PSI - Issue 41

Hryhoriy Nykyforchyn et al. / Procedia Structural Integrity 41 (2022) 326–332 Hryhoriy Nykyforchyn, Vitaliy Pustovyi, Olha Zvirko et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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Table 2. Impact toughness and the stress range for the tested units of the portal crane Sokol No. Crane unit  σ e [MPa] KCV e [J/cm 2 ] 1 Jib, lower shelf 130 60 2 110 95 3 Boom, back shelf 48 114 4 55 123 5 Movable counterweight, upper shelf 45 127 6 50 177 7 Right column wall 120 45 8 145 53 9 Back column wall 70 125 10 100 137

A relationship between the obtained values of stress range Δσ e and impact toughness KCV has been established: the higher the stress level, the lower the resistance to brittle fracture. Indeed, the highest Δσ e = 145 MPa corresponds to the lowest KCV = 53 J/cm 2 , whereas the highest KCV = 177 J/cm 2 is obtained for one of the least stressed units with Δσ e = 50 MPa. This means that it is the level of in-service cyclic stresses that determines the degree of operational degradation of the metal. In addition, Nemchuk and Krechkovska (2019) and Krechkovska (2022) emphasized that for rolled steels, microdelaminations along the rolling direction are also highly contribute to the drop in the operational loss in impact toughness. On the other hand, a conclusion can be drawn about uneven stress distribution over the installation leads to faster deterioration of more stressed units. 4. Role of corrosive environment in operational loss of serviceability of hoisting and transporting equipment One of the consequences of the operational degradation of port metal structures is the intensification of corrosion processes. Pustovoi et al. (2015), Nemchuk and Zvirko (2020), Lesiuk et al. (2020) and Zvirko (2022) showed that the long-term operated steel corrodes faster than the as-received or normalised one. This means that the current technical state of a metal under operation should be also taken into account when predicting corrosion losses and metal thinning. It, in turn, depends on the level of operational stresses. In other words, a higher stress level leads to more intensive degradation of the metal that in turn causes corrosion acceleration.

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Fig. 2. Relationship between the resistance to brittle fracture KCV and corrosion resistance R p for the steel taken from various units of the operated crane Sokol.