Johny Wahyuadi Soedarsono

Effect of Casting Design to Microstructure and Mechanical Properties of 3 Mm TWDI Plate

The problem occurs in producing thin wall ductile iron (TWDI) is high cooling rate due to its thickness. Cooling rate must be strictly maintained to prevent carbide formation. There are many ways to control cooling rate. Casting design is one of these, especially gating system design. This parameter is often chosen because of its independence. Major changes in equipment and raw material used in the foundry are not needed when a casting design is chosen to deal with cooling rate. This paper discusses the effect of gating system design on microstructure and mechanical properties of 3 mm TWDI plate. A casting design based on gating system design is made to produce 1, 2, 3, 4, and 5 mm TWDI plates. There are three designs coded as T1, T2, and T3. These three designs were also used in making 1 mm TWDI plates of which the result has been published. The plate with thickness of 3 mm will be used for automotive component like the crankshaft made by Martinez. The moulds used were furan sand. Beside the experiment, casting design simulation with Z-Cast was also conducted to see the behaviour of solidification in 3 mm TWDI plate. Simulation result showed every design has its own solidification behaviour for 3 mm TWDI plate, especially for T2. Experiment result showed that all the designs have microstructure consisting of nodule graphite in ferrite matrix, no trace of carbide and skin effect are formed. Skin effect length is various for all designs. Nodularity exceeded 75% and nodule count exceeded 900 nodules/mm2. Brinell hardness number for all design is beyond standard given by JIG G5502. As for UTS and elongation none of the designs exceed the minimal standard. Experiment results confirmed simulation result. Compared to the previous result nodularity and nodule count decrease and curve trends for every result are not the same.

The Use of Mixture of Piper Betle and Green Tea as a Green Corrosion Inhibitor for API X-52 Steel in Aerated 3.5 % NaCl Solution at Various Rotation Rates

Flow induced corrosion due to the presence of turbulent flow often occurs which causes severe internal thinning and promotes premature leakage. In practice, the common method for controlling such internal high corrosion rate is chemical injection using corrosion inhibitor such as amine based which utilizing adsorption or film forming mechanism. Unfortunately, the protection performance of such inhibitor might be less effective due to turbulent flow induced. The aim of this work is to study the use of mixture of piper betle and green tea as an alternative of green corrosion inhibitor (eco-friendly) to reduce the corrosion rate of API X-52 steel in aerated 3.5 % NaCl solution in turbulent flow condition whether high inhibitor efficiency can be achieved. The method of corrosion rate measurements was conducted using electrochemical polarization equipped with CMS100-Gamry Instruments and DC105 software as well as Rotating Cylinder Electrode (RCE) simulation. The mechanism of inhibition was also investigated using Electrochemical Impedance Spectroscopy (EIS) method with EIS300 software. The results showed that the addition of mixture of 1000 ppm piper betle and 4000 ppm green tea extracts with Reynold number ranging from 0 up to 30000 reduced the corrosion rates significantly with its approximately 90 % inhibitor efficiencies achieved. In addition, EIS spectra showed that in the absence of corrosion inhibitor, the Warburg impedance (diffusion controlled) was significantly attributed to the overall impedance but in the presence of corrosion inhibitor, capacitive impedance (charge transfer controlled) was mainly attributed to the overall impedance.

The Effects of Plates Position in Vertical Casting Producing Thin Wall Ductile Iron

In the general rule of casting design the thickest part of the cast should be placed near to the ingate. This arrangement was meant to guarantee the completion of filling process. An unusual vertical casting design to produce plates with different thicknesses was established based on the idea that the heat from molten metal will always warm up its entire runner. In this design the thinnest plate is placed near to the ingate. The design was made for producing thin wall ductile iron. This research was conducted to see the effects of reverse thickness arrangement in casting design to the microstructure and mechanical properties of the plates. Plates produced by this design were compared to plates produced by the same design with general casting arrangement. Thicknesses of the plates produced in this casting were 1, 2, 3, 4, and 5 mm. The moulds used were made from furan sand. Beside experiment, casting design simulation with Z-Cast was also conducted to ensure the completion of filling process and to see the manner of solidification. Casting simulation showed that arrangement of plates gave different filling and solidification manners. Although there were some differences, the filling was successful for both arrangements of plates. Skin effect was found in both designs. Nodule counts and nodularity were higher in the new design while average nodule diameters were lower. The result gained in tensile and hardness test did not follow the correlations in the characteristic of graphite. Mechanical properties showed that position of plate, ignoring the thickness, influence tensile strength and hardness.

Cooling Rate Analysis of Thin Wall Ductile Iron Using Microstructure Examination and Computer Simulation

Cooling rate plays an important role in thin wall ductile iron solidification, due to their thickness. Casting simulation is use as a tool to estimate the cooling rate. In the other hand, every microstructure has its own cooling rate. This paper explores the similarity of solidification mechanism between simulation and graphite characteristics. Three types of casting design simulated and produced. Solidification mechanism is analyzed based on cooling rate sequence and trend line matching. Temperature gradient and thermocouple function represent simulation while graphite characteristic represent experiment. The result shows that similarity in solidification mechanism is not found between simulation with experiment due to lack of parameters in both sides.

