The performance of laser surface processed aluminum alloys for commercial applications

Abstract

The extensive variety of materials now available for both civilian and military applications provides the engineer with the freedom to select those with adequate if not superlative properties. But just as the variety of materials has expanded, so has the multitude of applications, once again pushing the limits of the available materials and challenging the materials scientist One particular set of materials, the aluminum alloys, has been receiving significant interest because of its ability to reduce the weight of a component, thereby increasing efficiency or otherwise improving economics. Unfortunately along with weight loss, there is an associated loss in wear resistance which makes the use of these alloys questionable for many applications. One solution to this problem is the application of a surface to the aluminum that has the desired properties. An example of a desirable base material with undesirable surface properties is the cast aluminum alloys used in the automotive industry. Their poor wear properties have given rise to a number of fixes for making the automotive cylinder bore more durable. Iron liners are typically inserted, or more recently, cast into the aluminum block significantly increasing the wear resistance by the presence of the graphite in the iron. Unfortunately, the additional weight of the liners can be considerable, 10 - 20% of total block weight, and there is a significant reduction in possible engine displacement for a given engine envelope. In searching for replacements for the iron liners, technologists have developed an interesting variety of surface modification techniques, one of which will be examined in this paper (Laser Induced Surface Improvement). Regardless of the surfacing technique, a consideration which must always be addressed when considering surface alloying for wear resistance is the level of wear resistance needed by the surface. For the case of cylinder bores which must be honed and even possibly machined after processing, the wear properties should be improved only to the extent necessary for use in the application. On the other hand, there are a large number of applications for aluminum that require the highest possible wear resistance, demanding a different additive combination approach from that of the medium wear requirements of automotive cylinders. Therefore, this study was divided into two Applications. Application I which examined a variety of material combinations and processing parameters, and consisted of identifying a material additive combination for 319 aluminum that would produce wear properties similar to or slightly better than cast iron, a very popular cylinder alloy. Since the second application required the highest possible wear resistance, Application II consisted of determining the additives for 5083 aluminum that would come closest to satisfying that requirement.The extensive variety of materials now available for both civilian and military applications provides the engineer with the freedom to select those with adequate if not superlative properties. But just as the variety of materials has expanded, so has the multitude of applications, once again pushing the limits of the available materials and challenging the materials scientist One particular set of materials, the aluminum alloys, has been receiving significant interest because of its ability to reduce the weight of a component, thereby increasing efficiency or otherwise improving economics. Unfortunately along with weight loss, there is an associated loss in wear resistance which makes the use of these alloys questionable for many applications. One solution to this problem is the application of a surface to the aluminum that has the desired properties. An example of a desirable base material with undesirable surface properties is the cast aluminum alloys used in the automotive industry. Their poor wear pro...