Small Molten Research Articles

Integrating Small Modular Reactors and Policy Frameworks for Sustainable Energy Security in Indonesia

This study evaluates the potential of Small Modular Reactors (SMRs) as a sustainable solution for Indonesia's energy diversification. Amid Indonesia’s rising energy demands and environmental commitments, SMRs-particularly Small Modular Molten Salt Reactors (SM-MSRs)-present an alternative to conventional power sources. SMRs offer advantages like modularity, operational efficiency, and safety, making them suitable for Indonesia’s geographically dispersed landscape. Using a qualitative descriptive approach, this research examines the technical, regulatory, and societal factors influencing SMR integration. Findings reveal that while SMRs show competitive Levelized Cost of Electricity (LCOE) compared to coal, challenges remain, including stringent regulatory requirements, high initial capital costs, and limited public acceptance due to nuclear safety concerns. Policy adjustments, community engagement, and collaboration with established SMR programs globally are suggested to address these issues. Additionally, SMRs’ scalability and compatibility with renewables support Indonesia’s goals for a resilient energy mix, potentially transforming remote energy access. This comprehensive approach underscores the viability of SMRs within Indonesia’s energy transition, contributing to a cleaner, more flexible energy infrastructure

Investigation of Co-Cr alloy layer prepared by laser metal deposition

Abstract Additive technologies are commonly used for component production and repair. Laser metal deposition is a type of additive technology that can create new bodies or add new components to existing parts. This technology enables continuous modification of the chemical and material properties of the deposited layer to suit the intended purpose. The alloying powder is dissolved and mixed in a small volume molten pool during laser deposition. The laser cladding process is known for its rapid heating and cooling rates. This can result in partial or non-existent dissolution of powder particles in the molten pool, or the formation of non-equilibrium microstructures that cannot be achieved through conventional metallurgical processes. As a result, this method can be used to create materials with unique combinations of properties. In this study, a Co-Cr coating layer was applied to a structural steel base plate. The parameters combination was generated using Taguchi’s experimental design. The relationship between the parameters and the properties of the prepared coating was evaluated using the Taguchi method.

Core neutronic design of small modular molten salt reactor for submarine propulsion

Molten salt reactor (MSR) shows great promise as a Generation IV nuclear reactor concept with high thermal-electric conversion efficiency, inherent safety features, and online reprocessing capability. During operation, the molten salt reactor MSR does not require a long refueling shutdown owing to online fuel reprocessing, making it suitable for watercraft propulsion. This paper presents the neutronic design of the 250 MWt iso-breeder MSR concept for submarine propulsion. The reactor is fueled with LiF-BeF2-ThF4-233UF4 salt with a virtual one-and-a-half fluid configuration. The MSR core is moderated with beryllium oxide and equipped with a high-density graphite reflector to improve neutronic. All calculations on the reactor core design were performed using MCNP6.2 code with ENDF/B-VII.0 neutron cross-section library. As a part of the neutronic analysis, the calculated parameters were the effective multiplication factor (), temperature coefficient of reactivity (TCR), and breeding ratio (BR). The value of ± 1.005 was obtained using Th : U ratio of 98.42% : 1.58%. The TCR value was obtained at -2.56 pcm/K, while the BR value was 1.057. These initial values indicate that the marine propulsion MSR can achieve iso-breeding with inherent safety characteristics. By using MSR design, it is hoped that the submarines will be able to reach significantly longer operational range than its Diesel-powered counterpart..

Core Optimization for Extending the Graphite Irradiation Lifespan in a Small Modular Thorium-Based Molten Salt Reactor

