PSI - Issue 16

Eugene Kondryakov et al. / Procedia Structural Integrity 16 (2019) 43–50 Eugene Kondryakov et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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2. Experimental procedure

2.1. Material and specimens

A program of experimental investigations on the influence of shear lips and dimensions of the specimens on the test results was developed. According to this program, a set of the specimens of different types was produced to monitor the direction of their cut out of the metal sheet and direction of the basic notch. The standard specimens (Fig. 1), sub-sized specimens (Fig. 2) and side-grooved specimens (Fig. 3) were produced for the investigations. All the specimens were cut out from sheet steel 45 along the direction of rolled steel. The basic notch was made across the direction of fibers of the rolled sheet to avoid the formation of secondary cracks during impact testing. Thirty specimens of each type were made to be able to plot the curve of ductile-brittle transition and determine the critical brittle temperature.

Fig.1. Standard Charpy specimen.

Fig. 2. Sub-sized specimen.

Fig. 3. Side-grooved specimen.

2.2. Test setup

Impact tests were performed on the instrumented vertical impact testing machine equipped with a multi-channel system of high-speed registration of forces and strains (frequency of discretization is 20MHz), as well as with the system of heating and cooling of the specimens in the temperature range of T= - 150 … +400°С (Kondryakov et al. (2005)). Based on the test results a complete diagram of loading of the specimen in the coordinates 'force-time' P(t) was registered using the strain gauges pasted on the impact tester. The obtained diagrams P(t) with a sufficient resolution