INFLUENCE OF RESIDUAL STRESS LEVEL ON FATIGUE LIFE OF ALUMINUM ALLOY SPECIMEN AND METHODS OF SPECIMEN PREPARATION

1 FIKAR Ladislav
Institution:
1 EXOVA s.r.o., Pilsen, Czech Republic, EU, ladislav.fikar@exova.com
Conference:
24th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, June 3rd - 5th 2015
Proceedings:
Proceedings 24th International Conference on Metallurgy and Materials
Pages:
1227-1232
ISBN:
978-80-87294-58-1
ISSN:
2694-9296
Published:
12th January 2015
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
265 views / 116 downloads
Abstract

Exova Plzeň tests the load control fatigue test according to the required specifications due to the quality control on rolled aluminum sheets and plates.Although the machining process is described in specifications in a very detail way, the first test results were approximately 10 % lower than expected. Some round robin test results met the requirements while some others did not. At first the program was focused on the final step of sample machining, i.e. polishing. Based on consulting other Exova laboratories, West Bohemian University and some producers for turning tool tips, the range of compression residual stress was determined.At the beginning of the program it was incorrectly anticipated that the compression residual stress is caused by polishing; late on was proven that it is caused especially by turning. Next steps were focused on the testing of different types of commercially available tool tips and their geometry. These tests didn’t bring satisfactory results. It led to the first tests of our tool tip modification. In 2011 we started cooperating with the Hofmeister Ltd. Company, who are capable to machine tool tips by laser technology.ČVUT FJFI developed a method of residual stress measurement for our round aluminum samples. At least one sample was machined by each modified tool tip and analysed by ČVUT subsequently.The current results indicate positive progress in reaching the required residual stress level. The repeatability of production and the life time of tool tips are still to be verified.

Keywords: Fatigue, residual stress, tool tip, modification, surface roughness

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