Rianti Dewi Sulamet-Ariobimo

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.

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.

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.

The Effect of Reduction Parameter in Processing Lump Ore with Green Sugarcane Bagasse Reductor in Muffle Furnace

Sugarcane bagasse has demonstrated its ability to act as a reductor in iron-reduction process. As a reductor, bagasse has specialties as double-acting reductor equiped with volatile matter. This is the first study of the use of bagasse as reductor in iron-reduction process. The parameter concluded from this study was used for the second study which report has been submitted for publication. The aim of this study is to discuss the effect of reduction process parameter to the use of bagasse as reductor. This study was divided into 2 step. The first step is determining the optimum reduction process temperature and weight ratio. The reduction temperature varied as 700, 800, 900 and 1000 °C and the weight ratio are 1:2 and 1:4. The process duration is 30 minutes. The second stape is determining the process duration. The process duration will be varied as 30, 45 and 60 minutes. The condition of bagasse is air dried basis. The result shows that the reduction process produced wustite (FeO).

The Effects of Reduction Parameter to Composite Pelet of Iron Ore and Coal Using Single Conveyor Belt Hearth Furnace

Iron ores should be separated from oxygen and impurities which are coming along during the mining process. The separation process is known as reduction. There are two types of reduction process, and the most common is direct reduction process (DRP). There are several parameters in DRP which will determine the quantities of the product known as direct reduction iron (DRI). This worked discussed the effect of reduction temperature and pellet heap to the quantities of DRI using single conveyer belt Hearth furnace. The worked was done in laboratory scale using composite pellets with 14 mm in diameter. The ratio of iron ore to coal in the composite pellet is 1 to 1. The reduction process temperatures are 500oC, 700oC and 900oC. The reduction time is 25 minutes. While the pellets heap are also varied to 1, 3, 5, 7, 8 and 9 layers. The results show that DRI was formed in 700OC and the quantities of DRI are in line with the reduction temperatures and layers of composite pellets heap.

Effect of Carbon Content in Direct Reduction Process of Limonite Iron Oxide to Produce Pig Iron Substitute for Thin Wall Ductile Iron Process

Quality molten metal needed to produce thin wall ductile iron (TWDI). Pig iron, as the major base material to produce quality molten metal, due to its high price, has been change with scraps. The use of scrap as major base material associates with more cleaning and chemical composition adjustment. The ITmk3 technology in iron making has successfully produced iron nugget. Iron nugget can be use to substitute pig iron due to its quality that is comparable to pig iron but lower in price. This research conducted to see the effects of carbon content in producing iron nugget. Limonite iron ores used in this research are part of laterite rocks taken from Sebuku Island in South Kalimantan, Indonesia. Variation made to weight of carbon mixed with laterite. Heating temperatures of direct reduction process are 700°C, 900°C, and 1000°C. The process times are 10, 20, and 30 minutes. XRF used in analysing Fe content in laterite and XRD is used in analysing result of direct reduction process. The result shows that increasing carbon content to certain condition will increase the rate of gasification process during direct reduction. The increase of gasification rate will result to higher Fe formation.

The Influence of Coal and Reduction Process Parameters in Producing Iron Nugget

Limitation of iron ore reserve having high quality ore and of energy has enhanced development in iron and steel producing technology and method. The ITmk3 process is one of iron making technology that can cope with the problems. It uses composite pellet as feeding material. In this process the ratio between iron and carbon are very important. Carbon holds an important role in the reduction process of iron. The transformation from iron oxides to iron metal will complete if composite pellet contains enough carbon. This paper discusses the influence of carbon ratio in iron reduction process. Nickel saprolite and coal are used as iron and carbon source. They are grinded, crushed, sieved, mixed and formed in cylinders. The weight ratios of ores to coal are 1:1 and 2:1. The reduction held in a furnace at 1100OC for 60 minutes and 1250OC for 120 minutes. The results show that the reduction could not complete. Weak peak of FeNi is due to reduction process do not immediately follow the dehydroxylation process.