The lifespan of core graphite under neutron irradiation in a commercial molten salt reactor (MSR) has an important influence on its economy. Flattening the fast neutron flux (≥0.05 MeV) distribution in the core is the main method to extend the graphite irradiation lifespan. In this paper, the effects of the key parameters of MSRs on fast neutron flux distribution, including volume fraction (VF) of fuel salt, pitch of hexagonal fuel assembly, core zoning, and layout of control rod assemblies, were studied. The fast neutron flux distribution in a regular hexagon fuel assembly was first analyzed by varying VF and pitch. It was demonstrated that changing VF is more effective in reducing the fast neutron flux in both global and local graphite blocks. Flattening the fast neutron flux distribution of a commercial MSR core was then carried out by zoning the core into two regions under different VFs. Considering both the fast neutron flux distribution and burnup depth, an optimized core was obtained. The fast neutron flux distribution of the optimized core was further flattened by the rational arrangement of control rod channels. The calculation results show that the final optimized core could reduce the maximum fast neutron flux of the graphite blocks by about 30% and result in a more negative temperature reactivity coefficient, while slightly decreasing the burnup and maintaining a fully acceptable core temperature distribution.

Multi-objective capacity configuration optimization of a nuclear-renewable hybrid system

Integrating the energy storage and the base-load energy can be an efficient solution to cover the fluctuation of renewable energy. A nuclear-renewable hybrid energy system consisting of a small modular thorium molten salt reactor, solar photovoltaics, wind turbines, thermal energy storage and battery storage with two operation modes is proposed to meet the community load demand. The methodology combining multi-objective evolutionary algorithms with multi-criteria decision-making method is used to identify the optimal operation mode and gain the optimal configuration of the proposed nuclear-renewable hybrid energy system. In the first stage, the multi-objective evolutionary algorithm with better performance is utilized to gain Pareto solutions to minimize the levelized cost of energy while ensuring an acceptable level of deficiency of power supply probability. In the second stage, the multi-criteria decision-making method is adopted to select the best solution from the obtained Pareto frontiers. The optimization results demonstrate that the nondominated sorting genetic algorithm has the best performance compared with other algorithms and the operation mode with battery discharged first is more cost competitive. It is concluded from the results analysis that the selection of optimal mode is influenced by seasonal variation that contributes to large energy storage capacity requirement.

Study on the cantilever ratio optimization of high-temperature molten salt pump for molten salt reactor based on structural integrity

The high-temperature molten salt pump is the core equipment in the small modular molten salt reactor with media temperatures up to 700 °C. The cantilever ratio of the molten salt pump is usually large. Excessively large cantilever ratios cause increased deformations and rotational amplitudes at the impeller, thus affecting the operational stability of the main pump; small cantilever ratios cause heavy temperature gradients, thus affecting the structural integrity evaluation. This paper used numerical simulation methods to calculate and analyze the temperature field, stress, and structural integrity, optimized the pump shaft cantilever length of the original scheme based on structural integrity using the dichotomy method, and analyzed the rotor dynamics of the optimization results. The results of this study show that the thermal expansion load caused by the temperature difference has a significant mechanical effect on the structure; the first-order critical speed of the rotor system of the optimized schemes has been improved, and the amplitude of the unbalanced response has been significantly reduced, which not only improves the operational stability of the rotor, also contributes to the compact design of the main pump of a small modular molten salt reactor.

Development of Two-Step Method for Fast Chloride MSR Neutronics

This work presents neutronics models of a small and large fast-spectrum molten chloride-salt reactor. The models are similar to designs being pursued by industry, and they may serve as generic preconceptual and simplified neutronics models that provide information for decision making in licensing-related areas. The two models were created using Serpent, a Monte Carlo neutron transport code, and Moltres, a neutron diffusion core simulator tool. Specifically, this study focused on exploring the applicability of diffusion theory to fast molten salt reactor (MSR) models, the capabilities of an open-source, MSR-oriented simulation tool (Moltres), and optimal energy-group structures. The proposed two-step method involves group-constant generation with Serpent and a multigroup diffusion solution by Moltres. Three energy-group structures were applied. The accuracy of the solutions was determined through comparisons between the two-step and Monte Carlo flux and multiplication factor solutions. The findings indicated diffusion theory captures neutronics with minimal error for the large MSR and yielded best results with the 27-group structure. The 27-group structure yielded an average group flux error below 2% and keff agreement between diffusion and transport solutions within 30 pcm. The accuracy of the two-step method decreased for the very small (high-leakage) fast chloride MSR, but the neutronics were captured acceptably well with the 33-group structure. In addition to exploring the capabilities of Moltres, this work contributes to the sparse literature involving open-source models of fast-spectrum MSRs. Future work is noted as expanding the capabilities of the neutronics models to incorporate thermal hydraulics.

