In the present work, a study of the separability property, experimental ηpl factor determination, and load normalization AA 6061-T6 aluminum alloy is described. The separability property has been studied using the Sij parameter with Standard ASTM E 1820-96 SE(B) blunt notch specimens with 8 and 24% side grooving.
The deformation property function H, from variable separability property, was written in terms of plastic and total displacement. The ηpl factor was determined using the Sharobeam and Landes methodology with two side grooves and the two H functions. The ηpl factor values obtained with the H function evaluated in terms of the total and plastic displacement differed by less than 1.4%. The values obtained were close to that suggested in ASTM E 1820-96.
In order to estimate crack length from the test record, the unloading and normalization load methodologies were used. Special attention was paid to the point where the domain of definition of the separability property in plastic displacement started and the influence it had on the estimated crack length. The normalization load was described by means of a standard and a modified power law, and calibration curves were obtained for blunt notched and fatigue precracked specimens.
The degree of restraint introduced by different side-grooving ratios had an influence on the resulting J-R curve, and the three methods employed were sensitive to this change. The toughness obtained with the geometry, dimensions, constraints, test conditions, and material used in this work with different estimation methodologies were in relatively good agreement.
This paper reports the results obtained in a research conducted to evaluate austempered ductile iron (ADI) as a wear resistant material for the production of machine parts processed at intermediate and high austempering temperatures (Ta). Severe abrasion in actual service performance trials and low stress abrasion laboratory tests (ASTM G-65) were carried out along with microstructural characterization by optical microscopy and X-ray diffraction. The results derived show that ADI yields excellent abrasion resistance under the operating conditions resulting from the field tests when Ta is raised. Nevertheless, ADI show an opposite trend under the low stress abrasion conditions imposed by the dry sand/rubber wheel abrasion apparatus (ASTM G-65). The presence of a metastable and ductile ausferrite phase (reacted and unreacted austeniteϩferrite) in ADI microstructure appears to be the most relevant factor influencing the performance observed. In addition to a high deformation capability detected at the wear surfaces, an austenite to martensite transformation took place as determined by X-ray diffraction. These two factors combined make the ausferritic microstructure overcome hardness reduction when the austempering temperature is raised, improving or sustaining the resistance to severe abrasive wear but, at the same time, increasing impact toughness.
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