Wpływ kulowania na strukturę, mikrotwardość i naprężenia własne stali austenitycznej 1.4539

Influence of the Thermal Cutting Process on Cracking of Pearlitic Steels

“…Heating to high temperature in the cutting process causes the near‑surface zone to become hardened during the rapid cooling of the material. Compressive stresses occur in the hardened zone due to the phase transitions ( Figure 6 a) [ 19 , 26 , 27 , 28 , 29 ]. Based on the conducted research, it is possible to present the mechanism of steel cracking in the thermal cutting process.…”

“…Based on the research and references [ 26 , 27 , 28 , 29 ], the mechanism of crack formation during the thermal cutting of R260 steel can be presented. The heating of the surface during thermal cutting and subsequent cooling causes phase changes to occur.…”

Problems in assessing the durability of a selected vehicle component based on the accelerated proving ground test

“…The data presented in Table 5 indicate that the calculated spring durability is strongly influenced by the correctly assumed value of compressive pre-stress, which can be identified based on e.g., the as- sessment of the depth of changes in the microstructure of the material, which is the result of shot peening. Such an evaluation may be carried out by, among others, performing material destructive tests of a component [9,13]. The general information provided by the manufacturer about the plastic processing, without detailed data, is insufficient for correct calculation of the component durability.…”

“…With such a procedure, normal compressive stresses, which significantly reduce the values of tensile stresses arising during the component's operation, were introduced on this surface [3,18]. Due to the lack of data on the values of those stresses as well as the depth of their introduction into the material structure, the available data, presented in, e.g., [9,13,15], were used to estimate them. Based on the data, it was assumed that in the unloaded state, compressive stresses might reach the value from 300 to 400 MPa, and the depth of the introduced strains can be 15 -25 μm.…”

Fatigue Life of Austenitic Steel 304 Bolts Strengthened by Surface Treatment with Graphene Oxide Layer and Surface Shot Peening

“…Observation of the fatigue fracture microfractography in the crack initiation areas showed the occurrence of brittle cracks (Figure 11a). As a result of shot peening in the surface layer, the material was strengthened, which caused an increase in the microhardness and compressive residual stresses [15,35]. The highest strengthening and tangential stresses after the shot peening process, according to the Hertz model, occurred below the surface [15].…”