User:FuzzyMagma/Liquation cracking

Liquation or solidification cracking is a type of cracking that occurs during the cooling process of certain types of alloys. It is caused by the liquidation of one phase before the other during cooling and can result in localized melting at grain or other boundaries, combined with the thermal strains associated with welding. Liquation cracking can be prevented or reduced by assessing the risk beforehand and controlling the welding parameters during the welding process.

Liquation cracking is a type of cracking that can occur in certain types of alloys during welding, particularly those that contain multiple phases with different melting points. It is caused by the liquidation of one phase before the other during the cooling process. The cracking can occur in the partially melted zone during the solidification of the liquated material. Liquation cracking can be caused by the melting of low melting-point grain boundary constituents which lead to small micro-cracks. These micro-cracks may not prove to be a serious problem, providing that they do not provide sites for more serious cracks to occur. Techniques such as residual stress analysis and microstructural characterization can be used to investigate the causes of liquation cracking. It is important to choose materials with a lower solidification gradient to avoid susceptibility to solidification cracking.

https://app.aws.org/wj/supplement/wj0204-50.pdf

http://s3.amazonaws.com/WJ-www.aws.org/supplement/WJ_2016_02_s57.pdf

Liquation cracking, also known as eutectic cracking, is a type of cracking that can occur in certain types of alloys during the cooling process. This phenomenon happens when one phase of an alloy liquefies before the other phases during cooling, causing localized melting at grain or other boundaries and resulting in thermal strains associated with welding. Liquation cracking is most commonly observed in heat treatable alloys, particularly the 6xxx and 7xxx series aluminum alloys, where low melting point films form at the grain boundaries in the Heat-affected zone (HAZ). It occurs adjacent to the fusion line in a fine equiaxed region of the parent plate, commonly referred to as the white zone (WZ), but can also occur remotely from the weld toe adjacent or perpendicular to the fusion line.

The propagation of liquation cracking happens layer by layer and can lead to the restriction of weld shape, welding speed, and technique. The cracks can also become sites for more serious cracks to occur if not appropriately dealt with. Thus, it is essential to assess the risk of solidification cracking and liquation cracking before starting the welding process, especially in materials like nickel alloys, which are also susceptible to formation of liquation cracks in reheated weld metal regions or parent metal HAZ.

Several factors can increase the susceptibility to liquation cracking, including high thermal gradients, low ductility of the HAZ, and high stress concentrations. Techniques like preheating, post-weld heat treatment, and controlling the welding parameters, such as welding speed and heat input, can reduce the risk of liquation cracking.

In summary, liquation cracking is a type of cracking that occurs during the cooling process of certain types of alloys. It is caused by the liquidation of one phase before the other during cooling and can result in localized melting at grain or other boundaries, combined with the thermal strains associated with welding. Liquation cracking can be prevented or reduced by assessing the risk beforehand and controlling the welding parameters during the welding process.

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Liquation and solidification cracks
Solidification and liquation cracks are two types of cracks that can occur in welded materials. Solidification cracks occur in the weld metal during the solidification process, while liquation cracks occur in the partially melted zone during the solidification of liquated material.

Solidification cracking can occur when the weld metal solidifies and contracts, creating stresses that can result in cracks. Factors that increase the susceptibility to solidification cracks include high thermal expansion, high solidification range, base metal hardness, and high solidification shrinkage.

Liquation cracking, on the other hand, occurs when an alloy containing multiple phases with different melting points is cooled too quickly, resulting in the formation of a liquid-rich region within the solid alloy surrounded by a solid-rich region. Liquation cracking is more likely to occur when the base metal is hard and has a narrow solidification range.

While solidification and liquation cracking are two different types of cracks, they can be related. Observations indicate that liquation cracks in the partially melted zone of wrought base metal have a strong association with solidification cracks in the weld metal, and liquation cracks can act as strong initiation sites for solidification cracks.

http://s3.amazonaws.com/WJ-www.aws.org/supplement/WJ_2015_12_s374.pdf

https://www.researchgate.net/profile/Veli-Kujanp/publication/292839052_SOLIDIFICATION_CRACKING_-_ESTIMATION_OF_THE_SUSCEPTIBILITY_OF_AUSTENITIC_AND_AUSTENITIC-FERRITIC_STAINLESS_STEEL_WELDS/links/5a265203aca2727dd8811a6c/SOLIDIFICATION-CRACKING-ESTIMATION-OF-THE-SUSCEPTIBILITY-OF-AUSTENITIC-AND-AUSTENITIC-FERRITIC-STAINLESS-STEEL-WELDS.pdf