The Effect of Vertical Step Block Casting to Microstructure and Mechanical Properties in Producing Thin Wall Ductile Iron

Thin wall ductile iron (TWDI) is introduced to fulfill the needs of lighter material in automotive parts that will reduce fuel consumption. Problem occurs during the production of TWDI due to the casting thickness. TWDI casting thickness classified to below 5 mm. Many designs have been made to answer the problem in producing thin wall ductile iron. Soedarsono et al established vertical step block casting design. This design based on Y-block principle that allows direct pouring of liquid metal to the mold without passing any gating system. This design will increase casting yield. The parameter of this research is pouring basin placement to study the effect of plate arrangement to filling and solidification. This research is conducted to see the effect of pouring basin placement to microstructure and mechanical properties of TWDI. The Design is made to produce 5 plates with different thickness that is 1, 2, 3, 4, and 5 mm. All of the plates arranged parallel in line. Pouring basin located in 2 ways. The first type located pouring basin above the plate of 5 mm thickness while the second one located it above the plate with 1 mm thickness. The first type coded as T4 while the second coded as T5. The moulds made from furan sand. The result shows although cold shut occurred in both pouring basin placements due to pouring discontinuity but shrinkage only formed in T5 on its plate with 1 mm thickness. Microstructure of all the plates presented nodule graphite in pearlite matrix. Carbide and skin effects also detected. Average nodularity is above 80% while the nodule count is between 614 to 1269 nodule/mm2. Most of the Brinell hardness number exceeded maximum limit given by JIS G5502 but the UTS is below the minimum limit except for 3 mm plate thickness of T5. All elongation values below the minimum standard. The results confirm that pouring basin location is important in casting design following Y-Block principle.

Effect of Reduction Process Parameter in Direct Reduction Process of Laterite to Produce Substitute Pig Iron for Thin Wall Ductile Iron Material

Many parameters are involved in reduction process but carbon availability, process temperature and process time hold the role. This research conducted to find the relation effects of three main factors mention previously. This research used lateritic rocks from Sebuku Island as the iron source and coal as carbon source. Particle size with the highest Fe content is used for reduction process. Variations in reduction process made in mass ratio, process temperature, and process time. The mass ratios are 1:4 and 1:5. The process temperatures are 900OC and 1000OC. Process times are 10, 20, and 30 minutes. Characterization process used XRD and XRF. The results show that carbon availability is important and combinations of higher carbon supplies and process temperature are able to prevent further oxidation.

Reduction of Composite Pellet Containing Indonesia Lateritic Iron Ore as Raw Material for Producing TWDI

Blast furnace process is still an important process for producing pig iron. The process needs high grade iron ore and coke. The two materials can not be found easily. In addition blast furnace process needs cooking and sintering plant that produces polluted gases. Utilization of composite pellet for pig iron production can simplify process. The pellet is made of iron ore and coal. In addition the pellet can be made from other iron source and coal. This paper discusses the evolution of phase during reduction of composite pellet containing lateritic iron ore. Fresh iron ore and coal were ground to 140 mesh separately. They were mixed and pelletized. The quantity of coal added was varied from 0 %, 20 % and 29 % of pellet weight. Pellets were heated with 10 °C/minute to 1100 °C, 1200 °C, 1300 °C and 1350 °C in a tube furnace and temperature was held during 10 minutes. Heated pellets were analyzed with XRD equipment. XRD of reduced pellets showed that iron phase change with coal and temperature. Lack of coal during heating results the re-oxidation of iron phases. This process is due to replacement of reductive atmosphere by oxidative atmosphere.

Corrosion Inhibition of Low Carbon Steel by Pluchea Indica Less. in 3.5% NaCL Solution

Inhibition of low carbon steel (LCS) corrosion in 3.5% NaCl of Pluchea indica Less. leaves extract (PILLE) has been studied using various investigation techniques such as weight loss and polarization methods. The percentage of inhibition increased as the concentration of the inhibitor increased. The results of corrosion test reveal that the extract behaves as a mixed type corrosion inhibitor. Optimum inhibition is reached from 3 mL gambir extract for immersion time of 216 hours. Fourier transform infrared (FTIR) spectroscopy result of adsorbed film on LCS surface containing PILLE shows that in changes in the functional group frequencies of the organic component of the extract.

Potential Indonesia Ores as Raw Material for Producing Iron Nugget

Indonesia due its archipelago has so many kinds of rocks which contain ores. With the finding in technology iron source is not iron ore alone like it use to be in the past. This research is conducted to see availability of mineral rocks in Indonesia as iron source. Four different kinds of mineral rocks are used. They are: limonite, saprolite, malachite, and chalcopyrite. Separation of limonite is done by magnetic separation process while saprolite, malachite, and chalcopyrite are done by washing separation methods. Analysis on Fe content is done at origin and roasting condition for all rocks. The results show that other mineral rocks can become iron source, separation will enhance Fe content, and lateritic nickel rocks especially limonite can be new other iron source.

Effect of Casting Design to Microstructure and Mechanical Properties of 1 mm TWDI Plate

In producing thin wall ductile iron (TWDI) cooling rate must be strictly maintaned to prevent carbide formation. There are many ways to control cooling rate and one of these is through casting design, especially gating system design. This paper discusses the possibility to produce 1 mm TWDI plate and also to note the effect of gating system design to microstructure and mechanical properties. Casting design based on gating system design are made to produce 1 mm TWDI plate. The 1 mm TWDI plates will be used for fin. There are three design and coded as T1, T2, and T3. The moulds used were made from furan sand. Beside the experiment, casting design simulation with Z-Cast was also conducted to ensure the completion of producing 1 mm TWDI plate. Simulation result showed that all designs could produce 1 mm TWDI plate. Result from experiment showed that all the designs have microstructure consisting of nodule graphite in ferrite matrix and carbide. Apart from mentioned microstructure there is also skin effect. The difference between all designs lies in carbide content and skin effect width. All the nodularity exceeded 80% and nodule count exceeded 1000 nodule/mm2. Brinell hardness number for all design exceeded minimal standard given by JIG G5502. As for UTS only T2 design can exceed the minimal standard. There is a contradictive result between experiment and simulation in cooling rate.