scholarly journals Comparison of Hot Cracking Susceptibility of TIG and Laser Beam Welded Alloy 718 by Varestraint Testing

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 985 ◽  
Author(s):  
Pedro Alvarez ◽  
Lexuri Vázquez ◽  
Noelia Ruiz ◽  
Pedro Rodríguez ◽  
Ana Magaña ◽  
...  
Keyword(s):  
Grain Size ◽  
Laser Beam ◽  
Laser Beam Welding ◽  
Hot Cracking ◽  
Welding Parameters ◽  
Minor Effect ◽  
Alloy 718 ◽  
Material Source ◽  
Cross Sectional ◽  
Varestraint Test

Reduced hot cracking susceptibility is essential to ensure the flawless manufacturing of nickel superalloys typically employed in welded aircraft engine structures. The hot cracking of precipitation strengthened alloy 718 mainly depends on chemical composition and microstructure resulting from the thermal story. Alloy 718 is usually welded in a solution annealed state. However, even with this thermal treatment, cracks can be induced during standard industrial manufacturing conditions, leading to costly and time-consuming reworking. In this work, the cracking susceptibility of wrought and investment casting alloy 718 is studied by the Varestraint test. The test is performed while applying different welding conditions, i.e., continuous tungsten inert gas (TIG), low frequency pulsed TIG, continuous laser beam welding (LBW) and pulsed LBW. Welding parameters are selected for each welding technology in order to meet the welding quality criteria requested for targeted aeronautical applications, that is, full penetration, minimum cross-sectional welding width and reduced overhang and underfill. Results show that the hot cracking susceptibility of LBW samples determined by the Varestraint test is enhanced due to extended center line hot cracking, resulting in a fish-bone like cracking pattern. On the contrary, the minor effect of material source (wrought or casting), grain size and pulsation is observed. In fact, casting samples with a 30 times coarser grain size have shown better performance than wrought material.

scholarly journals Laser Weldability of Different Al-Zn Alloys and its Improvement

2015 ◽  
Vol 828-829 ◽  
pp. 389-394 ◽  
Author(s):  
Josephin Enz ◽  
Stefan Riekehr ◽  
Volker Ventzke ◽  
Nikolai Kashaev
Keyword(s):  
Laser Beam ◽  
Laser Beam Welding ◽  
High Strength ◽  
Hot Cracking ◽  
Welding Parameters ◽  
The Novel ◽  
New Approach ◽  
Application Range ◽  
Novel Approach ◽  
Zn Alloys

Weld defects - such as porosity and hot cracking - occur especially during the laser beam welding of high-alloyed Al-Zn alloys. This significantly limits the application range of these promising high-strength alloys. In the present study the laser weldability of different Al-Zn alloys was investigated regarding the used welding parameters and the chemical composition of the alloys. In addition, the novel approach of the Helmholtz-Zentrum Geesthacht for overcoming the weldability problems was applied to the different Al-Zn alloys in order to assess its capability. It was shown that the laser weldability of Al-Zn alloys deteriorates with an increasing amount of Zn, Mg and Cu. The variation of laser beam welding parameters did not lead to any improvement of weldability. Only the use of the new approach resulted in promising welding results even for the high-alloyed Al-Zn alloys.

Hot Cracking Susceptibility in Duplex Stainless Steel Welds

2018 ◽  
Vol 941 ◽  
pp. 679-685
Author(s):  
Kazuyoshi Saida ◽  
Tomo Ogura
Keyword(s):  
Stainless Steels ◽  
Laser Beam Welding ◽  
Austenitic Stainless Steels ◽  
Hot Cracking ◽  
Duplex Stainless Steels ◽  
Solidification Cracking ◽  
Solidification Mode ◽  
Gas Tungsten Arc ◽  
Varestraint Test ◽  
Super Duplex Stainless Steels

The hot cracking (solidification cracking) susceptibility in the weld metals of duplex stainless steels were quantitatively evaluated by Transverse-Varestraint test with gas tungsten arc welding (GTAW) and laser beam welding (LBW). Three kinds of duplex stainless steels (lean, standard and super duplex stainless steels) were used for evaluation. The solidification brittle temperature ranges (BTR) of duplex stainless steels were 58K, 60K and 76K for standard, lean and super duplex stainless steels, respectively, and were comparable to those of austenitic stainless steels with FA solidification mode. The BTRs in LBW were 10-15K lower than those in GTAW for any steels. In order to clarify the governing factors of solidification cracking in duplex stainless steels, the solidification segregation behaviours of alloying and impurity elements were numerically analysed during GTAW and LBW. Although the harmful elements to solidification cracking such as P, S and C were segregated in the residual liquid phase in any joints, the solidification segregation of P, S and C in LBW was inhibited compared with GTAW due to the rapid cooling rate in LBW. It followed that the decreased solidification cracking susceptibility of duplex stainless steels in LBW would be mainly attributed to the suppression of solidification segregation of P, S and C.

