Influence of different precipitation states of Cu on the quasi-static and cyclic deformation behavior of Cu alloyed steels with different carbon contents

Analysis of the Thermomechanical Fatigue Behavior of Fully Ferritic High Chromium Steel Crofer®22 H with Cyclic Indentation Testing

“…In addition to F max = 1000 mN, a maximum indentation force of 100 mN was used to get a higher resolution of the material volume around the fatigue crack (see Reference [16]). The CITs were evaluated using the PhyBaLCHT procedure presented in detail in References [13,15,16]. During indentation, the indentation force F and indentation depth h are measured continuously, revealing an F-h hysteresis from the 2nd cycle on (see Figure 4b).…”

“…In this context, the results of Reference [13] for precipitation hardened Cu alloyed steels show, that the hardness, as well as the cyclic hardening potential, depend on the number and size, as well as the coherency state of Cu precipitates. Consequently, the Laves phase evolution has to be considered to explain the results observed in CITs.…”

“…The TMF-tests demonstrate, in spite of slightly larger stress range and mean stresses (91 MPa for CroFer ® 22 H and 75 MPa for P91), a higher lifetime for CroFer ® 22 H compared to P91 (see Figure 3). While P91 exhibits a strong degradation of its initial martensitic lath structure, called The CITs were evaluated using the PhyBaL CHT procedure presented in detail in References [13,15,16]. During indentation, the indentation force F and indentation depth h are measured continuously, revealing an F-h hysteresis from the 2nd cycle on (see Figure 4b).…”

“…In general, indentation tests constitute an efficient method to determine various mechanical properties, such as hardness or elastic modulus [11,12]. Furthermore, a material's cyclic properties can be characterized using cyclic indentation tests (CITs) [13][14][15]. As shown by Reference [15] for 100Cr6 and [13] for two copper alloyed steels with carbon contents of 0.005 and 0.21 wt-%, respectively, using CITs enables the determination of the material's cyclic hardening potential, which correlates with the amount of cyclic hardening detected in uniaxial fatigue tests.…”

“…Furthermore, a material's cyclic properties can be characterized using cyclic indentation tests (CITs) [13][14][15]. As shown by Reference [15] for 100Cr6 and [13] for two copper alloyed steels with carbon contents of 0.005 and 0.21 wt-%, respectively, using CITs enables the determination of the material's cyclic hardening potential, which correlates with the amount of cyclic hardening detected in uniaxial fatigue tests. Additionally, preliminary work [16] demonstrates at differently heat-treated 42CrMo4, that the deformation behavior measured in CITs is in good accordance with the cyclic deformation behavior in uniaxial fatigue tests with compressive stresses (R = −∞).…”