Hot Tearing Elimination at DC-casting of Al Alloys
|Coordinator||Mittuniversitetet - Avdelningen för naturvetenskap|
|Funding from Vinnova||SEK 1 795 500|
|Project duration||October 2017 - December 2018|
|Venture||The strategic innovation programme for Metallic material|
Purpose and goal
Hot tearing in AA3003 alloys have been studied in laboratory and in industrial scale in the companies Kubal and Gränges. Aim with the project is to decrease the scrap rate due hot tearing for certain alloys from levels of 25 to 30% down to levels normal for other Al alloys which is about 5%. After the project the scrap rate has been lowered to about 10%. Another aim is to obtain quantitative data for the crack tendency after alloying with certain alloy additions, and such data is now available.
Expected results and effects
An expected and clear result from the experimental work was that decreased cooling rate lowers the crack sensitivity. In industrial trials a new design of the moulds was necessary to achieve a more even and decreased cooling rate, which also improved the casting yield. The most important results from the studies of different alloy compositions was that Cu contents higher than 0.3% increased the crack rate and so did the lowering of the Fe content from the normal 0.2% to 0.14%.
Planned approach and implementation
CRC, i.e. Constrained rod Casting, have been applied to study hot tearing for creation, AA3003, aluminum alloys. Acoustic emission has been applied to obtain more accurate data, however, with no success. SEM has been used to analyze fracture surfaces and for in-situ studies of crack growth. DC simulation equipment has been used to manufacture alloys of compositions not available in the industrial partner companies.