Rasheedat M. Mahamood

Characterizing the Effect of Laser Power Density on Microstructure, Microhardness, and Surface Finish of Laser Deposited Titanium Alloy

This paper reports the effect of laser power density on the evolving properties of laser metal deposited titanium alloy. A total of sixteen experiments were performed, and the microstructure, microhardness and surface roughness of the samples were studied using the optical microscope (OP), microhardness indenter and stylus surface analyzer, respectively. The microstructure changed from finer martensitic alpha grain to coarser Widmastatten alpha grain structure as the laser power density was increased. The results show that the higher the laser power density employed, the smoother the obtained surface. The microhardness initially increased as the laser power density was increased and then decreased as the power density was further increased. The result obtained in this study is important for the selection of proper laser power density for the desired microstructure, microhardness and surface finish of part made from Ti6Al4V.

Types of Functionally Graded Materials and Their Areas of Application

Functionally graded materials (FGMs) are advanced composite materials that are used to solve a number of engineering problems, as well as in the biomedical implant applications for the replacement of human tissues. These materials are used to eliminate the stress singularities that occur, as a result of the property mismatch in the constituent materials in a composite. There are different types of FGMs that are used today, depending on the type of application, for which the material is intended. In this chapter, the different types of FGMs are presented. The areas of application of this novel material are also explained.

Modelling of Process Parameters Influence on Degree of Porosity in Laser Metal Deposition Process

Additive manufacturing process is an advanced manufacturing process that fabricates component directly from the three dimensional (3D) image of the part being produced by adding materials layer by layer until the part is completed. Laser Metal Deposition (LMD) process is an important additive manufacturing technique that is capable of producing complex parts in a single manufacturing run. A difficult to manufacture material such as Titanium and its alloys can readily be manufactured using the LMD process. Titanium and its alloys possess excellent corrosion properties that made them to find applications in many industries including biomedical. The biocompatibility of Ti6Al4V made then to be used as implants. Porous implants are desirable in some applications so as to reduce the weight as well as to aid the healing and proper integration of the implant with the body tissue. In this chapter, the effect of laser power and scanning speed on the degree of porosity was investigated and empirically modelled in laser metal deposition of Ti6Al4V. The model was developed using full factorial design of experiment and the results were analyzed using Design Expert software. The model was validated and was found to be in good agreement with the experimental data.

Laser Metal Deposition Process for Product Remanufacturing

Remanufacturing is a process of bringing a damaged part back to its perfect working condition. The cost of remanufacturing equipment or parts is cheaper than the cost of buying a new one. The conventional manufacturing method involves processes which are energy inefficient that causes lots of emissions, thereby contributing immensely to the global warming problems. An alternative manufacturing process is inevitably required which is capable of reducing the environmental impact during various phases of product life cycle that helps in cost saving by extending the service life of equipment or parts which will in turn greatly improve the country’s economy. The advanced remanufacturing techniques such as laser metal deposition (LMD) process that belongs to a class of additive manufacturing processes can overcome the limitations of conventional manufacturing processes and capable to repair engineered parts having complex features that are difficult to access at the repair site. LMD can be used to fabricate part directly from its three-dimensional (3D) computer-aided design (CAD) model just by adding materials layer by layer. This technology offers design flexibility to engineers by allowing modification of an existing design without having to start from the scratch which is a basic requirement in product remanufacturing . This chapter discusses the capability of LMD process for restoring and remanufacturing high-valued components back to their perfect working conditions. Some of the research works that demonstrate the capability and effectiveness of using LMD for remanufacturing of high-valued products that is sustainable, cheap, and above all energy efficient are briefed. A case study to demonstrate the metallurgical integrity and properties of titanium alloy powder deposited on Ti6Al4V substrate using the LMD process and its sustainable aspects is also discussed in this chapter.

Processing Parameters Influence on Wear Resistance Behaviour of Friction Stir Processed Al-TiC Composites

Friction stir processing (FSP) being a novel process is employed for the improvement of the mechanical properties of a material and the production of surface layer composites. The vital role of the integrity of surface characteristics in the mechanical properties of materials has made the research studies into surface modification important in order to improve the performance in practical applications. This study investigates the effect of processing parameters on the wear resistance behavior of friction stir processed Al-TiC composites. This was achieved through microstructural characterization by using both the optical and scanning electron microscope (SEM), microhardness profiling, and tribological characterization by means of the wear. The microhardness profiling of the processed samples revealed an increased hardness value, which was a function of the TiC particles incorporated when compared to the parent material. The wear resistance property was also found to increase as a result of the TiC powder addition. The right combination of processing parameters was found to improve the wear resistance property of the composites produced.

