2 A new all in one production process for thin walled Ausferritic Ductile Iron (10 NL 60AH 3H4M)
A new all in one production process for thin walled Ausferritic Ductile Iron (10 NL 60AH 3H4M) A Dutch SME developed a laboratory tested production process of thin walled Ausferritic Ductile Iron (TADI). The process integrates casting with a heat treatment step. Next phase is a demonstration project. Important advantages are high strength material properties, a higher dimensional accurary and less use of material and energy. The Dutch SME is interested in agreements with different partners in the production chain (foundry, OEM, engineer) and research institutes with test facilities.
The TADI production technology combines the new metallurgical procedures for production of thin ductile iron castings with minimum wall thickness of 2 mm with a heattreatment leading to an ausferritic microstructure. The heattreatment is a controlled cooling route directly after casting and solidification to realize heattreated microstructures resulting in advanced high strength cast irons (e.g. ADI-800 ADI-1400) without extra costs for this treatment and with a further environmental improvement of the process concerning dust, energy, chemical emissions. This results in a new moulding line with recently developed moulding materials which are providing less detrimental environmental effects and improved recyclability.
Cast iron is after steel the most important structural material in ground transport, pipes, industrial constructions (Total cast iron volume is 10% of the total steel volume world wide). The production of ductile iron has been steadily increasing over the last years. With the introduction of TADI this increase will be reinforced by the use in light weight, strength critical products.
TADI-material can be used to replace heavy and costly complex welded assemblies, but to make full use of TADI properties a new TADI-directed design/engineering approach is to be considered. Existing value chains need to be adjusted to TADI engineering practices to fully realise the profitable features of this new material. Although modern standard foundry equipments are sufficient for TDI-production specialized high standard series production requires the latest state of technology in engineering and production, which require adaptation of new knowledge & expertise in existing value chains.
In the TADI-approach attention is given to combine automated geometry optimisation, (residual) stress analysis and sophisticated testing with a thermo-graphic-stress-analysis-technique.
The new technology encompass the development of a new production line for ductile iron castings in applications with the following requirements:
- small or medium sized TDI castings
- minimum wallthickness of 2 mm
- maximum freedom of shape
- high fatigue strength (increased Rf/Rm-ratio)
- lower Tough-Brittle-Transition-Temperature (<- 50°C)
- dimensional accuracy sufficient for assembling without further machining (e.g. brackets in building of truck, bus, automotive, agriculture equipment, light rail, furniture, building, . . .