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The lost foam casting process (LFCP) is a near-net shape casting process. This process is the most energy efficient casting process available. “Foundry Management and Technology” magazine analyzed the lost foam process and reported a 27% energy savings, a 46% improvement in labor productivity and 7% less material usage compared to other casting processes. The LFCP produces high value parts by combining multiple components into single castings, improving energy efficiency by achieving better metal yields, reducing materials consumption by eliminating cores, providing minimal post casting processing and improving as-cast dimensional accuracy. All of these process features reduce the total energy consumed during manufacturing.

Elevated temperature bolt load compressive stress retention testing of four high temperature magnesium alloys (AJ50X, AJ52X, AS21X and AE42), two structural magnesium alloys (AM50A and AM60B), one aluminum alloy (383) and one gray iron alloy were performed at the INTERMET Technical Center over a period of about one year. Artificial aging of some of these alloys during testing was observed. The effect of a heat treatment designed to thermally stabilize the microstructure was evaluated and determined to significantly improve magnesium performance and degrade aluminum performance. This paper documents the test procedure and the test results.

The automobile and light truck industries are increasing considering the use of magnesium castings in structural and elevated-temperature applications. Unfortunately, the bolt load compressive stress retention behavior of magnesium alloys is unacceptable for most elevated temperature applications. In this investigation, the effects of bolt strength and the mis-match in the coefficient of thermal expansion (CTE) of magnesium alloy AZ91D and the bolt material has been determined for a wide range of materials (martensitic steel, austenitic stainless steel, ductile iron and aluminum alloys). Also, the effect of heat treating the magnesium alloy, the effect of re-tightening the bolts after the first thermal cycle and the maximum load carry capacity of numerous bolt materials were determined. Corrosion was not considered.

SAE 1046 steel axle I-beam forgings produced by the direct quench method and the conventional reheat and quench method were examined. Impact and tensile specimens obtained from sections of two direct quench and one conventional reheat and quench axle I-beams were tested. These data were correlated with hardness and microstructure to determine the relationship between microstructure and properties. The microstructure of direct quenched beams is coarse grained with a martensite case and bainite core. In contrast, the microstructure of conventionally heat treated beams is fine grained with a martensite and/or bainite case and pearlite core. Tensile and impact properties indicate that direct quenching is an acceptable alternative to the conventional reheat and quench process. Fatigue testing of direct quenched beams is currently being performed.

A variety of new magnesium casting alloys specifically designed for high temperature applications are currently available. However, there is little published data from component tests or from test specimens sectioned from component castings. In this study, the mechanical properties (tensile, bracket thread integrity, bracket distortion and fastener/attachment point acceptability) of front engine covers made from three magnesium alloys (AZ91D, AJ62x and MRI-153M) and from aluminum alloy 380 are presented.

The automobile and light truck industries are increasingly using more magnesium castings in structural and high-temperature applications. Unfortunately, the castability and mechanical behavior of the commonly used alloys have not been compared under similar conditions. Further, new alloys intended for high-temperature applications (Noranda AJ50X, Noranda AJ52X, Hydro AS21X, Dead Sea Magnesium MRI-153) are being promoted, but their casting and mechanical behavior are not well known. Therefore, five high temperature magnesium alloys (AJ50X, AJ52X, AS21X, MRI-153 and AE42), two magnesium alloys more commonly used for structural applications (AM50A and AM60B) and one aluminum alloy (383) were melted and cast at the INTERMET Monroe City Plant (a production high-pressure die casting facility). The castings were subsequently evaluated at the INTERMET Technical Center and outside testing laboratories.

The automotive industry continues to look for opportunities to reduce weight and cost while simultaneously increasing performance and durability. Since the introduction of aluminum cylinder blocks and heads, very few “innovations” have been made in powertrain design and materials. Cast crankshafts have the potential to produce significant weight savings (3-18 kg) with little or no cost penalty. With the advent of new, high strength, cast ductile iron materials, such as MADI™ (machinable austempered ductile iron), which has the highly desirable combination of good strength, good toughness, good machinability and low cost, lightweight crankshafts are posed to become a high volume production reality. An extreme demonstration of a lightweight crankshaft is the current use of a cast MADI crankshaft in the 1100 HP Darrell Cox sub-compact drag race car.

The use of aluminum to produce lightweight automotive castings has gained wide acceptance despite significant cost penalties. Lightweight iron and steel casting designs have been largely ignored despite their obvious cost and property advantages. This paper reviews and discusses the following: 1) various processes for producing lightweight iron and steel castings, 2) examples of lightweight components in high-volume production, 3) examples of conversions from aluminum to iron, 4) material properties of interest to designers, 5) examples of concept components and 6) efforts to improve the design and manufacturing processes for lightweight iron and steel castings. In summary, the potential for low-cost, lightweight iron and steel castings to aid the automotive industry in achieving both cost and weight objectives has been demonstrated and continues to expand. In general, however, automotive designers and engineers have not yet fully taken advantage of these technologies.

Squeeze casting and semi-solid metal forming produce aluminum castings with exceptional properties. This paper compares the mechanical properties and microstructures of a production component processed by a variety of casting processes and heat treatments. Note, in all cases, the current insert tool used for squeeze casting was adapted to be utilized in the various semi-solid metal forming processes. The results showed that semi-solid metal forming produced consistently better mechanical properties compared to squeeze casting. Defects, primarily oxide films, were determined to be responsible for the lower and less consistent properties of the squeeze cast material.