PSI - Issue 81

Viktor Kovalov et al. / Procedia Structural Integrity 81 (2026) 346–352

349

After PMFT, improved structural uniformity was observed, accompanied by a reduction in the number of crack-initiating defects and a more stable fracture morphology. The cracked surface layer of the original and PMFT-treated samples is compared in Fig. 2. PMFT-treated samples exhibit a thinner cracked surface layer and reduced intensity of secondary cracking, confirming the positive effect of magnetic processing on crack propagation resistance and structural stability.

Fig. 2. Cracked surface layer of the original sample and the sample after PMFT

More detailed fractographic features of fracture in carbide inserts obtained after laboratory and operational tests are presented in Fig. 3. These images illustrate the transition from dominant main-crack-controlled fracture in highly defective material to a more distributed system of parallel and branched cracks in PMFT-treated material. This behaviour indicates increased resistance to brittle fracture and enhanced energy dissipation during crack growth.

Fig. 3. Fractographic features of fracture in carbide inserts (optical and SEM microscopy)

3.3. Statistical Evaluation of Strength and Reliability Statistical evaluation was performed to quantify the variability of mechanical and operational characteristics of the carbide inserts and to assess the reliability of the material as a function of defect distribution. The analysis included determination of the coefficient of variation, mean tool life, and γ - percent tool life (γ = 80%). The coefficient of variation was used as a quantitative indicator of the stability of mechanical properties and tool life. A pronounced reduction in the coefficient of variation after PMFT indicates a more uniform structural state and a decrease in defect driven scatter of strength and durability parameters. The mean tool life and γ -percent operational life were determined from statistical processing of tool wear and failure data. While the mean life reflects the average performance of the tool, the γ -percent life is more sensitive to early failures and therefore provides a more conservative and practically relevant reliability metric for heavy-duty machining. The experiments demonstrated