Determination of tensile strain causing solidification cracking in welding

Wire arc additive manufacturing, employing conventional fusion welding processes, shows excellent versatility and can therefore be used for structural modifications of existing parts to create hybrid components. This study evaluates the modification of cold-formed AA2024 metal sheets with 2xxx filler metals to produce 2xxx hybrid structures. The alloys are investigated by thermodynamic simulations and the solidification crack susceptibility is assessed by calculating the index for hot cracking susceptibility. Using cold metal transfer, single-layer depositions are generated on profile sheets after which the specimens are characterised by three analysis procedures: metallographic analysis, chemical analysis, and hardness testing. Results indicate that AA2024 wire material, although generally considered difficult to weld, is more suitable for the additive modification of AA2024 sheets and profiles, as crack-free specimens can be deposited on cold-formed substrates.

Section: Resultsmentioning

confidence: 88%

Characterisation of structural modifications on cold-formed AA2024 substrates by wire arc additive manufacturing

Silmbroth

Enzinger

Schneider-Bröskamp

et al. 2023

“…Strains or strain rates obtained from the tests are much more useful to use in theories or models proposed for solidification cracking. The importance of the strain rates has been emphasised by various studies [9,16,[21][22][23]30,31], especially the local strain rates [16,21,32]. In the present study, the susceptibility test results were given in terms of moving speed or deformation rate.…”

Section: Strain Rate Calculationmentioning

confidence: 99%

A new solidification cracking test: stationary weld-pool deformation test

Soysal

2021

Various tests have been proposed to assess solidification cracking susceptibility. A new solidification cracking test, called the stationary weld pool deformation test, is introduced in the present study. The test employs a stationary weld pool during testing, and it is conducted by joining two square small workpiece with spot gas tungsten arc welding and moving one piece away from the other one to cause cracking. The test has been applied on aluminium alloys 2024, 5083, 6061 and 7075, and the susceptibility of them was found consistent with literature. The fracture surface of some of these aluminium alloys were examined, and typical characteristics of solidification cracks were seen. Advantages and disadvantages of the test method were discussed.

“…Solidification cracking occurs in the mushy zone when a coherent interlocking columnar solid network separated by a continuous thin liquid film is ruptured by the tensile stresses due to obstructed solidification shrinkage and thermal contraction [108]. If a sufficient amount of liquid metal is present near the cracks, it can ‘backfill’ and ‘heal’ the incipient cracks.…”

Section: Solidification Crackingmentioning

confidence: 99%

Critical review on fusion welding of magnesium alloys: metallurgical challenges and opportunities

Pouranvari

2021

As the lightest structural alloys, magnesium alloys offer significant potential for improving the energy efficiency of various transportation systems. The lack of sufficient weldability of Mg alloys is a crucial barrier to their potential use in safety-critical applications. Porosity formation, grain structure engineering, solidification cracking, liquation, and liquation cracking are the key metallurgical challenges to obtain reliable and robust fusion welds in Mg alloys. This critical review highlights the current understating regarding controlling the metallurgical phenomena during fusion welding of Mg alloys and discusses the unresolved metallurgical challenges to shed light on the path forward to enhance fusion weldability of Mg alloys.