Optimized DISA system parameters of a thin-wall malleable iron pipe casting by numerical simulation

The filling and solidification of a malleable iron pipe casting manufactured by DISA casting mold line with different design parameters were calculated by using software MAGMASOFT. Then the shrinkage porosity was predicted by thermal criterion. Based on the simulation results, the influences of the runner ratio and feeder position on the porosity were discussed. The results show that synchronization of injection can be significantly influenced by the size of downsprue section, and an de-sign structure of DISA gating system was used to solve the problem of flow imbalance in the filling procegs. At the same time, the riser was designed on the hotspot for feeding shrinkage. At last, the optimizated gating system and feeding system were ac-complished to eliminate shrinkage porosity.

Oil quenched malleable iron,the strength of an old material in a “green cast” development and a new future

Malleable iron lost the interest and the development stopped in the turbulent seventies of tremendous developments of new technologies. The personal computer, emission spectrometer, thermal analysis, cold-box core system and automatic vertical moulding were introduced into the foundry industry. Experience shows that these new technologies do not always match up with malleable iron. Solidifciation and mould filling simulation programs are not always capable to handle a low carbon equivalent iron like malleable iron. Recent developments show however by using these new technologies and combined with practical experience, it is possible to increase the casting yield of malleable iron to the same level as ductile iron. The mechanical properties, especially the yield strength of malleable iron according to the standard are equivalent to those of ductile iron, however the yield strength of oil quenched malleable iron is signifciantly higher than that of ductile iron. An extensive investigation is made between ductile iron, air quenched and oil quenched malleable irons based on the properties of more than 350 test bars produced under the same conditions. The results are compared with the existing international standards and discussed. Other properties like fatigue strength and response to surface treatments as induction hardening are also discussed. The costs of malleable iron are reviewed and compared with other ferro alloys. These recent developments in increasing the casting yield, the understanding of the strength, makes malleable iron competitive with ductile iron and cheaper than the first grade of ausferritic ductile iron, or steel qualities. It is possible to design lighter and save weight which is essential in the automotive industry. An example of "green cast" development for typical applications, used in automotive transmissions and engines are shown.

Role of RE and Mg on Graphitization of Spheroidal Graphite Malleable Cast Iron

Spheroidal graphite malleable cast iron is a new structural material developed in the recent years. This paper studies the influence of the residual content of rare earth and magnesium on the nodule counts, the time of first stage graphitization and the rate of ferritization of it. Moreover, the role of sulfides of rare earth and magnesium in the process of graphitization has been analyzed. The results show that the residual content of rare earth and magnesium has a notable influence on the graphitic nodule counts and the time of the first stage graphitization of spheroidal graphite, but has unremarkable influence on the time of the second stage graphitization. There are a large number of spherical sulfides of rare earth and magnesium in as-cast structure, which will act as the nucleus of graphite in the process of first stage graphitization.

High-Speed Machining of Malleable Cast Iron by Various Cutting Tools Coated by Physical Vapor Deposition

The coating material of a tool directly affects the efficiency and cost of machining malleable cast iron.However,the machining adaptability of various coating materials to malleable cast iron has been insufficiently researched.In this paper,turning tests were conducted on cemented carbide tools with different coatings(a thick TiN/TiAlN coating,a thin TiN/TiAlN coating,and a nanocomposite(nc)TiAlSiN coating).All coatings were applied by physical vapor deposition.In a comparative study of chip morphology,cutting force,cutting temperature,specific cutting energy,tool wear,and surface roughness,this study analyzed the cutting characteristics of the tools coated with various materials,and established the relationship between the cutting parameters and machining objectives.The results showed that in malleable cast iron machining,the coating material significantly affects the cutting performance of the tool.Among the three tools,the nc-TiAlSiN-coated carbide tool achieved the minimum cutting force,the lowest cutting temperature,least tool wear,longest tool life,and best surface quality.Moreover,in comparisons between cemented-carbide and compacted-graphite cast iron machined under the same conditions,the wear mechanism of the coated tools was found to depend on the cast iron being machined.Therefore,the performance requirements of a tool depend on multiple factors,and selecting an appropriately coated tool for a particular cast iron material is essential.

EFFECT OF STRUCTURE ON GRAPHITIZATION OF WHITE MALLEABLE CAST IRON

The structure of white iron treated with Si-Bi-AI complex inoculant has been observed by SEM and TEM. The results show that, in comparison with the samples treated with ordinary inoculants, disorder, overlapping and inflexion of the pearlitic lamella appear, besides, the dis- location density increases apparently. The graphitization can be quickly realized at the tem- perature lower than that of austenitic transition (720℃).