Masing Behavior and Microstructural Change of Quenched and Tempered High-Strength Steel Under Low Cycle Fatigue

Abstract

Low cycle fatigue behavior of a quenched and tempered high-strength steel (Q960E) was studied in the strain amplitude ranging from ± 0.5% to ± 1.2% at room temperature. As a result of fatigue loading, the dislocation structural evolution and fracture mechanism were examined and studied by transmission electron microscopy and scanning electron microscopy (SEM). The results showed that this Q960E steel showed cyclic softening at different strain amplitudes, and the softening tendency was more apparent at strain amplitude of ± (0.6-1.2)% than that at ± 0.5%. The reduction in dislocation density with increasing strain amplitude is responsible for the softening tendency of cyclic stress with the strain amplitude. The material illustrates near-Masing behavior at strain amplitude ranging from ± 0.6% to ± 1.2%. The near-Masing behavior of Q960E high-strength steel can be the result of stability of martensite lath at different strain amplitudes. Partial transformation from martensite laths to dislocation cells is responsible for the derivation from ideal Masing behavior. In the SEM examination of fracture surfaces, transgranular cracks initiate on the sample surface. Striations can be found during the crack propagation stage.

A comprehensive review and analysis of Masing/non‐Masing behavior of materials under fatigue

“…This method can be used to predict W f for any strain amplitude provided the material constants S 1 and S 2 are determined from a sufficient number of LCF tests. The authors 11,12 have validated the applicability of Equation 5 12 with 13 different materials (304L SS, 12 304LN SS, 16 316LN SS, 91 SA333 Gr.6, 16 AA6063, 79 AISI 1018 HR steel, 7 annealed Cu, 119 annealed Al, 119 BLY160 steel, 14 AISI 321 SS, 13 LY225 steel, 25 HSS Q960E, 88 and AL6XN steel 120 ) that include Masing, non-Masing (Type-I) and non-Masing (Type-II) behaviors. 11,12…”

“…The influence of strain amplitude on the Masing/non‐Masing behavior has been investigated for different classes of materials in the literature 88–90 . In 316LN SS, Roy et al 91 observed Masing behavior at lower strain amplitudes (<±0.5%) and non‐Masing behavior at higher strain amplitudes (>±0.5%).…”

“…The influence of strain amplitude on the Masing/non-Masing behavior has been investigated for different classes of materials in the literature. [88][89][90] In 316LN SS, Roy et al 91 observed Masing behavior at lower strain amplitudes (<±0.5%) and non-Masing behavior at higher strain amplitudes (>±0.5%). Further investigations by Goyal et al 23 on the 316LN SS revealed the presence of planer slip with dislocation pile-up at a lower strain amplitude (±0.4%), and at high strain amplitude (±0.8%), the tendency towards cell structure formation had been observed by TEM.…”

“…The CPSED (Figure 19A) and fatigue life prediction (Figure 19B) could be made within a scatter band of 1.2 and 2, respectively. 11,12 The 13 different materials are 304L SS, 12 304LN SS, 16 316LN SS, 91 SA333 Gr.6, 16 AA6063, 79 AISI 1018 HR steel, 7 annealed Cu, 119 annealed Al, 119 BLY160 steel, 14 AISI 321 SS, 13 LY225 steel, 25 HSS Q960E, 88 and AL6XN steel. 120 The proposed method (Equation 12) is claimed to be universal in nature as it could be used for all those 13 materials, among which some were showing Masing behavior, and others were showing non-Masing (Type-I) and non-Masing (Type-II) behavior.…”

Low-cycle fatigue mashing behaviours of HTRB630 high-strength steel exposed to high temperatures

“…The plastic strain energy density is an important index for evaluating the fatigue damage of mechanical materials [23]. The calculation method for the plastic strain energy density differs depending on whether the material exhibits mashing behaviour [24,25], which refers to the half-life [26] hysteresis curves of different strain amplitudes, moving the lowest point of each hysteresis curve to a certain point. If the upper half of the hysteresis curve overlaps, the material exhibits mashing behaviour [26].…”