Acknowledgements

4. Result discussion and conclusions

Specimen JIC

164 Contact and Fracture Mechanics

(4 � <sup>2</sup> � 20 mm<sup>3</sup>

kJ/m<sup>2</sup>

(UC = Unloading Compliance; MS = Multiple specimen method)

1 T-CT 598,3 3,0 UC 0.16 T-CT 345,2 7,0 UC CVN 573,1 10,0 MS KLST 513,6 14,0 MS

Table 8. Summarization of average values of fracture toughness results, material AISI 304.

); unloading compliance method of measurement.

Specimen O.16 T-CT KLST (4 � <sup>2</sup> � 20 mm<sup>3</sup>

JIC kJ/m<sup>2</sup> 31,9 2,5 85,7 9,1

Table 9. Comparison of fracture toughness results; material AM Ti6Al4V; geometry, 0.16 T-CT vs. KLST

test preparation, execution and assessment.

point-bend specimens of cross section 2 � 4 mm2

The chapter presented here gives basic overview on issues related to small-size specimen testing in the field of the fracture mechanics tests. Some theoretical background and the relation between values obtained on small- and full-sized specimens for all regimes of the fracture behavior ranging from the lower shelf behavior up to the upper shelf region are shown. Some possibilities on how to resolve the size issue influence of the fracture toughness parameters and the reasons for differences obtained during the evaluation in the first chapter part were presented. An overview of size requirements for a valid value determination of the fracture toughness is also given. The subsequent experimental part is demonstrating results of the fracture toughness determination for three materials covering transition and upper shelf region behavior. As an important part of the fracture toughness tests are tensile properties determination. The chapter is dealing with miniature specimen testing; thus mini tensile tests are presented here for the basic property determination that is necessary for fracture toughness

Avg. St. dev. Avg. St. dev.

Testing in the transition region and evaluation with the use of the Master Curve approach yielded very good result comparability between miniaturized and full-size specimens for the material investigated. Testing program spanning over five specimens' geometries agrees very well with published results and confirms reliable result determination in this region even with the use of the miniaturized specimens including 4-mm-thick mini-CT specimens and three-

crack extension was investigated for stainless steel and Ti-alloy produced by the additive manufacturing process. In the case of the stainless steel, four specimens' geometries were

. The upper shelf behavior with the stable

Number of specimens Specimen

)

This chapter was created with support of the projects TH02020448S service life assessment with the use of miniaturized test specimens, 2017–2020, and Development of West-Bohemian Centre of Materials and Metallurgy No. LO1412, financed by the MEYS of the Czech Rep.
