Laser metal deposition of steel components using machining waste as build material
Gas atomised metal powders are generally used in laser cladding. However, costly new powders prompt the use of machining swarf as an alternative build material. This paper reports on this investigation and establishes its feasibility.
Laser Metal Deposition of Metals and Alloys
Laser metal deposition process has evolved over the past two decades and it has provided the needed solution into a number of engineering problems. The capability of this additive manufacturing technology to produce end used parts directly from metals and alloys is one of the attractive features of this manufacturing process. Laser metal deposition process can be used to create parts without the need for expensive and time wasting tooling. This technology helped to build near net shape components simply by adding materials layer after layer using the three dimensional (3D) model data of the part to be built. Laser metal deposition process is a true green manufacturing process that is capable of reducing material and energy wastages, help to reduce component lead time, and can also help to reduce carbon footprint through product remanufacturing capability. Any complex part that is difficult or prohibitive to be fabricated using the conventional manufacturing processes can readily be made using the laser metal deposition process. In this chapter, the use of laser metal deposition process for the processing of metallic materials and alloys are discussed. The current research activities and the future research direction are also presented.
Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
Abstract The Song-Nen Plain in northeastern China holds one of the three largest expanses of soda saline-alkali soil in the world. Due to its disadvantageous geotechnical properties, the saline soil in this area is unable to meet the needs of construction projects. This study evaluates the stabilizing effect of adding lime to such soils. Specifically, it investigates how the physicochemical and mechanical properties and microstructure of soda saline-alkali soil are altered by lime and how these changes are affected by both freeze-thaw cycling and the duration of curing. The results reveal that adding lime to saline soil transforms clay particles into sand and silt particles and causes the pore size distribution (PSD) to become bimodal, with small-pore and macropore populations. An increase in lime content leads to an increase in the unconfined compressive strength (UCS) but a gradual decrease in both the cation exchange capacity (CEC) and plastic index. Freeze-thaw cycles break up coarse particles and aggregate finer particles, increasing the diameter of macropores and decreasing the USC; however, the effect on specimens with >9% lime is negligible. It is further shown that the geotechnical properties of the soil change immediately after the addition of lime, indicating that the cation exchange reaction takes place very quickly. Furthermore, the pozzolanic reaction leads to an increase in the percentage of sand-sized particles and a decrease in porosity after 28 days of curing. Overall, these results indicate that it is feasible to use lime to improve the engineering properties of soda saline-alkali soil in this area.