Solidification behavior and continuous preparation process of high-quality Zr-based metallic glass plates based on twin-roll strip casting

Metallic glasses exhibit excellent comprehensive properties in a variety of disciplines including mechanics, magnetism, electricity, and chemistry, making them highly promising for various applications. However, the current lack of continuous and efficient preparation technology for metallic glasses not only hinders the research and application of various metallic glass products but also contributes to the high cost associated with their production. In this study, we incorporate the twin-roll strip casting technology into the continuous fabrication process of metallic glass plates. By conducting numerical simulations and practical experiments, we elucidated the solidification process of metallic glasses in the twin-roll strip casting process. A process control strategy was developed focusing on "small molten pool height and low exit temperature", which enabled successful preparation of high-quality Zr55Cu30Al10Ni5 metallic glass plates ranging from 0.13 to 0.56 mm in thickness. A reduced pool height can enhance the cooling rate of metallic glasses and suppress the formation of vortices and crystals within the molten pool. By employing a lower exit temperature, it is possible to achieve a metallic glass plate characterized by high-energy microstructure, exceptional mechanical properties, as well as superior shape and surface quality. This research provides valuable guidance for continuous production of superior-grade metallic glass plates using twin-roll strip casting technique.

Hydrogen Bonds in Perovskite for Efficient and Stable Photovoltaic†

Comprehensive SummaryOwing to their distinctive optical and physical properties, organic‐inorganic hybrid perovskite materials have gained significant attention in the field of electronic devices, especially solar cells. The achievement of high‐performance solar cells hinges upon the utilization of top‐notch perovskite thin films. Nevertheless, the fabrication process involving solutions and the polycrystalline nature of perovskite result in the emergence of numerous defects within the perovskite films, consequently exerting a deleterious influence on the overall performance and stability of the devices. Improving the performance and stability of perovskite solar cells by additive engineering to suppress/passivate defects is a viable approach, which involves hydrogen bond interactions in these device engineering processes. This review explores the intrinsic hydrogen bonds in methylammonium and formamidium lead triiodide, while also considering cation rotations, phase transitions, and stability. Moreover, the review classifies additives into distinct categories, including organic small molecules, polymers, nanodots, classical salts, ionic liquids, and molten salts. The various forms and characterization techniques of hydrogen bonds are discussed, as well as their potential synergistic effects in conjunction with other chemical interactions. Furthermore, this review offers insights into the potential utilization of hydrogen bonds to further enhance the performance and stability of devices. Key ScientistsIn 2009, Tsutomu Miyasaka et al. prepared the first perovskite solar cell, which kicked off the research on perovskite light‐absorbing materials. However, the use of liquid electrolytes led to device instability. The transition to all‐solid‐state perovskite solar cells was realized by Nam‐Gyu Park's team in 2012, which was the beginning of high‐efficiency perovskite solar cells. Subsequently, a number of scientists have innovated the preparation ground process. Methods such as two‐step deposition by Michael Grätzel in 2013 and anti‐solvent extraction by Sang II Seok's team in 2014 were instrumental in advancing the development of perovskite. Liyuan Han's team then increased the cell's working area to 1 cm2 without compromising performance, making it possible to compare the performance metrics of perovskite solar cells with those of other types of solar cells on the same scale. Recently, You's team and Pan's team kept updating the world record by obtaining certified efficiencies of 25.6% and 25.8% in 2022 and 2023, respectively.

