S. Senthil Kumaran

Effect of tube preparations on joint strength in friction welding of tube-to-tube plate using an external tool process

Several developments have been occurring in the field of materials processing, and friction welding is an important metal-joining process that has varied industrial applications. Friction welding of tube-to-tube plate using an external tool (FWTPET) is a vital friction welding process which is capable of producing leakproof high-quality weld joints. In the present study, FWTPET welds have been prepared with five different tube preparations. Liquid penetrant test (LPT) has been conducted in order to detect the occurrence of surface defects. Macro- and microstructural studies have been conducted and they reveal that improper weld configuration is susceptible to defect formation. Besides, hardness and tensile strength of five different tube preparations have been presented and analyzed. The present study leads to the production of defect free weld joints which have numerous industrial applications.

Eco-friendly aspects associated with friction welding of tube-to-tube plate using an external tool process

The competitiveness among the manufacturers has been forcing the manufacturing processes to be eco-friendly so as to deliver products with lesser impact on the environment, energy demand and other resources consumption. In this regard, this article presents the unique environmentally friendlier aspects associated with an innovative welding process namely friction welding of tube-to-tube plate using an external tool (FWTPET). This process is capable of generating robust weld joints with lesser energy consumption. A comparative analysis of FWTPET with conventional tungsten inert gas welding process has been narrated.

Suitability of friction welding of tube to tube plate using an external tool process for different tube diameters—A study

During the past few decades, the field of welding technology has been witnessing tremendous challenges. Welding is an important metal fabrication process that has high potential for industrial applications. Friction welding is a vital solid state joining process that has gained popularity in welding non-weldable alloys. Friction welding of tube to tube plate using an external tool (FWTPET) is an innovative friction welding process and it was invented in the year 2006. FWTPET is capable of welding tube to tube plate of similar or dissimilar metals and is capable of producing good-quality leak-proof weld joints. In this work, four different tube diameter conditions in FWTPET welding have been studied. Macrostructural and microstructural studies have been conducted and they reveal the weld configuration that is susceptible to defect formation. Hardness and tensile strength of four different tube diameter preparations have been analyzed. The present study leads to the production of defect-free weld joints which have numerous industrial applications.

Microstructure and mechanical properties of duplex stainless steels sintered in different atmospheres

Abstract Present investigation is aimed at developing duplex stainless steels through powder metallurgy route and study the effect of sintering atmospheres on density, mechanical properties and microstructures. Duplex stainless steel composition was prepared from the mixture of 316L and 430L alloyed powders. The powders were mixed in a pot mill for 12 h and compacted at a pressure of 560 MPa. The green compacts were sintered at 1350°C in four different atmospheres such as nitrogen, argon, hydrogen and partial vacuum. Sintered duplex stainless steels were subjected to density measurement, metallography examinations and tensile testing. Duplex stainless steel sintered in partial vacuum showed highest densification of 96% theoretical, tensile strength and ferrite content, when compared with stainless steels sintered in other three atmospheres. Microstructure of stainless steels sintered in argon, hydrogen and partial vacuum showed the bi-phase structure. SEM fractographs of the stainless steels sintered in partial vacuum and hydrogen revealed completely ductile mode of failure.

FWTPET Investigation on SA213 Tube to SA387 Tube Plate

In this research work, an experimental investigation of Friction Welding of Tube to Tube Plate with External Tool (FWTPET) has been carried out using backing block arrangement with interference fit. The Materials have been used in this research of SA213 tube and SA387 tube plate. The results of the experimental investigation revealed that by employing backing block, FWTPET is capable of producing defect free welds. The Welding sample has been conducted several characteristics such as Compression test, radiographic test and Microscopic Test. Further Taguchi L9 orthogonal array was utilized to find the most significant control factors which will yield better joint strength. Besides, the contribution of each process parameter has been determined using statistical analysis of variance (ANOVA). The Input and Output values are 1320 rpm Speed, 0 mm projection, 0.1 mm Depth of cut and 3086.90 MPa optimal joint strength respectively.

Effect of Milling on Sintering Behavior of γ-TiAl by Spark Plasma Sintering

In this study, densification behavior of mechanically alloyed TiAl powders by spark plasma sintering has been analyzed. TiAl alloy with a composition of TiAl-xNb-1Cr-0.4Mo-0.1B (x = 0, 3.5, 6, 8.5) was prepared by mechanical milling for 20 hrs and was consolidated by spark plasma sintering. Average particle size of 20 hrs milled powders was 5 µm and morphology of these milled powders was flaky. Density of these sintered samples varied from 99.1% to 99.8% of the theoretical density. The addition of Nb increases the densification of TiAl intermetallic compounds. The increase in densification of these milled TiAl powders has been related to the effects of milling such as decrease in particle size and morphological changes.

