Materials Science Forum Vol. 1066

Abstract: Resin Coated Sand (RCS) is an important raw material for the Shell mould process. This research aimed to study the effect of silica content on the surface quality of cast iron in the shell mould process. The four kinds of sand are Australian sand, Rayong sand, Reclaimed sand and River sand. All sand was mixed with phenolic resin for making Resin Coated Sand. The chemical composition of sand was tested by X-Ray Fluorescence. The result found that the SiO₂ content of each sand was different. The SiO₂ content of Australian sand 99.8%, Rayong sand 98.6%, Reclaimed sand 90.3% and River sand 89.2%. The morphology from the microscope was found that sand grains exhibited different shapes that affect mechanical properties such as bending strength and thermal expansion of Resin Coated Sand. The qualification of Resin Coated Sand is bending strength and thermal expansion from Australian sand is the highest. On the other hand, River sand is the lowest bending strength and thermal expansion. The casting result showed that the burn on and veining defects were found on the casting surface. The veining occurred with Australian sand. While, the burn on occurred with Rayong sand, Reclaimed sand and River sand.

Abstract: The temperature of a strip cast using a vertical type high-speed twin-roll caster was measured by inserting a k-type thermocouple into the strip. The effects of the roll speed and roll load on the cooling rate and temperature at the roll gap were investigated using two aluminum alloys: A383 and Al–4.8%Mg. The thickness of the thermocouple was 0.1 mm, and the sampling time was 0.01 s. The cooling rate increased and the temperature at the roll bite decreased with decreasing roll speed and increasing roll load. The positions of the liquidus and solidus lines were measured, and the reduction of the thickness of the strip was inferred from the roll gap at the solidus line.

Abstract: solidification, process shortening and energy saving. A twin-wheel caster equipped with two additional horizontal wheels was proposed to cast thin aluminum alloy wire at higher speed. In the proposed twin-wheel caster, a groove was machined on the lower wheel. Two small horizontal wheels were positioned between the molten-metal-pouring launder and the upper wheel to assist the solidification of poured molten metal and to prevent burr formation. The alignment of the horizontal wheel sensitively affected the occurrence of wire defects. An Al-1.2%Fe wire with a cross section of 6.2 mm² was cast at 15 m/min. Thinner wires without burring could be cast at a speed higher than that of the twin-wheel caster without the horizontal wheels. The surface condition of the as-cast wire cast by the twin-wheel caster equipped with horizontal wheels was worse than that of the casting using the twin-wheel caster without horizontal wheels.

Abstract: In order to realize the CNC incremental forming of the straight wall parts, a CNC incremental forming method with the sheet metal posture adjustment in multiple directions based on the model partition and the non-steep surface was proposed in this paper. With the help of the non-steep surface, the sheet metal posture is adjusted to reduce the forming angle of the straight wall; to ensure the straight wall to be formed without breaking. The results of numerical simulation shows that the method proposed in this paper can form the straight wall parts that cannot be formed by the traditional multi-pass incremental forming, and the straight wall parts of the formed parts have better contour accuracy, uniform thickness distribution and applicability.

Abstract: In the multi-stage incremental forming of straight-wall parts based on the extrusion from the forward and reverse side of the sheet, different forming area zoning will have different effects on the part thickness. The larger the area of the sheet metal participating in forming is, the better the thickness distribution is. However, the forming area zoning can be adjusted by using the inclination angle α and the height H of the auxiliary zoning surface. Research results show that the forming area of the sheet metal participating the forming will increase and the thickness of the formed part will also increase with the inclination angle α decreases and with the height H increases.

Abstract: In orbital welding technology, it is difficult and time-consuming to make a standard weld by manual welding. This requires a skilled weld. Therefore, a more optimal welding method than automatic rotary welding has been created to replace the conventional manual welding method. This significantly improves weld quality and reduces welding time. In this explanation, we have experimented with an automatic orbital welding device that integrates a filler wire-feeder device into the welding process. We refer to the American National Standard AWS D18.1/D18.1M: 2009 documents to review the weld results. We then analyze the advantages and disadvantages of the weld and propose solutions.

Abstract: Stainless steel may be susceptible to localized corrosion. Despite this fact, still too many infrastructures are planned with an inadeguate metal chemical composition or placed in wrong environments. In most cases, a clear underestimation of these factors affects the stainless steel durability. These unexpected issues cause a significant technical and economical impact. In this work, several case studies of Inox exposed to unfavorable environmental conditions are presented. A wide range of structures, such as house handles, a swimming pool, a parapet, an industry plant and a waste water collection tank are investigated with respect to the corrosion behavior. Temperature and humidity cyclic variation, promote the enrichments of aggressive agents and lead to degradation. A too low Molybdenum content of the steels is inadequate for some type of structures and service conditions. The weldability changes depending on the steel type and along the thermally affected zones, intergranular corrosion may appear. In addition, a galvanic contact of the stainless steel with existing low alloyed steels components promotes the deterioration of the latter.

Abstract: In this paper, the simulated welding structure of austenitic stainless steel is prepared by external heating, and the corrosion resistance of austenitic stainless steel in different areas of heat affected zone (HAZ) is evaluated by means of metallographic structure analysis, electrochemical impedance spectroscopy (EIS) test and equivalent circuit numerical fitting analysis. The result shows that the simulated welding structure of austenitic stainless steel had a growth trend with the increase of heating temperature, but the growth trend is not very obvious. The short thermal process has insufficient driving force for the growth of single-phase austenitic structure. The resulting of product resistance and charge transfer resistance of simulated welding microstructure of austenitic stainless steel is not completely consistent. The simulated welding microstructure of stainless steel shows the tendency of corrosion resistance degradation with the heating temperature increasing, and it has slightly lower when the maximum heating temperature locating at 1000-1100 °C.

Abstract: In this paper, the simulated welding structure in different area of heat affected zone (HAZ) of S30408 austenitic stainless steel are prepared, and the corrosion resistance properties are evaluated by electrochemistry method and micro-morphology analysis. The result shows that the corrosion resistance of different areas of the HAZ presents different performance, and the corrosion resistance of the area with the highest heating temperature of 1000-1100 °C is slightly lower than that of other areas.The micro-morphology shows that the pitting of the simulated structure in the HAZ have a certain orientation. The rapid cooling process at high temperature is conducive to the uniform distribution of alloying elements, and it can increase the pitting corrosion resistance of the raw material.