Two-stage microplastic surface deformation in Al 2219-T851

Cox, Brian N.; Morris, W. L.; James, Michael R.

doi:10.1016/0001-6160(87)90010-1

Cited by 6 publications

(1 citation statement)

References 5 publications

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“…All of the activities up to date centered or the literature survey and evaluation of the microstructure based crack growth and life prediction models proposed during past few years. There are several models of his type in the literature but most of them take only-grain size and shape [4][5][6][7][8][9][10] or texture [ 11,17,19] into account and they usually describe behavior of small fatigue cracks [12][13][14][15][16]. We are interested in the models which take all above factors into account and which would also consider influence of the second phase particles and/or voids and orientations of grain boundaries with respect to the moving crack.…”

Section: Modelingmentioning

confidence: 99%

Development of the Microstructure Based Stochastic Life Prediction Models

Przystupa¹,

Zhang²,

Luévano³

1991

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The purpose of the fatigue life prediction program at UCLA is to characterize the accumulation of the microstructural damage during fatigue of the aluminum alloys and to use obtained data in the formulation of the microstructure based stochastic life prediction models. Emphasis during the first year of the program was on the implementation of all required quantitative microscopy techniques and on the characterization of the starting microstructures in the "high" and "low" porosity 7050-T7451 commercial plate alloys.The first assembled set of data includes characteristics of the grain structures, constituent particles and pores on the sections parallel to the plate surface as a function of the distance from the surface. The results show that both alloys have partially recrystallized structure with the recrystallization levels changing from zero at the surface to about 200/ in the center. The unrecrystallized grains are 85 to 240 pm in size, while for the recrystallized ones the sizes are in the 45 to 85 pm range. The average pore size is 7.74 PM for the high porosity alloy and 7.15 pm for the low porosity material with the area fractions of 0.074% and 0.072% respectively. The sizes of the constituent particles are 8.38 and 8.21 Pm and the area fractions 0.88/ and 0.65% for the high and low porosity alloys respectively. Preliminary results from the tessellation analysis indicate that the pores have spatial distribution which can be categorized as regular with clusters. For the constituent particles the distributions are clustered. A number of the constituent particles have cracks and the measurements of their frequency are in progress. The most common precipitate phases present in the alloy are il', 111, 11 2 and 14. The precipitates inside the grains are small ranging from 5 to 45 nm in diameters while precipitates on the grain boundaries are generally larger and their sizes vary between 20 -250 nm. Precipitate free zones have been also observed and the measurements of their characteristics are in progress. The theoretical efforts during the first year of the program have been limited to the literature survey of the available stochastic life prediction models and to the development of a preliminary Markov chain model. Plans for the 1992 include finishing "' characterization of the 7050 alloys, formulation of the preliminary life : L prediction models and start of the characterizations of the 8090 alloys.

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