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The influence of two different weld imperfections (gap/crack) on the fatigue behaviour of spot welded joints was tested
Surface cracks havenoinfluenceon thefatiguelife
Samples with cracks in the electrode indentation /HAZ where tested
Stiffness curves are not significantly influenced by surface cracks
3D FE-Simulation demonstrate no changes of stress due to surface imperfections
Drop-out of molten material was avoided by EM pressure
Compensation of the hydrostatic pressure of up to 20 mm thick
aluminum and stainless steel (experiment and FEM)
Mitigation of the weld bead dynamics
Significant changes in the velocity distributions in the weld pool
Weld pool geometry shape changes due to Hartmann effect
Significant porosity reduction
Surface quality improvements
Drop-out of molten material was avoided by EM pressure
Compensation of the hydrostatic pressure of up to 20 mm thick
aluminum and stainless steel (experiment and FEM)
Mitigation of the weld bead dynamics
Significant changes in the velocity distributions in the weld pool
Weld pool geometry shape changes due to Hartmann effect
Significant porosity reduction
Surface quality improvements
Laser-GMA-hybrid welding of longitudinally welded large-diameter pipes of grades API- X80/ X120
(2015)
Potentials of the hybrid laser arc welding processes were investigated regarding reliable production of longitudinal welds of high strength pipe steels X80 and X120
Hybrid laser arc welding of the root pass:
Significant reduction in the weld cross section – savings of filler material
Lower heat input into the base material - improvement of mechanical properties of the weld joint
The arc type does not have any influence on the character of dilution in the laser part of the hybrid weld
14 mm deep root face was considered as optimum. No penetration of the filler material could be detected beyond this depth limit
Metal powder filler wires, micro alloyed with Ni and partly with Cr and Mo, guaranteed sufficient Charpy impact toughness at low temperature for the both investigated materials:
Hybrid laser arc welding is a very efficient process for the root pass in multi-pass welding and opens a large technical and economic potential for the manufacture of large pipes
Experimental study and numerical simulation of hot crack formation for novel laser weldability test
(2015)
Hot cracking susceptibility in laser beam welding was assessed for several stainless steels by means of the CTW test
The strain rate has a significant influence on the formation of the hot crack
It was possible to determine the critical strain and strain rate that led to shot crack formation
A material ranking of hot cracking resistance could be made.A three-dimensional FEM using the contact element technique to simulate hot cracking during LBW under external load conditions was developed.
Good agreement between the strain field measured using the DIC technique and the simulation results
Susceptibility to hot cracking can be predicted by using FEM with the correct mechanical and thermo-physical material properties
Test procedure to characterize the cracking susceptibility of RSW-steels has been developed
During externally loaded test procedure all investigated steels (HDT780CD+Z100, HDT780C+ZE75/75, HX340LAD+Z100, HCT690TD+Z100) showed a cracking behavior
With increased specimen load, the crack length grows for the micro-alloyed-steel and TRIP-steel
Complex phase steels behavior during test procedure:
Crack length growth with increasing force could not be determined
The cracking susceptibility of electro-galvanized steels is less than hot-dip galvanized steels (in this case)
30
•Main Welding Technologies in the Automotive: RSW and laserbeam welding
•Light Weight Design leads to increasing use of AHSS and UHSS which results in higher demands for the joining technology
•Joining Multi-Material Structures offers opportunities for “new” Thermal-Mechanical Joining Processes and Hybrid Processes
•In the coming years a trend towards sustainable manufacturing can be seen. Comparison between laserbeam and RSW will be a tight match!
High power laser welding technology has made a large progress in the last decade and established itself in different industrial applications;
Hybrid laser arc welding is one of the most prospective technologies for heavy components assembling;
Modern high speed video observation, in situ x-ray screening as well as simulation techniques contributed to better understanding of laser welding process;
New approaches e.g. application of electromagnetic fields for melt pool control and welding at reduced pressure ambient have significantly contributed to extending the process boundaries far beyond the known Limits.
The influence of two different weld imperfections (gap/crack) on the fatigue behaviour of spot welded joints was tested
Surface cracks have no influence on the fatigue life
Samples with cracks in the electrode indentation /HAZ where tested
Stiffness curves are not significantly influenced by surface cracks
3D FE-Simulation demonstrate no changes of stress due to surface imperfections
•
Welding under external forces was found suitable for characterizing AHSS materials
New quick and easy-to-perform procedure for establishing a material ranking regarding cracking susceptibility
1. Steel Production and Processing in Europe
2. Design Trends in the Automotive Industry
3. Welding Technologies in the Automotive Industry
4. Problems while Processing AHSS/UHSS
5. Challenges in Joining Multi-Material Structures
6. Mechanical Joining Technologies
7. Thermal-Mechanical Joining Processes
8. Energy Efficiency of Welding Processes