Fundamentos teóricos da mecânica da fratura e o método de Herrera e Landes para determinar a curva J-R.

Abstract

In this work the foundations of fracture mechanics theory, its equations and fundamental relationships as well as the method of single specimen test to determine the J-R curve were studied. Herrera and Landes normalization method(Key Curve) to determine the J-R curve was studied. Its aplicability was analised for two HSLA steels: a controlled rolled API 5L-X70 pipelines steel plate, produced with inclusions morphology control, and an ASTM A516-GR65 pressure vessels steel plate. The tests were made at room and low temperatures and three point bend specimens were used. The normalization curve(Key Curve) was analytically determined and the points fit was executed by a power lay. The Ramberg Osgood's functional form relationship was used. It was observed that material fracture toughness affects the power law exponent. The results were confronted with other obtained by the multiple specimens test method. Such procedure brought in to evidence that Herrera and Landes normalization method is suitable to determinate J-R curve for the studied steels.