OPTIMIZED DURABILITY PREDICTION
OF CAST IRON BASED ON LOCAL MICROSTRUCTURE
A casting design where the application load and weight are optimized is only achievable if the designer can fully unlock the potential of the material. A research project studied how to integrate process and application simulation for the development of more realistic design rules for cast parts.
C
CORINNA THOMSER, MATHIAS BODENBURG, AND JOERG C. STURM, MAGMA GIESSEREITECHNOLOGIE GMBH (AACHEN, GERMANY)
ompared to the conventional design of castings, a substantial qualitative and quantitative improvement in assessing t he real performance of cast iron materi- als can be realized. T e casting process has an essential impact on
the creation of the local microstructure of a casting. T ese local variations in microstructure lead to lo- cally varying mechanical properties. T e properties of
cast iron castings depend on their geometry and are mainly driven by the graphite morphology, microstructure, and discontinuities. T erefore, the chosen metallurgy and process control are essential parameters for the performance. T e conventional casting design process does not consider the impact of micro-
structure variations on the fatigue/lifetime performance of castings. T e designer lays-out castings based on established standards. T ese standards assume ho- mogenous properties throughout the entire casting. As a result, only one material dataset is considered in fatigue/lifetime prediction analysis tools. Local residual stresses and microstructure variations are rarely recognized in
lifetime prediction simulations. T is leads to underestimating failure risks and fail- ing to utilize the full performance potential of the material. Designers are uncer- tain how close the expected mechanical properties match the ones found in the real castings. A conservative design approach requires them to apply safety factors, which lead to unnecessarily high weight and resulting costs.
Metalcasting engineers suff er from
undesired consequences created by this approach as well: safety factors result in thicker walls, which increase solidifi cation times and usually lead to decreased mechanical properties. T ey are also tougher to feed and cause increasing residual stresses within the casting during its cooling process. Coupling casting process simula-
tion with fatigue/lifetime prediction analysis is necessary to unlock the full potential of cast materials. Cast- ing process simulation tools need to provide answers to questions engi- neers and casting designers have. It must qualitatively and quantitatively describe material and mechanical properties (Fig. 1). Integrating local properties allows the designer to customize the casting design for the specifi c requirements of
Mar/Apr 2017 | METAL CASTING DESIGN & PURCHASING | 23
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60