Formation and influence mechanism of keyhole-induced porosity in deep-penetration laser welding based on 3D transient modeling

Lu, Fenggui; Li, Xibin; Li, Zhuguo; Tang, Xinhua; Cui, Haichao

doi:10.1016/j.ijheatmasstransfer.2015.07.041

Cited by 96 publications

(25 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Since the pores are irregular in shape and mostly sized over 50 μm, this suggests the presence of keyhole pores [24,25] that form when there is a keyhole instability. There are several reasons that may cause the formation of keyhole instabilities such as high cooling rate, insufficient ED, improper laser offset at the power bed [26].…”

Section: Resultsmentioning

confidence: 99%

Is the energy density a reliable parameter for materials synthesis by selective laser melting?

Prashanth

Scudino

Maity

et al. 2017

Materials Research Letters

322

104

View full text Add to dashboard Cite

The effective fabrication of materials using selective laser melting depends on the process parameters. Here, we analyse the suitability of the energy density to represent the energy transferred to the powder bed, which is effectively used to melt the particles and to produce the bulk specimens. By properly varying laser power and speed in order to process the powder at constant energy density, we show that the equation currently used to calculate the energy density gives only an approximate estimation and that hatch parameters and material properties should be considered to correctly evaluate the energy density. IMPACT STATEMENTAl-12Si SLM samples were fabricated at constant energy density. The laser power and laser scan speed combination variation was used to demonstrate the significant changes needed with energy density equation. ARTICLE HISTORY

show abstract

Section: Resultsmentioning

confidence: 99%

Is the energy density a reliable parameter for materials synthesis by selective laser melting?

Prashanth

Scudino

Maity

et al. 2017

Materials Research Letters

322

104

View full text Add to dashboard Cite

show abstract

“…Some crucial numerical points, as the simulation of the free boundary, are also presented. (An advantage of Eulerian methods is that the simulation can compute the keyhole collapsing and help to predicate defect formation such as porosity [56,44].) In conclusion, current best simulations take into account the multiple reflections of the laser, the heat transfers with liquid and gas flows, and the liquid/gas free boundary displacement.…”

Section: Resultsmentioning

confidence: 99%

[INVITED] An overview of the state of art in laser welding simulation

Dal

Fabbro

2016

Optics & Laser Technology

138

View full text Add to dashboard Cite

“…Therefore, the increase of preheating temperature can effectively improve the laser absorption rate of base metals. The shape of cross section is only affected by the heat input, which means that the shape will not change with the same heat input [25]. When the same laser welding parameters are applied, Metals 2019, 9, 870 5 of 13 the higher the preheating temperature, the larger the weld width is.…”

Section: Effect Of Preheating On the Cross-section Of Laser Welded Jomentioning

confidence: 99%

Effect of Preheating Temperature on Microstructure and Properties of 42CrMo4/38MnVS6 Heterogeneous Laser Welded Joint

Qiu

Xing

et al. 2019

Metals

View full text Add to dashboard Cite

Laser-welded forged steel pistons can meet the needs of the new era of heavy truck engines. 42CrMo4 and 38MnVS6 are widely used as piston materials due to the good mechanical properties. This study investigates the influence of preheating on microstructure and mechanical properties of 42CrMo4/38MnVS6 laser welding joint. The experimental results show preheating increases the laser absorption capacity of the metal, which can lead to an increase in weld width. The microstructure of weld is the high-hardness and poor toughness twin martensite without preheating. As the temperature of preheating increases, the twin martensite in the weld begins to transform into lath martensite and regenerates ferrite and bainite. As the preheating temperature increases, the plane fracture toughness (K1C) of the weld increases and then decreases, reaching the highest value of 2322.94 MPa·mm −1/2 at 150 • C. Compared with no preheating conditions, the tensile strength of the welded joint after preheating is improved. The fracture mode of welded joints changes from brittle fracture to ductile fracture. When the preheating temperature is 100-200 • C, the tensile strength of the welded joint reaches 1018.1-1032.5 MPa; when the preheating temperature is 250 • C-300 • C, the tensile strength decreases. the heat input is in the range of 275 J/mm 0.5 ·s 0.5 to 435 J/mm 0.5 ·s 0.5 , and there was no defect in the weld [12]. Kuryntsev et al. studied the effect of heat treatment on laser welded joints of 0.349C-1Cr-1Si steel. The results showed that the laser welded joint had the characteristics of high hardness and low elongation. After heat treatment, the elongation and ductility of the welded joint are improved [13]. Laser welding has a high energy density, and the base metal is not easy to deform after welding. It can optimize the piston structure and is conducive to the full combustion of fuel. Therefore, the development of laser welding forged steel piston has become one of the development directions of piston structure [14][15][16][17]. Preheating before welding can increase the laser absorption rate of the metal and reduce the cooling rate of the weld, adjust the stress distribution of the welded joint, avoid the generation of hardened structure in the weld, and is one of the welding methods to effectively improve the mechanical properties of the welded joint [18,19].At present, there are more studies on laser welding of aluminum alloy and low carbon steel with preheating, but less on medium carbon steel [20][21][22]. In this paper, the effect of preheating on the weld structure of 42CrMo4/38MnVS6 laser welding is studied, and the mechanical properties of welded joints under different preheating temperature are compared and analyzed, which provides the basis of experimental and theoretical for the application of laser welding technology in a forged steel piston. Materials and Methods Materials

show abstract

Formation and influence mechanism of keyhole-induced porosity in deep-penetration laser welding based on 3D transient modeling

Cited by 96 publications

References 34 publications

Is the energy density a reliable parameter for materials synthesis by selective laser melting?

Is the energy density a reliable parameter for materials synthesis by selective laser melting?

[INVITED] An overview of the state of art in laser welding simulation

Effect of Preheating Temperature on Microstructure and Properties of 42CrMo4/38MnVS6 Heterogeneous Laser Welded Joint

Contact Info

Product

Resources

About