Shiraz University Iranian Journal of Materials Forming 2383-0042 13 3 2026 07 01 Enhanced Densification and Mechanical Performance of Fused Silica via Gel Casting 4 11 8571 10.22099/ijmf.2026.54471.1356 EN Mozhgan Afgarazordeh Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz, Iran Mohammad Hossein Paydar Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz, Iran Journal Article 2025 10 07 The sintering behavior, phase evolution, and mechanical properties of fused silica ceramics were systematically investigated for samples fabricated by gel casting and dry pressing. Gel-cast samples were prepared using an optimized aqueous formulation containing 58 wt.% solids, whereas dry-pressed compacts were produced at 100 MPa. All specimens were sintered in air between 1100 °C and 1300 °C for 5 h. Dilatometric analysis revealed distinct densification characteristics for the two forming methods. Despite their lower initial green density (~30–33% of theoretical), gel-cast bodies exhibited faster and more complete shrinkage than dry-pressed samples (~57–60% of theoretical), achieving near-full densification above 1150 °C. This enhanced sintering efficiency is attributed to the superior microstructural homogeneity of gel-cast green bodies, whose fine and interconnected pore network provides higher capillary driving forces and more efficient mass transport during viscous sintering. In contrast, heterogeneous particle packing in dry-pressed compacts produced isolated pores that impeded densification. Flexural strength increased with sintering temperature but decreased with higher polymer content due to residual porosity formed during burnout. The maximum strength (~85 MPa) was observed for gel-cast specimens sintered at 1250 °C, while a subsequent drop in 1300 °C corresponded to extensive cristobalite crystallization, as confirmed by XRD and SEM. Crystallization induced microcracking and limited further densification. These results demonstrate that microstructural uniformity is more critical than initial green density for achieving dense, high-strength fused silica. Gel casting thus represents a superior forming technique for producing defect-free amorphous silica ceramics below the cristobalite formation threshold.

https://ijmf.shirazu.ac.ir/article_8571_03f597209ebc1a8db892ea6e770e7cba.pdf

Shiraz University Iranian Journal of Materials Forming 2383-0042 13 3 2026 07 01 Investigation of Globularization and Mechanical Behavior of Ti-8Al-1Mo-1V Alloy During Post-Deformation and Heat Treatment 12 25 8594 10.22099/ijmf.2026.54721.1360 EN Gholamreza Ebrahimi Department of Materials Science and Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran Zahra Mirzaie Department of Materials and Polymers Engineering, Faculty of Engineering, Hakim Sabzevari University, Sabzevar, Iran Hamidreza Ezatpour Department of Materials Engineering, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran Journal Article 2025 11 01 In this study, the effect of hot compression and subsequent heat treatment on α globularization and mechanical properties of Ti-8Al-1Mo-1V (Ti-811) alloy with an initial lamellar microstructure was investigated. Heat treatment was performed on hot-deformed samples (at 1000 °C and 0.001 s-1), at temperatures of 800, 850, and 900 °C for durations ranging from 1 h to 5 h. The results showed that the microstructural changes depended on the temperature and time of heat treatment and globular α phase fraction increased with increasing time and temperature. By increasing the heat treatment temperature from 800 °C to 900 °C for 5 h, the volume fraction of globular α phase increased from 68% to 79% and the aspect ratio decreased from 7.2 to 6.2. Microstructural studies showed that the globularization mechanism was controlled by boundary splitting, interface migration, and Ostwald growth. At lower temperatures of 800 °C and 850 °C, the dominant mechanism was boundary splitting by the shearing of α layers, which depended on the amount of pre-strain. At the higher temperature of 900 °C, globularization was controlled by interface migration and Ostwald growth, which were diffusion processes and dependent on heat treatment time. The static globurization kinetics of Ti-811 during heat treatment was well modeled by the modified JMRE equation, with a correlation coefficient (R) of 0.97 and the mean absolute relative error (MARE) of 7.19%. A punching test was applied to evaluate the mechanical properties of the deformed and heat-treated samples. The maximum shear strength and elongation were obtained at 900 °C and a holding time of 2 h, which were equal to 695 MPa and 1.1, respectively.

https://ijmf.shirazu.ac.ir/article_8594_a238308719ec41e476bcfb4dca7db11f.pdf

Shiraz University Iranian Journal of Materials Forming 2383-0042 13 3 2026 07 01 An Alternative Model for Investigating the Kinetics of Deformation-Induced Martensitic Transformation 26 33 8603 10.22099/ijmf.2025.55110.1365 EN Kimia Saberi Tavakoli School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran Hamed Mirzadeh School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran Journal Article 2025 12 05 Many austenitic stainless steels have a metastable austenite phase that transforms into α'-martensite during deformation at room and cryogenic temperatures. Given the significance of the deformation-induced martensitic transformation for strengthening, plasticity, and grain refinement, examining the kinetics of this transformation is an important issue. Accordingly, in the present work, an alternative kinetics model was introduced and verified by considering strain, deformation temperature, chemical composition, and strain rate as the main variables. This model was formulated as fα' / fsat = 1/{1+1/(λε)m}, where fα' and fsat represent the volume fraction of α΄-martensite and its saturation value, respectively; ε is the equivalent strain, m was obtained as approximately 3 for the effect of deformation temperature and strain rate on α'-martensite formation in AISI 304 and AISI 301LN stainless steels, and λ was found to be a reliable metastability parameter. In the proposed model, λ and m can be determined without the need for non-linear regression, which is a clear advantage compared to other models. The proposed model was benchmarked against the well-known Olson-Cohen model, highlighting its advantages and confirming that it can serve as a viable option for future research works on austenitic stainless steels, advanced high-strength steels, and high-entropy alloys.