Areas of Application of Laser Metal Deposition Process–Part Repair and Remanufacturing

Laser metal deposition process is an important additive manufacturing process with a number of capabilities such as the ability to fabricate three dimensional (3D) part directly from the 3D computer aided design profile of the part; the ability to repair worn out parts of very high value that were not repairable in the past; and the ability to build a new part on an existing part that are metallurgically bonded to the old part. This important capability of the laser metal deposition process (ability to add new part on an existing part) is what has positioned this important additive manufacturing process in product remanufacturing and this is a unique laser metal deposition capability. Product remanufacturing is an important aspect of manufacturing that helped to improve material life cycle and helped to reduce scrap. In this chapter, repair, remanufacturing and surface modification applications areas of laser metal deposition process are presented.

Future Research Direction in Functionally Graded Materials and Summary

Functionally Graded Materials (FGMs) are a class of advanced engineered materials characterized by a variation in composition or/and a variation in microstructure, with a corresponding variation in properties, such as the mechanical, the thermal, and the electrical properties. The main aim of FGM is to eliminate the sharp interface that is present in the conventional composite materials, where failure mostly begins because of the high stress concentration at this site. The sharp interface is replaced with the gradual variation of composition, as well as the microstructural composition through the non-uniform distributions of the reinforcement phase (s) dispersed gradually, according to their position in the structure. The functionally graded material (FGM) was initially developed for a thermal barrier application, but with the new developments in the industries and modern fabrication processes, the application areas have increased substantially. Such application areas now include those for the general use as structural components in extreme working environments, such as high-temperature and high-pressure environments. Functionally graded material is one of the most efficient materials in achieving sustainable development in industries. In this chapter, the future research requirements for FGMs are presented, together with an extensive summary of this book.

Effect of laser power and powder flow rate on dilution rate and surface finish produced during laser metal deposition of Titanium alloy

The influence of processing parameters on the resulting properties of laser metal deposition process cannot be overemphasized. In this research, the influence of laser power and powder flow rate on the dilution and surface roughness value produced are critically studied‥ The laser power was set between 1.8 kW and 3.0 kW, while the powder flow rate was set between 2.88 and 5.76 g/min. The scanning speed and the gas flow rate were maintained at constant values of 0.05m/s and 4l/min respectively. The study revealed that, as the laser power was increased, the degree of dilution increases but the average surface roughness value decreases. Also, as the powder flow rate was increased, the dilution decreases and the average surface roughness increases. The study shows that it is important to keep the powder flow rare low so as to achieve a better surface finished and also not to use too high laser power as this will result in higher dilution, which is not desirable in the laser additive manufacturing process because it will affect the dimensional accuracy of the part under processing.

Introduction to Advanced Cutting and Joining Processes

Traditional cutting processes are becoming obsolete in many modern applications because of their limitations or prohibitive to use or as a non-viable option for such modern applications. Conventional cutting processes such as turning and milling have become non-economical cutting processes for most of the advanced engineering materials that are developed to be high performing due to the nature of applications they are intended for. Most of these materials interact with the cutting tool in such a way that the cutting tools are consumed more rapidly during the cutting process that increases the downtime and increases the cost of manufacturing or they can even destroy the material make-up, most especially advanced composite materials. Difficult-to-machine materials are costly to machine using these traditional machining processes. In view of the aforementioned problems, the need for advanced machining processes became imperative. Also, the machines and devices are now designed to become smaller than they used to be. The need to reduce global warming is another driving force for the development of advanced machining processes. The constant strive to make moving and flying machines such as automobile and aerospace smaller and more compact is one of the requirements to reduce global warming. There is need to have a cutting process that is able to machine materials with high accuracy and at micro- and nanoscale levels. Joining these advanced materials as well as joining of materials at micro- and nanoscale levels is inevitable because at one point or the other, materials are joined during fabrication processes. Conventional welding processes could not be used to join these advanced and micro- and nanoscale materials because of large heat-affected zone that is associated with this welding processes. Also, the tools used in most of these conventional welding processes are even larger than the workpiece. Contact-less machining and welding processes are desired to be able to efficiently and effectively machine and join these high-technological materials. The section A of this book deals extensively with the various advanced non-contact, and tool-less machining processes such as laser machining, water jet machining and chemical machining. Non-contact joining processes are dealt with in great detail in section B of this book which include laser welding, ultrasonic welding and explosive welding processes. In this chapter, a brief introduction of these advanced machining and joining processes is presented.

Laser Metal Deposition of Composites and Functionally Graded Materials

This chapter deals with the fabrication of composites materials consisting of metals and ceramic or metal-metal composite materials. The flexibilities offered by the laser metal deposition process allow the use of more than one material at the same time during the deposition process. This important process makes it possible to fabricate parts with two dissimilar materials which could be difficult to produce with any other manufacturing process. Functionally graded materials can also be produced with laser metal deposition process. A number of composite materials and functionally graded materials produced using the laser metal deposition process has been investigated and reported in the literature. Laser metal deposition process are also used to produce composite coatings and functionally graded material coatings on other material in order to improve the surface property of such base materials. Some of these studies are presented in this chapter. The properties of these laser deposited composite materials and functionally graded materials are also presented.