Pore formation and its mitigation during hybrid laser/arc welding of advanced high strength steel

Atabaki, M. Mazar; Ma, Jingsen; Liu, W.; Kovacevic, Radovan

doi:10.1016/j.matdes.2014.10.072

Cited by 76 publications

(25 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Those pores generated due to improper welding parameters are ranked as processing pores, typically showing a nonspherical or irregular shape, as shown in Figure . Such cavities are mainly composed of metal vapor and shielding gas . The distribution of process‐induced gas pores is not symmetric inside the weld due to keyhole instability …”

Section: Experiments and Simulationsmentioning

confidence: 99%

“…Such cavities are mainly composed of metal vapor and shielding gas. 36 The distribution of process-induced gas pores is not symmetric inside the weld due to keyhole instability. 23,35,37 Note that a hybrid laser weld with processing pores is unacceptable in service because this type of porosity tends to be a cracking site in case of cyclic loading, as shown in Figure 4.…”

Section: Pore Type and Formationmentioning

confidence: 99%

See 1 more Smart Citation

Fatigue behaviors of laser hybrid welded AA7020 due to defects via synchrotron X‐ray microtomography

Song

Ding³

et al. 2019

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

Defect or shrinkage is known to have a detrimental effect on the fatigue resistance of casting lightweight alloys and additively manufactured or 3D printed materials. However, very few works focus on the damage mechanism of fusion welded Al alloys due to gas pores or metallurgical defects. This paper performs an investigation on the effect of porosity on the damage evolution of laser hybrid welded 7020‐T651 alloys. The critical pore size comparable with average weld grain was assumed in terms of the population and dimension of micropores. To characterize the coupling effect between gas pores and cracks, an in situ fatigue testing rig was developed to well work at the synchrotron radiation tomography system. Combining synchrotron X‐ray microtomography and fatigue resistance testing, the pore size and location were correlated with the crack initiation and crack growth path but relatively less on the long crack propagation rate. Furthermore, the interaction between the porosity and stress concentration was elucidated by using finite element simulations, which shows that the gas pore appears to be a preferred cracking site especially near the surface.

show abstract

Section: Experiments and Simulationsmentioning

confidence: 99%

Section: Pore Type and Formationmentioning

confidence: 99%

Fatigue behaviors of laser hybrid welded AA7020 due to defects via synchrotron X‐ray microtomography

Song

Ding³

et al. 2019

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

show abstract

“…However, the molten material would defocused the laser beam resulting in the keyhole collapse, and the presence of porosity in the weld should be expected ( It is reported that the incident laser beam intensity could be affected by many absorptions in the groove. The number of the reflections (n r ) into the keyhole and groove could be described by Equation (6) [29]:…”

Section: Tablementioning

confidence: 99%

Laser-based welding of 17-4 PH martensitic stainless steel in a tubular butt joint configuration with a built-in backing bar

Atabaki

Liu

et al. 2016

Optics & Laser Technology

View full text Add to dashboard Cite

Laser-based welding of thick 17-4 precipitation hardening (PH) martensitic stainless steel (SS) plates in a tubular butt joint configuration with a builtin backing bar is very challenging because the porosity and cracks are easily generated in the welds. The backing bar blocked the keyhole opening at the bottom surface through which the entrapped gas could escape, and the keyhole was unstable and collapsed overtime in a deep partially penetrated welding conditions resulting in the formation of pores easily. Moreover, the fast cooling rate prompted the ferrite transform to austenite which induced cracking. Two-pass welding procedure was developed to join 17-4 PH martensitic SS. The laser welding assisted by a filler wire, as the first pass, was used to weld the groove shoulder. The added filler wire could absorb a part of the laser beam energy; resulting in the decreased weld depth-to-width ratio and relieved intensive restraint at the weld root. A hybrid laser-arc welding or a gas metal arc welding (GMAW) was used to fill the groove as the second pass. Nitrogen was introduced to stabilize the keyhole and mitigate the porosity. Preheating was used to decrease the cooling rate and mitigate the cracking during laser-based welding of 17-4 PH martensitic SS plates.

show abstract

“…The increased transmitted energy led to an increase of the substrate melted zone area (A2). In addition, the increased laser power extended the lifetime of the molten pool, which further increased the area of the substrate melted zone (A2) [22][23][24]. Thus, the dilution rate increased according to Equation (1).…”

Section: Analysis Of Dilution Ratementioning

confidence: 99%

Investigation of Geometric Characteristics in Curved Surface Laser Cladding with Curve Path

Lian

Zhang

et al. 2019

Metals

View full text Add to dashboard Cite

Laser cladding on curved surfaces is essential in industrial applications for restoration and remanufacturing of high-value parts. This study investigated the influence of different factors on clad width, clad height, and dilution rate in curved surface laser cladding with curved path. Mathematical models were developed using central composite designs to predict these geometric characteristics by controlling laser power, scanning speed, gas flow, and altering the outside radius of the cylindrical substrate. Analysis of variance and response surface methodology indicated that clad width increased with increasing laser power and reducing scanning speed. Clad height positively correlated to laser power and negatively correlated to the outside radius of the cylindrical substrate. Increasing the laser power while decreasing the scanning speed led to an increase in dilution rate. Afterwards, the geometric characteristics of the clad were improved by optimizing these factors with the target to maximize clad width and height as well as to minimize dilution rate. The difference between model predictions and experimental validations for clad width, clad height, and dilution rate were 3.485%, 3.863%, and 6.566%, respectively. The predicted accuracy was verified with these models, and they were able to provide theoretical guidance to predict and control the geometric characteristics of curved surface laser cladding with a curved path.

show abstract

Pore formation and its mitigation during hybrid laser/arc welding of advanced high strength steel

Cited by 76 publications

References 24 publications

Fatigue behaviors of laser hybrid welded AA7020 due to defects via synchrotron X‐ray microtomography

Fatigue behaviors of laser hybrid welded AA7020 due to defects via synchrotron X‐ray microtomography

Laser-based welding of 17-4 PH martensitic stainless steel in a tubular butt joint configuration with a built-in backing bar

Investigation of Geometric Characteristics in Curved Surface Laser Cladding with Curve Path

Contact Info

Product

Resources

About