Abstract
Stress relief treatments were carried out separately with a pneumatic chipping hammer, ultrasonic peening treatment, and heat treatment for metal active-gas welding (MAG) welded joints of 2205 duplex stainless steel. The effects of these methods on the residual stress, microstructure, mechanical properties and corrosion resistance of welded joints were studied. Results show the stress state of the weld and the surrounding area was effectively improved by the pneumatic chipping hammer and ultrasonic peening treatment, and the residual stress field of the surface layer changed from tensile stress to compressive stress. On the contrary, low-temperature stress relieving annealing had no obvious effect on stress distribution. After the pneumatic chipping hammer and ultrasonic peening treatment, the welded joints were machined and hardened. Correspondingly, strength and hardness were improved. However, the heat treatment only led to a slight decrease in strength and hardness due to the static recovery of the welded joint structure. All stress relief methods effectively improved the corrosion resistance of welded joints, with the ultrasonic peening treatment giving the best performance.
Highlights
As a third-generation duplex stainless steel (DSS), 2205 DSS is endowed with excellent welding performance, high toughness resulting from austenite, strong resistance to chloride corrosion and stress corrosion from ferrite [1,2,3]
High surface residual tensile stress will accelerate the failure of the workpiece and lead to the decline of fatigue life [18,19]
The values were 654 MPa and 636 MPa for specimen 3. Both the pneumatic chipping hammer and ultrasonic peening treatment are beneficial for diminishing tensile stresses
Summary
As a third-generation duplex stainless steel (DSS), 2205 DSS is endowed with excellent welding performance, high toughness resulting from austenite, strong resistance to chloride corrosion and stress corrosion from ferrite [1,2,3]. Welded joints made by MAG using the shielding gas 97% Ar + 3% N2 without the application of a magnetic field presented high resistance to general corrosion but high susceptibility to localized attack. Influences of stress removal methods on microstructures and performances were systematically studied for MAG welded joints of 2205 DSS. The pneumatic chipping hammer has been widely used in industrial production because of its simple operation In this process, hammer force, hammer frequency and hammer temperature have a great influence on the elimination of residual tensile stress of welded joints. A traditional stress-relieving heat treatment method is the experimental contrast The effects of these methods on the MAG welded joints of 2205 duplex stainless steel is significant, which can provide technical support for its industrial application
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