Venkata Suresh Bade, Srinivasa Rao P. and Govinda Rao P.
The purpose of this paper is to investigate the prominence of mechanical excitations at the time of welding. In the past years, the process of welding technology has expanded its…
Abstract
Purpose
The purpose of this paper is to investigate the prominence of mechanical excitations at the time of welding. In the past years, the process of welding technology has expanded its influence in manufacturing. The crucial drawback of conventional welding is prompted by internal stresses and distortions, which is the focal reason for weld defects. These weld defects can be diminished by the process called post-weld heat treatment (PWHT), which consumes more working hours and needs skilled workers. To replace these PWHT processes, mechanical vibrations are introduced during the process of welding to diminish these weld defects.
Design/methodology/approach
In the current research, the mechanical vibrations are transferred to weld-pool through vibro-motor and DC motor connected to the electrode. As per standards, the tensile test specimens were prepared for welding with different voltages of vibro-motor and DC motor respectively. The weld joints were tested for tensile strength and analyzed the microstructure at the fusion zone.
Findings
Melt-ability at fusion zone of 1018 mild steel was investigated by the single-stroke intense heat process of fusion welding. It is observed that the mechanical vibrations technique has a profound influence on the enhancement of the fusion zone characteristics and grain structure. The peak value of the tensile strength is observed at 100 s of vibration, 190 V of vibro-motor voltage and 18 V of electrode voltage. The tensile strength of the welded joints with vibrations is increased up to 22.64% when it is compared with conventional welding. The enhancement of the tensile strength of the weld bead was obtained because of the formation of fine grain structure. So, mechanical vibrations are identified as the most convenient method for improving the mild steel alloys weld quality.
Originality/value
A novel approach called mechanical vibrations during the process of welding is implemented for fusion zone refinement.
Details
Keywords
Venkata Suresh Bade, Srinivasa Rao P. and Govinda Rao P.
The purpose of this study is to explore the importance of vibrations during welding process. In recent years, welding has gained its supremacy in the field of production. The main…
Abstract
Purpose
The purpose of this study is to explore the importance of vibrations during welding process. In recent years, welding has gained its supremacy in the field of production. The main set back of the welding process is induced residual stresses, which is a major cause for many welding defects. These defects can be minimized by post-weld heat treatment methods, which is a time consuming and laborious process. In the recent past, a technique of exciting the weld-pool by vibrating the work-pieces was also adopted to minimize the above-mentioned stresses. A novel technique of electrode vibration is another effective way of transferring the vibrations to the weld-pool to influence the induced residual stress.
Design/methodology/approach
In this research, the electrode is vibrated with the help of an electric motor. The specimens were prepared as per American Society for Testing and Materials standards and welded with varying frequencies and voltages. The weldments are tested for hardness along the weld bead and heat affected zone, also the microstructure of the fusion zone is analyzed.
Findings
It is observed that there is an improvement in the hardness because of the grain refinement, which is a result of proper excitation of the weld-pool. It is observed that there is an improvement in hardness test up to 28.69% when compared with the conventional welding process. The peak value of hardness is observed at a frequency of 4,450 Hz. This is because of fine grain structure at this frequency, which is observed through the microstructure analysis.
Originality/value
A novel technique is introduced to refine the weld-pool through electrode vibrations. To improve the hardness of the welded joints, vibrations play a major role by refining the grain structure. The vibrations are imparted with the help of a special equipment attached to the electrode.
Details
Keywords
Shumank Deep, Thayaparan Gajendran, Marcus Jefferies, Venkata Suresh Uggina and Sanjay Patil
Research on strategic procurement was mostly focussed on the clients' and main contractors' perspectives, while limited work had been done from a subcontractor's perspective. The…
Abstract
Purpose
Research on strategic procurement was mostly focussed on the clients' and main contractors' perspectives, while limited work had been done from a subcontractor's perspective. The paper hypothesises that “strategic capability” influences the latent constructs of power, dependence and collaboration in the main contractor–subcontractor relationship. Therefore, the purpose of this study is to investigate the influence of a subcontractor's strategic capabilities on power, dependence and collaboration.
Design/methodology/approach
A survey questionnaire was developed and distributed amongst the subcontractors in Australia, and 212 complete responses were received. Then second order confirmatory factor analysis and partial least square structure equation modelling (PLS-SEM) analysis were performed to test the hypothesised relationships.
Findings
The findings support “strategic capabilities” as a construct expressive of a subcontractor's unique market position and good business reputation. The findings also suggest that strategically capable subcontractors enhance their potential for forming partnerships with main contractors through dependence (StratC. → Dep., β = 0.84; Effect Size (ES) = 0.713; p < 0.01), collaboration (StratC. → Collab., β = 0.84; ES = 0.697; p < 0.01) and bargaining power (StratC. → Pow., β = 0.83; ES = 0.672; p < 0.01).
Originality/value
The study is one of its kind to explore the impact of a subcontractor's strategic capability on their bargaining power, dependability and ability to form collaborations. Furthermore, results indicate that the “strategic capabilities” of subcontractors can strongly influence their ability to create “dependence”, foster “collaboration” and exert “power” over a main contractor. The findings can help improve the strategic procurement decision-making processes of both subcontractors and main contractors to build better business relationships.