Material flow in variable polarity plasma arc keyhole welding of aluminum alloy

A 7075 aluminum alloy was successfully welded by pulsed variable polarity plasma arc welding (PVPPAW) and the single-stage aging behavior of the 7075 aluminum alloy PVPPAW joint was systematically investigated. The results demonstrated that the tensile strength of the welded joints initially increased and then decreased with the increase of the single-stage aging temperature and time. After single-stage aging at 490 °C for 80 min and at 130 °C for 24 h, the tensile strength of the welded joint was 551 MPa, which was increased by 38.5% compared to the as-welded joint. Moreover, the conductivity was 25% international annealed copper standard (IACS) at room temperature, and the resistance to stress corrosion was improved. The main strengthening phases of the weld center were η′ and η phase. The average precipitate size slightly increased with the increase of the single-stage aging temperature, but no obvious change was observed with the increase of the single-stage aging time. The area fraction was initially increased and then decreased with the increase of the single-stage aging temperature and time.

Download Full-text

VARIABLE POLARITY PLASMA ARC WELDING PROCESS FOR THICK ALUMINUM ALLOY

Journal of Mechanical Engineering ◽

10.3901/jme.2006.09.144 ◽

2006 ◽

Vol 42 (09) ◽

pp. 144 ◽

Cited By ~ 3

Author(s):

Yongquan HAN

Keyword(s):

Aluminum Alloy ◽

Arc Welding ◽

Welding Process ◽

Plasma Arc Welding ◽

Plasma Arc ◽

Variable Polarity ◽

Arc Welding Process ◽

Variable Polarity Plasma Arc

Download Full-text

Prediction of the Weld Pool Stability by Material Flow Behavior of the Perforated Weld Pool

Materials ◽

10.3390/ma13020303 ◽

2020 ◽

Vol 13 (2) ◽

pp. 303

Author(s):

Ruiqing Lang ◽

Yongquan Han ◽

Xueyu Bai ◽

Haitao Hong

Keyword(s):

Weld Pool ◽

Material Flow ◽

Flow Behavior ◽

Maximum Velocity ◽

Plasma Arc ◽

Mechanical Coupling ◽

Arc Pressure ◽

Variable Polarity ◽

Weld Pools ◽

Variable Polarity Plasma Arc

This article presents the application of a computational fluid dynamics (CFD) finite volume method (FVM) model for a thermo-mechanical coupling simulation of the weld pool used in variable polarity plasma arc welding (VPPAW). Based on the mechanism of the additional pressure produced through self-magnetic arc compression and the jet generated from mechanical plasma arc compression, and considering the influence of arc height and keyhole secondary compression on arc pressure, a three-dimensional transient model of variable polarity plasma arc (VPPA) arc pressure was established. The material flow behaviors of the perforated weld pools were studied. The results show that three kinds of flow behavior existed in the perforation weld pools and it is feasible to predict the weld pool stability by the material flow behaviors of the perforated weld pools. The weld pools can exist stably if the material flow in the bottom of the perforated weld pools can form confluences with moderate flow velocities of 0.45 m/s, 0.55 m/s and 0.60 m/s. The weld pools were cut when the material flowed downward and outward with the maximum velocity of 0.70 m/s, 0.80 m/s. When the maximum material flow velocity was 0.40 m/s, the weld pool collapsed downward under the action of larger gravity. The thermo-mechanical coupling model was verified by the comparison of the simulation and experimental results.

Download Full-text

Physical mechanisms of fluid flow and joint inhomogeneity in variable-polarity plasma arc welding of thick aluminum alloy plates

Physics of Fluids ◽

10.1063/5.0058843 ◽

2021 ◽

Vol 33 (8) ◽

pp. 087103

Author(s):

Bin Xu ◽

Shinichi Tashiro ◽

Manabu Tanaka ◽

Fan Jiang ◽

Shujun Chen

Keyword(s):

Aluminum Alloy ◽

Fluid Flow ◽

Arc Welding ◽

Plasma Arc Welding ◽

Plasma Arc ◽

Physical Mechanisms ◽

Variable Polarity ◽

Variable Polarity Plasma Arc

Download Full-text

On-line monitoring of the keyhole welding pool in variable polarity plasma arc welding

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/095440502760291817 ◽

2002 ◽

Vol 216 (9) ◽

pp. 1265-1276 ◽

Cited By ~ 7

Author(s):

H Wang ◽

R Kovacevic

Keyword(s):

Arc Welding ◽

Plasma Arc Welding ◽

Plasma Arc ◽

Ann Model ◽

Image Processing Algorithm ◽

Welding Pool ◽

Keyhole Welding ◽

Variable Polarity ◽

Close Relationship ◽

Variable Polarity Plasma Arc

This paper presents a technique to monitor the weld penetration in real time by the front-side image sensing of the keyhole welding pool in variable polarity plasma arc welding (VPPAW) of a 6061 aluminium alloy. A novel optical system is developed to acquire the keyhole welding pool images from two sides of the plasma arc welding torch. The geometric sizes of the visible keyhole can be accurately obtained by using the developed image-processing algorithm. The variation in sizes of the visible keyhole has a close relationship with the real diameter of the keyhole. An artificial neural network (ANN) model is established to describe the relationship between the keyhole diameter and the geometrical sizes of the keyhole welding pool obtained from the image.

Download Full-text