Finds of Gold and Silver Ornaments of the People of the Wielbark Culture From the Area of the So-Called Eastern Zone of the Przeworsk Culture

This paper presents finds of gold and silver ornaments characteristic of the Wielbark culture, originating from the eastern zone of the Przeworsk culture. The distinctiveness of the areas on the right bank of the Vistula occupied by the people of the Przeworsk culture has been repeatedly emphasised in the literature. This distinctiveness primarily manifests in a unique style, combining features typical of the Przeworsk culture with elements derived from other cultural areas, such as the Wielbark culture. The exceptional craftsmanship of goldsmiths is most evident in women’s ornaments, specifically in various forms of pendants and bracelets. The article provides descriptions of fifteen gold and electrum ball and pear-shaped pendants, focusing on their internal variations and decorative elements like granulation or filigree. Additionally, the findings of bracelets from the discussed area are briefly outlined. The issue of sourcing non-ferrous metals required for crafting these ornaments is also explored. No outcrops of these materials were identified in the area occupied by the Wielbark and Przeworsk cultures. It is highly likely that these materials were obtained from the territories of the Roman Empire. However, it remains uncertain whether Roman coins could have been a source of these metals, considering the varying purity levels of coins during different emperors’ reigns. The identification of gold and silver objects within the grave goods of these cultures is hindered by the funeral practice of corpse-burning commonly employed during that era. Most findings exist in the form of small molten metal lumps, making identification impossible. Research and experiments involving the cremation of funeral pyres with grave goods have demonstrated that small non-ferrous metal ornaments almost entirely vanish, either fusing with the funeral pyre or melting to the point of becoming imperceptible. This underscores the possibility of such materials being present in the studied grave sites.

Depletion Calculations for an Integral Small Molten Salt Reactor With Serpent

Abstract The molten salt reactor (MSR) concept is among the Generation IV designs considered feasible for providing clean, safe, sustainable, and economical energy supplies to the world's population. The depletion of fuel for a small modular fluoride molten salt reactor (sm-FMSR) with a closed fuel cycle based on the integral molten salt reactor concept has been investigated using Serpent. The Monte Carlo transport code Serpent has burnup capability and flow features that can be used to model fuel circulation and online fuel addition in an MSR. Three fueling schemes to control Serpent depletion cycles have been simulated and compared: step fueling (SF), continuous fueling with all fission products (FPs) accumulating in the reactor system (CFA), and continuous fueling with insoluble FPs separated from fuel (CFS). CFA and CFS require fewer depletion cycles that are longer in duration than the cycles required by SF, in order to maintain the effective multiplication factor (keff) within a working range over the seven years of the reactor fuel cycle. sm-FMSRs with SF and with CFA require similar quantities of “top-up” fuel, consume similar fuel (fissile) amounts, and result in similar fuel isotopic concentrations if keff is kept within a similar range. However, with separation of insoluble FPs from the circulating fuel, CFS gains a large reactivity worth due to the removal of FP poisons. This allows for reduction of fuel enrichment in both initial and total top-up fuel and leads to savings of a considerable fissile quantity in fueling MSR and in spent fuel. The Serpent depletion calculations require manual arithmetic calculations for adjustment of the Serpent built-in settings before the start of every calculation cycle for all three fueling schemes. Implementation of additional Serpent flow features in changing material volumes and flow constants would facilitate the simulation of the fuel depletion process and allow for more realistic simulations of fuel circulation.

Neutronics study of chloride fuel salts for experimental design of small Molten Salt Reactor

From the Indian perspective, molten salt reactor technology is a promising option for thorium utilization in the third stage of the nation's nuclear programme. Recently, the physics design of a fluoride salt fuelled small molten salt reactor has been initiated as an experimental core to demonstrate the circulating fuel reactor technology. However, the literature suggests that chloride fuel salts have better breeding characteristics, particularly in fast-spectrum MSRs. The thermal-hydraulic and neutronics properties of the chloride fuel salts could considerably differ from that of fluoride. Therefore, the applicability of chloride fuel salts in a small MSR core has been investigated for the neutronics feasibility of the fuel type. In the study, criticality and safety parameters such as neutron multiplication factors and fuel temperature coefficient of reactivity are assessed for three options of chloride-based molten fuel salts. The predicted results for the experimental MSR thermal core fuelled with chloride-based fuel salts are reported in the paper. A brief review on the comparison of chloride fuel salts with the fluoride salts in MSR designs is also presented.

