EFFECT OF LASER BEAM RADIATION ON FATIGUE CRACK PROPAGATION IN AISI 4150 STEEL

1998 ◽  
Vol 21 (12) ◽  
pp. 1549-1558 ◽  
Author(s):  
Tsay ◽  
Lin
2014 ◽  
Vol 783-786 ◽  
pp. 2310-2315 ◽  
Author(s):  
Nikolai Kashaev ◽  
Stefan Riekehr ◽  
Manfred Horstmann ◽  
Volker Ventzke

Weight reduction is the main driving force in automotive and aircraft structural design. As a result, magnesium alloys, with their high potential for lightweight construction, have attracted a considerable amount of industrial attention. The determining criterion for the structural applications of magnesium alloys is the availability of efficient joining technologies for the construction of lightweight structures and the availability of reliable data for the assessment of their damage tolerance behaviour. Laser beam welding (LBW), as a high-speed and easily controllable process, allows the welding of complex geometric forms that are optimised in terms of mechanical stiffness, strength, production velocity and visual quality. The work accomplished in this study addresses the challenges of the LBW process for typical joint configurations using the magnesium alloy AZ31HP: butt joints, T joints and overlap joints. LBW processes were developed for use with a 3.3-kW Nd:YAG laser to optimise the mechanical performance of such joints with respect to tensile strength, fatigue, fatigue crack propagation and mechanical fracture behaviour. The relationships between the LBW process and the microstructural and mechanical properties of welds were established. Compared to state-of-the-art aerospace alloys, AZ31HP demonstrates that magnesium alloys have potential for use in structural applications, with AZ31HP being comparable to AA2024T351 and AA6061T6. Welded AZ31HP exhibits better crack resistance than the base material, so fully welded integral structures made from magnesium alloys can be used in lightweight construction.


2014 ◽  
Vol 891-892 ◽  
pp. 1457-1462 ◽  
Author(s):  
Nikolai Kashaev ◽  
Sergey Chupakhin ◽  
Josephin Enz ◽  
Volker Ventzke ◽  
Anne Groth ◽  
...  

To meet the future demands of the aerospace industry with respect to safety, productivity, weight, and cost, new materials and joining concepts have being developed. Recent developments in the metallurgical field now make it possible to use laser-weldable Al-alloys of the 2xxx series such as AA2198 with a high structural efficiency index due to their high strength and low density. AA2198 holds the promise of providing a breakthrough response to the challenges of lightweight design in aircraft applications. Laser beam welding as an efficient joining technology for fuselage structures is already established in the aircraft industry for lower fuselage panels because the welded panels provide a higher buckling strength and lower weight compared with the classical riveted designs. The key factor for the application of laser-welded AA2198 structures is the availability of reliable data for the assessment of their damage tolerance behavior. In the research presented, the mechanical properties with regard to fatigue and fatigue crack propagation of laser beamwelded AA2198 joints and four-stringer panels were investigated. It was found that the fatigue endurance limit of laser beamwelded AA2198T3 is approximately 25 % below the endurance limit of the base material. With regard to the fatigue crack propagation behavior, the laser beam welded four-stringer panels with T-joints show a fatigue life increased by a factor of 1.7 compared with the base material. This work shows that high-quality laser beam welds of AA2198 can be produced on a large scale using the laser beam welding facilities of the Helmholtz-Zentrum Geesthacht.


2014 ◽  
Vol 52 (4) ◽  
pp. 283-291 ◽  
Author(s):  
Gwan Yeong Kim ◽  
Kyu Sik Kim ◽  
Joong Cheol Park ◽  
Shae Kwang Kim ◽  
Young Ok Yoon ◽  
...  

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