Stainless steel is the most widely utilized material in various process-based sectors because of its remarkable properties such as resistance to corrosion, better performance and excellent mechanical strength. However, it is prone to acidic corrosive attacks due to various environmental conditions. The paper provides a detailed comparative assessment of corrosion behaviour of stainless steel in various concentrations of acidic environments such as sulphuric acid (H2SO4), nitric acid (HNO3), hydrochloric acid (HCl), etc. The distinctive features of various methods such as cathodic protection, selective alloying, coatings, and surface treatment drawn from the latest published literature are discussed, and suggest that the adaptation of these methods provides the potential to enhance corrosion protection in industrial environment. In nut shell, this review can be used by future researchers for different insights regarding the corrosion mitigation and to facilitate their translation into diverse industry applications.
In the recent past, powder bed fusion-laser beam (PBF-LB) has been used for fabricating high-performance/complex metallic components from primary recycled metallic powders. Previous studies have reported the reuse and recycling of 17-4 precipitate-hardened (PH) stainless steel (SS) primary recycled powder to enhance sustainability and cost efficiency in additive manufacturing (AM) with PBF-LB for a limited number of build cycles. However, little has been reported on the use of secondary recycled 17-4 PH SS mixed powder, possibly due to concerns about chemical inhomogeneity, intermetallic phase formation, and the resulting uncertainty in processability and mechanical performance during PBF-LB fabrication. In this study, the feasibility of using secondary recycled (mixed) powder comprising 17-4 PH SS and Ti-6Al-4 V in the PBF-LB process, with particular emphasis on the potential influence of intermetallic formation in the fabricated components, was evaluated. The study also investigates the effect of scan strategy (SST) (rectangular, strip, and hexagonal) and infill topology (fully solid, Weariphelan (WP), and octet metastructures) on phase constitution, microstructural evolution, melt-pool behavior, solidification characteristics, and mechanical response of parts produced from secondary recycled powder and compares with virgin powder samples. Thermodynamic predictions (pseudo-binary phase diagrams) confirmed the formation of brittle intermetallic phases due to compositional inhomogeneity in the mixed powder, which limits the strain performance of the fabricated components compared to virgin 17-4 PH SS. The results suggest that samples fabricated with WP as the infill pattern (IP) in PBF-LB exhibited the lowest strain ( 7.75
Powder bed fusion-laser beam (PBF-LB) has emerged as a promising route for fabricating complex, patient-specific metallic implants with controlled architectures and tailored mechanical properties. In recent years, significant studies have been reported on the effects of infill patterns (IPs), scan strategies (SSTs), powder recyclability, and process parameters (such as laser power, scanning speed, and energy density) on the microstructure and mechanical performance of PBF-LB-fabricated biocompatible alloys. However, the collective impact of SSTs, IPs, and powder recyclability (which better reflects realistic processing conditions) remains largely unexplored, particularly for biomedical implant applications. In the present work, a Taguchi-based design of experiments (DOE) was employed to systematically investigate the effects of SSTs, IPs, and powder condition (virgin, primary, secondary recycled) on the process stability, microstructural evolution, and mechanical behavior of PBF-LB-fabricated 17-4 precipitate hardened (PH) stainless steel (SS) functional prototypes. Results reveal that among the selected input parameters for PBF-LB, the sample fabricated with virgin (V) powder, rectangular alternate (RA) as SST, and solid (SD) as IP exhibited the highest peak load of 16.04 kN. In comparison, the primary recycled (PR) powder sample, with stripe alternate (SA) as SST and Weaire-Phelan (WP) as IP, exhibited the lowest peak load of 10.04 kN. Overall, the study demonstrates the collective impact of SSTs, IPs, and powder recyclability in tailoring PBF-LB-fabricated 17-4 PH SS functional prototypes for cranio-maxillofacial implant applications.
Electrochemical machining (ECM) is an established toolroom process used for various industrial applications. Numerous studies have been reported on the pulsed and non-pulsed modes of ECM to enhance surface characteristics. Additionally, significant studies have been reported on improving the performance of ECM by partially insulating the cathode with a floating inter-electrode slit (IES) or a fixed thermoplastic cathode cap (TCC), as modified electrochemical machining (MECM). However, little has been reported on the influence of pulsed mode in MECM with TCC to date. This study reports the effect of different sizes of TCC with varying internal cavity area (ICA) and outer cavity area (OCA) while pulsed and non-pulsed modes of MECM with Cu as a tool and Ti alloy as a workpiece (W/P) in terms of material removal rate (MRR) and surface roughness (Ra). In this study, for the pulsed mode, the pulse on time (Ton) and off time (Toff) were set to 100 × 10− 3 s and 25 × 10− 3 s, respectively, at an 8 kHz frequency with an 80
During gas turbine operations, compressor blades play a crucial role in power generation. Here, we address the issue of high pressure, rotational speed, and temperatures which can lead to material deterioration in compressor stator blades. In this study, a comprehensive numerical investigation is conducted to estimate the thermal and structural characteristics of gas turbine compressor stator blades made from AISI 403 martensitic stainless steel and its niobium-enhanced version, AISI 403 + Nb. Finite elements based couples thermo-mechanical simulation is conducted elements in COMSOL Multiphysics to inspect thermal conduction, temperature variations, structural changes, and the generation of stress during the operation of gas turbines. The comparative study reveals that the inclusion of niobium markedly enhances the thermal characteristics of the alloy. The AISI 403 + Nb blade exhibits a more consistent temperature distribution and diminished thermal gradients, resulting in decreased thermal stresses and enhanced structural integrity. Furthermore, the overall deformation is less than that of standard AISI 403, indicating improved durability against thermo-mechanical loading. These findings affirm that AISI 403 + Nb is a promising material for long-lasting and sustainable applications in compressor stator blades.