Design considerations of the supercritical carbon dioxide Brayton cycle of small modular molten salt reactor for ship propulsion

Recently, many studies on nuclear-powered ships as replacements for ships using fossil fuels are attracting worldwide attention. Among fourth-generation reactors, molten salt reactors (MSRs) are a suitable candidate as a power source for nuclear-powered ships because of its high efficiency and safety features. In addition, a small modular reactor (SMR) design using MSR can be developed by adopting the supercritical CO2 Brayton cycle (SCBC) as a power conversion system. The SCBC is an appropriate system for MSR-powered ships in terms of its operating temperature and compact size. In this study, we compare the design considerations of SCBC with the design requirements of a reference ship and reactor. Sensitivity studies were conducted with optimization variables, i.e., flow split ratio and pressure ratio, to determine the optimal design of the SCBC. An optimal cycle efficiency of 47.78% was obtained when the flow split ratio was 0.7 and the pressure ratio was 2.94. Finally, the SCBC was compared to a reference design using a pressurized water reactor based steam Rankine cycle. The SCBC was evaluated to be a better design for an MSR-based ship, with approximately 12% higher cycle efficiency than the reference design.

Coupling a small modular molten salt reactor with desalination

To respond to the increasing water demand worldwide, especially in coastal cities and islands, nuclear desalination becomes a potential solution. SmTMSR-400 is a small modular molten salt reactor, which can be easily transported and has inherent safety. This paper analyzes the options of coupling SmTMSR-400 with desalination with parametric studies. SmTMSR-400 is integrated with multi-effect distillation (MED) and reverse osmosis (RO), respectively. In the MED options, the high-pressure, medium-pressure, or low-pressure steam from the steam Rankine power cycle can be used to generate the process steam for desalination. After evaluating and comparing the four options, it is found that: a) the RO option has the best performance of energy utilization and a higher upper limit of water production; b) the RO option is not suitable for water sources containing a large amount of organic matter, and the quality of the water produced is lower than that of the thermal desalination options; c) the low-pressure steam option has the best performance of energy utilization among the MED options, but its water production and power generation cannot be adjusted according to the local demand; d) when the performance of energy utilization, production flexibility, and water quality are all required, the medium-pressure steam option could be an alternative.

Numerical investigation of behaviour of small modular molten salt reactor freeze plug under various reactor operating conditions

Advanced reactors are characterized by passive safety systems to be activated in case of an accident. Molten salt reactors are equipped with a passive emergency draining system. In case of an accident, the reactor shuts itself down, the freeze plug melts due to decay heat, and fuel salt is discharged into the draining tank. The behavior of the freeze plug during liquid-to-solid transition and reactor operation, as well as in the event of an accident was investigated taking two important safety criteria into consideration i.e. the plug shall not melt during normal operation (unwilling opening) and shall passively melt in case of an accident. To evaluate the effectiveness of the freeze plug, computational fluid dynamics method was used. The results showed that draining pipe blocking time is 900 s and 70% of the interior of the freeze plug solidifies in 2700 s. Furthermore, it was concluded that the freeze plug did not cause any unwilling opening. In addition, the freeze plug opening time was calculated as 400 s. Since this value is less than the limiting time of 1100 s which depends on material strength temperature, the freeze plug can be utilized as a passive safety system component.

Grain refinement and mechanism of steel in ultrasound assisted wire and arc additive manufacturing

The small volume molten pool of wire and arc additive manufacturing (WAAM) undergoes complex non-equilibrium solidification process, resulting in the formation of columnar grains that severely limits the mechanical properties of the fabricated components. For refining the microstructure of deposition layers, the optimized ultrasonic equipment and loading methods are installed on a deposition platform, and the ultrasonic energy is coupled synchronously with the WAAM process using ER70S-6 welding wire as the filling material. Experimental results show that high-intensity ultrasound can transform coarse columnar grains into fine equiaxed grains, the area and degree of grain refinement increase with the ultrasonic amplitude. A computational fluid dynamics model of ultrasound assisted WAAM was developed to study the pressure field distribution in the molten pool. The region of acoustic cavitation in molten pools is highly consistent with the region of grain refining, showing that acoustic cavitation is the key factor in changing the grain structure. The collapse of cavitation bubbles generates cyclic alternating local high pressure, resulting in high velocity melt flow near the grain, which causes fatigue fracture of growing columnar grains exceeding the yield strength. A theoretical model is proposed to calculate the maximum length of grain growth under acoustic cavitation, which is in agreement with the experimental statistics of grain size. This work reveals the effect area and mechanism of ultrasound on the rapidly solidified molten pool, and provides a theoretical basis for grain refinement in ultrasound assisted WAAM.