https://ijmf.shirazu.ac.ir/article_8603_7123dba2ac980cd655924910ba4d0c01.pdf

Shiraz University Iranian Journal of Materials Forming 2383-0042 13 3 2026 07 01 Development of the Maximum Rate of Dissipation Criterion to Analyze the Deformation Mechanisms in Semi-Solid State 34 51 8647 10.22099/ijmf.2026.55062.1361 EN Mohammad Hadi Sheikh Ansari Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran 19991-43344, Iran Mehrdad Aghaie Khafri Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran 19991-43344, Iran Journal Article 2025 11 30 This study presents a new perspective on semi-solid rheology by applying the maximum dissipation rate criterion and stability analysis. Using this approach, we developed a criterion that identifies the conditions under which different deformation mechanisms dominate. A key finding is the critical role of rate-sensitivity in shaping both the mode and intensity of deformation. Specifically, we identify a threshold rate-sensitivity value of m = 0.21. Below this threshold, deformation is governed by granular processes such as grain rearrangement, jamming, and dilatancy. Above it, conversely, solid grains undergo plastic deformation instead. The analysis also establishes a strong correlation between dilatancy and rate-sensitivity. In the granular regime, higher rate dependency, resulting from increased solid fraction and stronger grain interconnections, promotes greater dilatancy and increased tendency for shear localization. At the critical threshold, localization emerges as bonds between grain agglomerates break, triggering Reynold’s dilatancy. Collectively, these findings highlight that semi-solid materials exhibit granular-like behavior, wherein grain and agglomerate rearrangement, coupled with dilatancy, drive the transition toward shear banding following the failure of inter-particle bonds. These insights provide a clearer framework for understanding and predicting the complex behavior of semi-solid materials under load.

https://ijmf.shirazu.ac.ir/article_8647_64a57550f81fbaeb357b3282910566d6.pdf

Shiraz University Iranian Journal of Materials Forming 2383-0042 13 3 2026 07 01 Experimental Study of Sheet Incremental Forming Process with Controlled Movement of Material into the Forming Cavity 52 63 8667 10.22099/ijmf.2026.55101.1364 EN Seyed Jalal Hemmati Department of Mechanical Engineering, University of Hormozgan, Bandar Abbas, Iran Mohammadreza Kamranfard Department of Mechanical Engineering, University of Hormozgan, Bandar Abbas, Iran Mohsen Moridi Department of Mechanical Engineering, University of Hormozgan, Bandar Abbas, Iran Journal Article 2025 12 04 Incremental forming is one of the methods for single-piece forming of metal sheets. In the conventional configuration of this process, the sheet is held fixed between holders, preventing any movement toward the forming cavity. Since the presence of draw beads in deep drawing dies controls the material flow into the die, thereby reducing defects such as wrinkling and thinning, this study incorporates this feature into the design of the holders in sheet incremental forming. Experimental tests were conducted both with and without the bead, and the effect of its presence on sheet thickness variation and forming accuracy was evaluated. In this context, with a different definition of the bead performance, its positive role in the incremental forming process is also noticeable, with the distinction that the blank holder’s role is to control the contact surface between the sheet and the holders and to regulate friction. Experimental observations confirm that in the case of linear contact between the holders and the workpiece through a double bead, controlled movement of the sheet into the cavity is possible, which in turn reduces thinning by approximately 30% while maintaining forming accuracy.

https://ijmf.shirazu.ac.ir/article_8667_c92c2f18015a4e83e9f747474c4cf6f2.pdf

Shiraz University Iranian Journal of Materials Forming 2383-0042 13 3 2026 07 01 Numerical and Experimental Investigation of Deep Drawing Process of Square Cross-Section Cups Made of St37 Without Blank Holder 64 76 8679 10.22099/ijmf.2026.54118.1347 EN Saeid Kashi Department of Mechanical Engineering, Tafresh University, P.O. Box: 79611-39518, Tafresh, Iran Siamak Mazdak Department of Mechanical Engineering, Faculty of Engineering, Arak University, Arak 38156-88349, Iran Mohammad Reza Sheykholeslami Department of Mechanical Engineering, Faculty of Engineering, Arak University, Arak 38156-88349, Iran Mahsa Shahsanami Department of Mechanical Engineering, Faculty of Engineering, Arak University, Arak 38156-88349, Iran Vahid Fartashvand Department of Industrial Design, Faculty of Art, Alzahra University, Tehran, Iran Journal Article 2025 09 05 Conical dies without blank holders are an interesting subject for metal-forming applications because of their structural simplicity and reduced tooling complexity. However, reduced control of material flow and the increase likelihood of defects, such as excessive thinning and shrinkage, are the main limitations of this process. Therefore, proposing an optimum angle to mitigate this limitation is essential. In this study, the effects of the die half-cone angle and drawing ratio on the thickness distribution and equivalent plastic strain during the deep drawing of a square cup were investigated numerically and experimentally. A statistical study using a full factorial design was employed to examine various combinations of die half -cone angles and drawing ratios. Using this method, the combined effect of the die angle and yield drawing ratio on the thickness distribution and plastic strain was investigated. Despite previous studies suggesting a die with an 18° angle, the results showed that reducing the angle to 16° led to a more uniform thickness distribution and a lower maximum equivalent plastic strain. Specifically, at a drawing ratio of 1.87, the use of a 16° die angle resulted in a 28% reduction in thinning and a 14% reduction in thickening compared with the 18° die angle.

https://ijmf.shirazu.ac.ir/article_8679_5a1ef8f473baae2c53e113ebb894b52b.pdf