Development of amorphous and TiAl-Nb2Al intermetallic nanocomposite powders by mechanical alloying

Present investigation was focused on to synthesize TiAl-Nb2Al nanocomposite powders by high energy ball milling from a mixture of prealloyed TiAl, niobium, aluminium and SiC powders. Systems chosen with different Nb and Al concentrations were processed at optimized ball milling parameters. The synthesized powders were characterized with the help of X-ray diffraction (XRD), electron microscopy, differential thermal analysis (DTA) to understand the milling behaviour of TiAl / TiAl-Nb-Al-SiC systems. High energy ball milling of prealloyed TiAl powder resulted nanocrystalline structure at early time intervals (10hrs) and sustained up to 50hrs. TiAl-Nb-Al-SiC systems exhibited amorphous structure in lower Nb content and formation of Nb2Al nanocrystalline compound with increasing Nb and Al additions. Stability of TiAl covalent bonded intermetallic compound was weakened by dissolution of Nb in the matrix and resulted amorphous structure. The final product contained nanocrystalline TiAl, amorphous structure and TiAl-Nb2Al intermetallic nanocomposite powders with varying Nb and Al concentrations.

Garnet and Al-flyash composite under dry sliding conditions

The dry sliding wear behaviour of LM 24 aluminum alloy composites reinforced with garnet particles was evaluated. Stir casting technique was used to fabricate the composites. A pin-on-disc wear-testing machine was used to evaluate the wear rate, in which an EN 24 steel disc was used as the counterface. Results indicated that the wear rates of the composites were lower than that of the matrix alloy and further decreased with the increase in garnet content. However, in both unreinforced and reinforced composites, the wear rate increased with the increase in load and the sliding speed. Increase in the applied load increased the wear severity by changing the wear mechanism from abrasion to particle cracking-induced delamination wear. It was found that with the increase in garnet content, the wear resistance increased monotonically. The observations have been explained using scanning electron microscopy analysis of the worn surfaces and the subsurface of the composites. In this work, the most influencing input and output parameters have been performed and the process parameters have been prioritized using genetic algorithm. Genetic algorithm is used to optimize the most influencing input as well as output process parameters. The practical significance of applying genetic algorithm to dry sliding wear behavior process has been validated by means of computing the deviation between predicted and experimentally obtained wear behavior of metal matrix composite.

An Optimization of Erosive Wear on AA 2618 Reinforced with SI3N4, AlN and ZrB2 In Situ Composites

In this investigation, AA 2618 is taken as the matrix material and Si3N4 (Silicon Nitride), AlN (Aluminium Nitride) and ZrB2 (Zirconium Boride) are taken as the reinforcement material. The reinforcements are mixed with the matrix in various X weight percentages (wt %) (X=0, 2, 4, 6, 8) by stir casting method. According to the ASTM standard AA 2618 composites were prepared with various wt % to find the mass loss in erosion test. The samples were imposed with various input conditions to obtain minimum mass loss for AA 2618 composites. Taguchi method was used to find the maximum influenced process parameter for mass loss and ANOVA (Analysis of Variance) method was adopted for finding the percentage of contribution of each process parameters

Structure-Property Correlation of Rolled ZM21/Al Magnesium Macrocomposite

Cast magnesium alloys are resulting coarse grained structure and micro porosity. In order to improve the formability and ductility in magnesium alloy, it is planned to incorporate aluminum wires as reinforcement through extrusion. In the present paper, ZM21/Al macrocomposites were fabricated by direct co-extrusion process. The extrusion was carried at 450°C with the extrusion ratio of 25:1. Metallurgical bonding of ZM21 magnesium alloy and aluminum was studied with the help of optical metallography and hardness testing. It was observed a white interface layer (intermetallic) formed in between magnesium alloy and aluminum. The same was confirmed by hardness test and SEM-EDS test. The co-extruded macrocomposite was again processed with unidirectional rolling and cross rolling to improve the bonding and grain refinement of the alloy. The composite was rolled at 250°C for 75% reduction in thickness. The microstructure and hardness of the rolled composite were characterized.