Mutiu F. Erinosho

Influence of processing parameters on laser metal deposited copper and titanium alloy composites

Abstract The laser metal deposition (LMD) was conducted on copper by varying the processing parameters in order to achieve the best possible settings. Two sets of experiments were conducted. The deposited composites were characterized through the evolving microstructure, microhardness profiling and mechanical properties. It was found that the evolving microstructures of the deposited composites were characterized with primary, secondary and tertiary arms dendrites, acicular microstructure as well as the alpha and beta eutectic structures. From the two sets of experiments performed, it was found that Sample E produced at a laser power of 1200 W and a scanning speed of 1.2 m/min has the highest hardness of HV (190±42) but exhibits some lateral cracks due to its brittle nature, while Sample B produced at laser power of 1200 W and a scanning speed of 0.3 m/min shows no crack and a good microstructure with an increase in dendrites. The strain hardening coefficient of the deposited copper composite obtained in this experiment is 3.35.

A review article: The mechanical properties and the microstructural behaviour of laser metal deposited Ti-6Al-4V and TiC composite

Titanium alloy (Ti-6Al-4V) Grade 5 has been regarded as the most useful alloy for the aerospace applications, due to their light weight properties. Today, laser technology is an energetic process in which the beam ejected can travel a longer distance and spot on the focused surface. The combination of metallic powder and laser beam has been used concurrently to form a solid figure. However, this combination has generated a permanently solidified metallurgical bonding between the laser-deposited metallic powders. Several research works have been conducted to improve the mechanical properties of the primary alloy, Ti-6Al-4V. This article conversely highlights the series of work that have been conducted on improving the mechanical properties and microstructures of the primary alloy with the addition of titanium carbide (TiC). The Ti-6Al-4V alloy has been widely selected in most critical part of a component. Their reinforcement with TiC composite particle has been achieved successfully through the optimal usage of laser technology. The characteristics of the reinforced component have vehemently improved the mechanical properties such as the tensile strength, wear resistance, fracture toughness and hardness; as well as the morphologies and phases of the microstructures.

STUDY ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF 304 STAINLESS STEEL JOINTS BY TIG–MIG HYBRID WELDING

Stainless steel is a family of Fe-based alloys having excellent resistance to corrosion and as such has been used imperatively for kitchen utensils, transportation, building constructions and much more. This paper presents the work conducted on the material characterizations of a tungsten inert gas (TIG)–metal inert gas (MIG) hybrid welded joint of type 304 austenitic stainless steel. The welding processes were conducted in three phases. The phases of welding employed are MIG welding using a current of 170A, TIG welding using a current of 190A, and a hybrid TIG–MIG welding with currents of 190/170A, respectively. The MIG, TIG, and hybrid TIG–MIG weldments were characterized with incomplete penetration, full penetration and excess penetration of weld. Intergranular austenite was created toward transition and heat affected zones. The thickness of the delta ferrite (δ-Fe) formed in the microstructures of the TIG weld is more than the thickness emerged in the microstructures of MIG and hybrid TIG–MIG welds. A TIG–MIG hybrid weld of specimen welded at the currents of 190/170A has the highest ultimate tensile strength value and percentage elongation of 397.72MPa and 35.7%. The TIG–MIG hybrid welding can be recommended for high-tech industrial applications such as nuclear, aircraft, food processing, and automobile industry.

Laser surface modification of Ti6Al4V-Cu for improved microhardness and wear resistance properties

To modify the properties of Ti6Al4V alloy, Cu has been added to host an antimicrobial effect in the revised alloy for marine application. The Laser Metal Deposition (LMD) process on the Ti6Al4V alloy and Cu was been investigated for surface modification in order to combat the problem of biofouling in the marine industry. The investigations focused on the microstructural observations, micro-hardness measurements and dry sliding wear in the presence of 3 and 5 weight percents of Cu. The microstructure results showed that Widmanstatten microstructures were formed in all the samples and lose their robustness towards the fusion zone as a result of the transition of heat sink towards the substrate. The microhardness values of Ti6Al4V-3Cu and Ti6Al4V-5Cu alloys were greatly improved to 547±16 VHN

Effect of laser power on the microstructural behaviour and strength of modified laser deposited Ti6Al4V+Cu alloy for medical application

The excellent biocompatibility property of Grade 5 titanium alloy has made its desirability largely increasing in the field of biomedical. The titanium alloy (Ti6Al4V) was modified with the addition of 3 weight percent (wt %) copper via a laser deposition process using the Ytterbium fiber laser with a wavelength of 1.047 μm. Therefore, this paper presents the effect of laser power on the microstructural behaviour and strength of the modified Ti6Al4V+Cu alloy. The laser powers were varied between 600 W and 1600 W respectively while all other parameters such as the scanning speed, powder flow rates and gas flow rates were kept constant. The melt pool and width of the deposited alloy increases as the laser power was increased. The α-lamella was observed to be finer at low laser power, and towards the fusion zone, Widmanstettan structures were fused and become smaller; and showing an evidence of α-martensite phases. The strength of the modified alloy was derived from the hardness values. The strength was observed to increase initially to a point as the laser power increases and afterwards decreased as the laser power was further increased. The improved Ti6Al4V+Cu alloy can be anticipated for biomedical application.

Effect of scanning speed and powder flow rate on the evolving properties of laser metal deposited Ti-6Al-4V/Cu composites

In laser metal deposition (LMD), good bonding between two similar or dissimilar materials can be achieved if the interrelationships between the processing parameters are well understood. LMD was conducted by varying the scanning speed and keeping other parameters constant. The deposited samples were characterised through the volume of the deposited composites, microstructure, microhardness and porosity. The effect of the optimised high powder flow rate and a constant power of 1,000 Watts led to a degree of porosity on the composites. The varying percentages of porosities in the samples which have an advance merit effect in the implantation of bones in animal and human were characterised. The Vickers microhardness was observed to increase with an increase in the scanning speed. At a low scanning speed, the microstructure appears coarse due to the high rate of deposition. The α-phase acicular microstructure decreases in size and thickness with an increase in the scanning speed.