PSI - Issue 28

Giacomo Risitano et al. / Procedia Structural Integrity 28 (2020) 1449–1457 G. Risitano et al./ Structural Integrity Procedia 00 (2019) 000–000

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stress that, if cyclically applied to the material, will increase the microplastic area up to produce microcracks, hence fatigue failure.

Fig. 1. Temperature trend vs. load during a static traction test.

3. Materials and methods 3.1. Experimental setup

Static tensile tests were carried out on 3 specimens made of C45 steel. The specimens have a dog bone shape (Fig. 2a) with a nominal cross section of 12 mm x 6 mm. All the tests were performed with a servo-hydraulic load machine MTS 810 (Fig. 2b) adopting a nominal stress rate equal to 400 MPa/min, able to ensure adiabatic test conditions. An infrared camera FLIR A40 was used, with a sample rate of 2 image per second, to monitor the specimen’s surface temperature. The surface was deeply cleaned from rolling oil by means of absorbent paper; then it was coated with high-emissivity black paint (emissivity up to 0.98).

(b)

(a)

Fig. 2. (a) dog-bone specimen geometry; (b) experimental setup.

The load and temperature data coming from the tests were analysed adopting an algorithm implemented via Matlab® scripts. The specimen rupture instant has been taken as the reference time for synchronizing the data. A