A microscopic study of crack initiation mechanisms in 7075 aluminum alloy sheets

✍ Scribed by D.L. Jones; H. Liebowitz

• Publisher: Elsevier Science
• Year: 1973
• Tongue: English
• Weight: 950 KB
• Volume: 5
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(73)90029-5

✦ Synopsis

Ah&act-A study of the opening mode of crack initiation in 7075-T6 aluminum alloy sheets has been conducted with the aid of a scann@ electron micnxcope. Observations were made from several orientations including the top view of the specimen which showed the notch profile and the edge view of the specimen which showed the entire notch front along the specimen thickness. It was found that the edge view exhibited thefhatsifnsolpsrmMentdcformationatabout55percsntobtbebraaldaOstrroeth.Thesec~stodr theformotdeformstionbnndswhichwere~inthedirectionofthetensilesxisaadapperently&~ limiting regions of homogeneous slip. It is felt that the apptamnce of mkrocrxks at loads approaching the br+@!streagtbwf@ fundamentalimpoWnccintbeformationdthe~fRcturrsurface.ManyoftheK m were i&i&d at intermeu& particles and other met&~@cally weak qions on the notch su&ce. It was also possible to carrelate the strain in the notch with the stress intensity factor for the various loads. Very large plastic strains were observed on the notch tip as compar4 to published values of elongation at-for lmnot&dspecimens.