal contraction defects Macro and interdendritic shrinkage, layer porosity Air, hydrogen, vapour, lubricant entrapment porosity Joint, lamination, cold shot Inclusion, undesired structure Crack, hot tear I level II level III level Surface defects Shrinkage defects Gas related defects Filling related defects Undesired phases Thermal contraction defects Metal die interaction defects Sink Blister, pinhole Joint and vortex, lamination, cold shot Surface deposit, contamination or inclusion Crack, hot tear Erosion, soldering, thermal fatigue, ejection mark, corrosion of the die I level II level III level Geometrical defects Lack of material Excess of material Out of tolerance Incomplete casting Flash Deformed part 11/22 DEVELOPMENT OF 1 PRE NORMATIVE DOCUMENT Definition, image Morphology, dimensions, inspection techniques Metallurgical origin, frequency 12/22

7 DEVELOPMENT OF 1 PRE NORMATIVE DOCUMENT GAS RELATED DEFECTS approximately spherical cavities characterized by smooth surface due to entrapment of air, hydrogen, vapour or lubricant dimensions in the range 10 µm 0.5 mm radiographic, ultrasonic inspections and metallographic tests. SHRINKAGE DEFECTS due to the volume contraction during solidification wide solidification range and low temperature gradients macro shrinkage > 0.5 mm and inter dendritic shrinkage in the range µm radiographic, ultrasonic inspections and metallographic tests. FILLING RELATED DEFECTS microstructural discontinuity due to the interaction between melt flows at different temperature variable dimensions for the joint and in the range mm for the cold shot metallographic tests. Air porosity Macro shrinkage Cold shot 13/22 DEVELOPMENT OF 1 PRE NORMATIVE DOCUMENT UNDESIRED PHASES non metallic phases due to the interaction with environment dimensions > 0.1 mm radiographic, ultrasonic inspections and metallographic tests. THERMAL CONTRACTION DEFECTS geometrical discontinuity due to the casting contraction constrained by die or already solidified material dimensions between 10 µm and various mm ultrasonic inspections and metallographic tests. METAL DIE INTERACTION DEFECTS due to metal interaction with the die dimensions in the range µm for soldering and thermal fatigue visual inspections and metallographic tests. GEOMETRICAL DEFECTS excess/lack of material, geometrical non conformity respectively due to an insufficient locking force of the die / excessive melt viscosity and material contraction in solid phase visual inspections. Aluminium oxide 14/22 Crack Soldering

8 MECHANICAL POTENTIAL REFERENCE DIES Alloy Reference die Experimental procedure Optimal conditions & affecting factors Measurement conditions Mechanical potential o Minimized defects o Optimized microstructure STRESS STRAIN CURVES EXISTING STANDARDS ASTM B 108 AFNOR NF A UNI /22 DEVELOPMENT OF 2 PRE NORMATIVE DOCUMENT Alloy Reference die Experimental procedure Optimal conditions & affecting factors Tensile test Mechanical potential 16/22

9 DEVELOPMENT OF 2 PRE NORMATIVE DOCUMENT Process Alloy Temper Casting YS (MPa) UTS (MPa) EL (%) AlSi9Mg0.2 F U HPDC AlSi7Mg0.3 F Hydro AlSi9Cu3 F NADIA U CASTING HYDRO CASTING NADIA CASTING 17/22 DEVELOPMENT OF 2 PRE NORMATIVE DOCUMENT Process Alloy Temper Casting GDC AlSi7Cu3 AlSi7Cu4 AlSi7Mg0.4 F F F ASTM B 108 Steps I Steps II YS (MPa) UTS (MPa) EL (%) ASTM CASTING STEP CASTING I STEP CASTING II 18/22

10 Intensification pressure ENGINEERING RULES Fe platelets Gate velocity Alloy and its properties Type of process and parameters Microstructure Defects Final behaviour 19/22 ENGINEERING RULES microstructural features can be calculated by solidification times predicted using numerical simulation defect content can be evaluated by the use of simulation related quality criteria distribution of mechanical properties can be reasonably achieved by implementing into software tools experimentally derived process, microstructure, defects & properties correlations 20/22

11 BIBLIOGRAPHY E. Gariboldi, F. Bonollo, P. Parona, Handbook of defects in HPDC, (2010), AIM S. Akhtar, G. Timelli, F. Bonollo, L. Arnberg, M. Di Sabatino, A comparative study of defects and mechanical properties in highpressure die cast and gravity die cast aluminium alloys, International Foundry Research/Giessereiforschung 61 (2009) No C. Dørum, H.I. Laukli, O.S. Hopperstad, M. Langseth, Structural behaviour of Al Si die castings: experiments and numerical simulations, European Journal of Mechanics A/Solids 28 (2009) 1 13 G. Timelli, O. Lohne, L. Arnberg, H.I. Laukli, Effect of solution heat treatments on the microstructure and mechanical properties of a die cast AlSi7MgMn alloy, Metallurgical and Materials Transactions A 39A (2008) G. Timelli, S. Ferraro, F. Grosselle, F. Bonollo, F. Voltazza, L. Capra, Mechanical and microstructural characterization of highpressure die cast Al alloys, La Metallurgia Italiana (2011) No C.D. Lee, Effect of T6 heat treatment on the defect susceptibility of fatigue properties to micro porosity variations in a lowpressure die cast A356 alloy, Materials Science & Engineering A 559 (2013) A.M.A. Mohamed, F.H. Samuel, A.M. Samuel, H.W. Doty, S. Valtierra, Influence of tin addition on the microstructure and mechanical properties of Al Si Cu Mg and Al Si Mg casting alloys, Metallurgical and Materials Transactions A 39A (2008) F. Grosselle, G. Timelli, F. Bonollo, Doe applied to microstructural and mechanical properties of Al Si Cu Mg casting alloys for automotive applications, Materials Science and Engineering A 527 (2010) S. Akhtar, D. Dispinar, L. Arnberg, M. Di Sabatino, Effect of hydrogen content, melt cleanliness and solidification conditions on tensile properties of A356 alloy, International Journal of Cast Metals Research 22 (2009) No R. Lumley, N. Deeva, M. Gershenzon, An evaluation of quality parameters for high pressure die castings, International Journal of Metalcasting (2011) S. Otarawanna, H.I. Laukli, C.M. Gourlay, A.K. Dahle, Feeding Mechanisms in High Pressure Die Castings, Met. Mater. Trans. 41A (2010) F. Grosselle, G. Timelli, F. Bonollo, A. Tiziani, E. Della Corte, Correlation between microstructure and mechanical properties of Al Si cast alloys, La Metallurgia Italiana (2009) A.A. Ahamed, H. Kato, Effect of cold flakes on mechanical properties of Aluminum alloy die casts, Proceedings of 10th Asian Foundry Congress, Nagoya Japan (2008) /22 THANKS FOR YOUR KIND ATTENTION Elena Fiorese Department of Engineering and Management University of Padua Str. S. Nicola, Vicenza (Italy) fiorese@gest.unipd.it 22/22