Abstract
The core technique of electric storage water heaters is the manufacture of the tanks, and the welding technique is the key technology of the tank manufacture. A company producing water heaters received feedback from its after-sales that a large quantity of water leakage from the tanks was found in the market. A follow-up on the manufacturing site by the researchers showed that the position of the water leakage defects mostly happens in the welds of the tanks. Series of experiments were conducted to investigate the mechanical properties, residual stress, and diffusible hydrogen content of the longitudinal weld of the tank. Results of the mechanical properties showed that both the micro-hardness and the tensile strength of the welds are higher than the base metal. There are higher residual compressive stresses in the weld center and the adjacent-weld zone. Vertical residual compressive stress decreases first and then increases (149 MPa–28 MPa–134 MPa) from the weld ends to the middle, whilst the transversal stress decreases continuously (332 MPa~240 MPa) from the weld center to the heat affected zone. After enameling, the longitudinal welds’ peak micro-hardness of coarse grained region reduces by 30.9 HV1, and the average micro-hardness of the HAZ reduces by 5 HV1. The average vertical residual compressive stress difference of the same test points reduces from 270.6 MPa to 20.4 MPa. It proves that enameling can improve the mechanical property of the longitudinal welds.
Highlights
With the development of modern industry, more and more thin plate structures are used in manufacturing/production due to their light-weight and energy saving nature
Dias [20] et al analyze the residual stresses resulting from laser beam welding and plasma arc welding processes by X-ray diffraction technique, with sin2ψ method in Interstitial free (IF) steel butt joints
In order to prolong the life of the electric water heater, it is necessary to make the inner tank with higher manufacturing quality and better service performance
Summary
With the development of modern industry, more and more thin plate structures are used in manufacturing/production due to their light-weight and energy saving nature. There are a large number of non-uniform heat inputs resulting in the distribution of residual stress, which often produce adverse mechanical effects. Dias [20] et al analyze the residual stresses resulting from laser beam welding and plasma arc welding processes by X-ray diffraction technique, with sin2ψ method in Interstitial free (IF) steel butt joints. In order to prolong the life of the electric water heater, it is necessary to make the inner tank with higher manufacturing quality and better service performance. To achieve these capabilities, the key lies in the selection of bladder material and the manufacturing process of the bladder. The tensile strength and micro-hardness of the longitudinal joint are tested and the influence of enamel on the welding seam is analyzed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