Joining of Aluminium Structures with Aluminium Foams

1998 ◽  
Vol 521 ◽  
Author(s):  
J. Burzer ◽  
T. Bernard ◽  
H. W. Bergmann
Keyword(s):  
Mechanical Properties ◽  
Laser Beam ◽  
Tensile Test ◽  
Laser Beam Welding ◽  
Welding Parameters ◽  
Transportation Industry ◽  
Absorption Properties ◽  
Testing Method ◽  
New Construction ◽  
Joining Process

ABSTRACTThe aim of this work is the evaluation of new construction elements for applications in transportation industry which are based on new designs incorporating commonly applied aluminium structures and aluminium foams. The work includes the characterisation of the joining process, the joining mechanism and the mechanical properties of the joining zone. A testing method for the joints is developed which is based on a common tensile test in order to evaluate the influence of the main laser welding parameters on the toughness of the joints and to afford a comparison between laser beam welding and gluing process. The analysis of the joining mechanism is investigated with the help of metallographic studies. In addition, the energy absorption properties of aluminium hollows filled and joined with foam structures are characterised.

Development of a novel optical measurement technique to investigate the hot cracking susceptibility during laser beam welding

2018 ◽  
Vol 63 (2) ◽  
pp. 435-441 ◽  
Author(s):  
N. Bakir ◽  
V. Pavlov ◽  
S. Zavjalov ◽  
S. Volvenko ◽  
A. Gumenyuk ◽  
...  
Keyword(s):  
Laser Beam ◽  
Measurement Technique ◽  
Optical Measurement ◽  
Laser Beam Welding ◽  
Hot Cracking

Developing laser beam welding parameters for the assembly of steel SLM parts for the automotive industry

2018 ◽  
Vol 24 (8) ◽  
pp. 1288-1295 ◽  
Author(s):  
Thiemo Valentin Fieger ◽  
Maximilian Ferdinand Sattler ◽  
Gerd Witt
Keyword(s):  
Laser Beam ◽  
Automotive Industry ◽  
Laser Beam Welding ◽  
Welding Parameters ◽  
Content Type ◽  
Steel Sheets ◽  
Novel Approach ◽  
Metal Sheets ◽  
Cold Rolled ◽  
Parameter Ranges

Purpose This paper aims to identify issues with joining selective laser melting (SLM) steels with conventional cold rolled steels through remote laser beam welding. Design/methodology/approach A novel approach for substituting conventional cold rolled metal sheets with SLM metal sheets, made of 316L and 18-Ni 300, is presented. The characteristics of the interaction of wrought and SLM materials are described, and joining benchmark parameters are presented and compared to known existing joining results. Finally, the joints are assessed in line with automotive specifications. This research also addresses the importance of joining technologies for the implementation of SLM as a full-fledged manufacturing technology for the automotive industry. Findings New parameter ranges for laser beam welding of SLM steels are defined. Research limitations/implications This research is limited to the examined steels and the used machines, parameters and equipment. Practical implications The presented benchmark parameters are expected to be useful for designers, product developers and machine operators. Originality/value Little knowledge is available about the behavior of SLM materials and their suitability for assembly processes. Novel information about SLM steels and their interaction with conventionally produced steel sheets is presented.

Developments and Trends in Laser Welding of Sheet Metal

2005 ◽  
Vol 6-8 ◽  
pp. 59-70 ◽  
Author(s):  
Frank Vollertsen
Keyword(s):  
Laser Beam ◽  
Sheet Metal ◽  
Spot Welding ◽  
Laser Beam Welding ◽  
Hot Cracking ◽  
Thick Sheet ◽  
Laser Systems ◽  
Thick Sheet Metal ◽  
Metal Welding ◽  
Remarkable Progress

There is some remarkable progress in laser beam welding of sheet metal which is driven by the advent of improved laser systems and process technologies. Here, potentials for reducing distortion and avoiding hot cracking are highlighted, and examples of current developments are given in the field of thin and thick sheet metal welding including spot welding of difficult-to-weld materials and material combinations.

The Effect of Laser Beam Welding Parameters onto the Evolving Joints Geometry

2017 ◽  
Vol 885 ◽  
pp. 178-183 ◽  
Author(s):  
Miklós Berczeli ◽  
Gábor Buza
Keyword(s):  
Laser Beam ◽  
Laser Welding ◽  
Feed Rate ◽  
Laser Beam Welding ◽  
Spot Size ◽  
Welding Parameters ◽  
Beam Focusing ◽  
Metallographic Cross Section ◽  
New Type ◽  
Beam Parameters

In our research the effect of a new type of laser beam parameters during the laser welding have been investigated with 80 different welding parameters. The laser welding parameters such as the laser power, laser beam spot size on the surface and feed rate greatly affect the resulting weld geometry. S235 grade steel has been used. The operating equipment was a Trumpf 4001 4 kW disk laser with a diameter of 100 microns optical fiber. The effect of different welding parameters were evaluated from the metallographic cross-section of the welded joints. This article describes the effect of the different laser beam focusing and the welding feed rate.

scholarly journals Weldability Evaluation of Alloy 718 Investment Castings with Different Si Contents and Thermal Stories and Hot Cracking Mechanism in Their Laser Beam Welds

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 402
Author(s):  
Pedro Álvarez ◽  
Alberto Cobos ◽  
Lexuri Vázquez ◽  
Noelia Ruiz ◽  
Pedro Pablo Rodríguez ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Laser Beam ◽  
Hot Cracking ◽  
Laves Phase ◽  
Hot Ductility ◽  
Alloy 718 ◽  
Weldability Tests ◽  
Cracking Mechanism ◽  
Haz Cracking ◽  
Si Content

In this work, weldability and hot cracking susceptibility of five alloy 718 investment castings in laser beam welding (LBW) were investigated. Influence of chemical composition, with varying Si contents from 0.05 to 0.17 wt %, solidification rate, and pre-weld heat treatment were studied by carrying out three different weldability tests, i.e., hot ductility, Varestraint, and bead-on-plate tests, after hot isostatic pressing (HIP) and solution annealing treatment. Onset of hot ductility drop was directly related to the presence of residual Laves phase, whereas the hot ductility recovery behaviour was connected to the Si content and γ grain size. LBW Varestraint tests gave rise to enhanced fusion zone (FZ) cracking with much more reduced heat-affected zone (HAZ) cracking that was mostly independent of Si content and residual Laves phase. Microstructural characterisation of bead-on-plate welding samples showed that HAZ cracking susceptibility was closely related to welding morphology. Multiple HAZ cracks were detected in nail or mushroom welding shapes, typical in keyhole mode LBW, irrespective of the chemical composition and thermal story of castings. In all LBW welds, Laves phase with a composition similar to the eutectic of the pseudo-binary equilibrium diagram of alloy 718 was formed in the FZ. The composition of this regenerated Laves phase matched with the continuous Laves phase film observed along HAZ cracks. This was strong evidence of backfilling mechanism, which is described as wetting and infiltration of terminal liquid along γ grain boundaries of parent material. The current results suggest that this cracking mechanism was activated in three-point intersections resulting from perpendicular crossing of columnar grain boundaries with fusion line and was enhanced by nail or mushroom weld shapes and narrow and columnar γ grain characteristics of castings. Neither Varestraint nor hot ductility weldability tests can reproduce this particular cracking mechanism.

scholarly journals Influence of Parameters of Laser Beam Welding on Structure of 2205 Duplex Stainless Steel

2019 ◽  
Vol 19 (1) ◽  
pp. 21-31 ◽  
Author(s):  
M. Landowski
Keyword(s):  
Stainless Steel ◽  
Laser Beam ◽  
Laser Welding ◽  
Duplex Stainless Steel ◽  
Welded Joints ◽  
Laser Beam Welding ◽  
Welding Parameters ◽  
Processing Technologies ◽  
High Level ◽  
The Impact

AbstractLaser welding is used in modern industry, having many advantages comparing to traditional welding technologies. Nowadays, industry sectors such as shipbuilding, automotive and aviation can’t be imagined without laser processing technologies. Possibility of increase of welded joint properties, autogenous welding and high level of process automation makes the technology of laser welding perspective part of the industry. Physical multidimensional processes complexity requires a deeper understanding of the impact of laser welding parameters on the quality of welded joints for industrial implementation. The paper presents results of microstructure investigations of laser beam welded stainless steel under various welding parameters. Welded joints was achieved by Ytterbium fiber laser type without the use of the filler material. Material for test was 2205 ferritic-austenitic duplex stainless steel (DSS) plates with thickness of 8 mm in delivery condition. The objectives of this research was to investigate influence of laser welding parameters on weld geometry of butt-welded joints. Investigations of bead shape revealed correlation between laser beam focus position and weld penetration depth.

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