High surface quality additive manufacturing process of titanium alloy with composite heat source

In order to solve the problems of high surface roughness and low dimensional accuracy of titanium alloy metal-wire fuse additive manufacturing, this paper proposes a high surface quality and dimensional accuracy of titanium alloy additive manufacturing with composite heat source process. On the basis of orthogonal experiments, titanium alloy wires with diameter of 0.3 mm Ti-6Al-4V were deposited in a small molten pool by laser and Joule heat source. Thin-walled titanium alloy parts with high surface quality and dimensional accuracy were obtained, and the quality, microstructure, and mechanical properties were tested. The measurement areas are shown that the average roughness Ra is 1.65 μm in the direction deposition, and the dimensional accuracy error is less than 0.28 mm. On this basis, the microstructure and mechanical properties of titanium alloy thin-walled were analyzed. The microstructures are net-like, with microhardness of about 330HV. The ultimate tensile strength of titanium alloy thin-walled parts is 917.56 MPa, and the elongation can reach 20.68%, which is comparable to the strength of casting and forging fracture. The results show that the proposed additive manufacturing process of metal-wire with composite heat source has the potential of further metal AM in high surface quality parts.

Neutron/Gamma Radial Shielding Design of Main Vessel in a Small Modular Molten Salt Reactor

The SM-MSR (small modular molten salt reactor) has a good prospect for development with regards to combining the superiority of the molten salt reactor and modularization technologies, showing the advantages of safety, reliability, low economic cost and flexibility of site selection. However, because its internal structural parts are not easily replaced, and the outer shielding structure is limited, the lifespan of the reactor vessel and its in-reactor shielding design needs to be addressed. In order to find an optimal shielding model with both high fuel efficiency and strong radiation shielding capability, five different design schemes were proposed in this work, which varied in thickness and boron concentration in inner-shielding materials. The neutron/gamma flux and DPA (displacements per atom)/helium production rates were evaluated to obtain an appropriate scheme. Several beneficial results were obtained. Considering the above factors and the actual manufacturing process, 20 cm-thick boron graphite with a 5 wt% Boron-10 concentration combined with a 1 cm-thick Hastelloy barrel was chosen as the in-reactor shielding structure. Outside the reactor, the neutron flux was reduced to 8.33 × 1010 cm−2 s−1, and the gamma flux was decreased to 1.13 × 1011 cm−2 s−1. The vessel/barrel material could maintain a lifespan of more than 10 years, while the burnup depth was 6.25% lower than that of a model without inner-shielding. The conclusions of this research can provide important references for the shielding design and parameter selections of small molten salt reactors in the future.

An assessment of scenarios for transuranic burning and 233U production in a small molten chloride fast reactor

Molten Chloride Fast Reactor (MCFR) attracts more and more attention owing to its significantly hard neutron spectrum and high solubility for actinide trichlorides, making it an appealing option for burning transuranic (TRU) elements discharged from pressurized water reactors (PWRs). Meanwhile, in recent years, the development of thorium fuel cycle has aroused considerable interest worldwide with the purpose of saving uranium reserves and further reducing the production of long-lived minor actinides. A small MCFR incorporating TRU burning and 233U production is proposed in this work in order to evaluate its incineration and production capabilities. By employing an in-house developed tool based on SCALE 6.1, the fuel cycle features of the small MCFR with three fuel loading scenarios, including pure TRU (scenario 1), TRU plus depleted uranium (scenario 2) and TRU plus thorium (scenario 3), are analyzed. The evolution behaviors of main nuclides, reactivity worth, neutron spectra and temperature reactivity coefficient (TRC) are discussed in detail. It is found that the MCFR can burn TRU effectively and the transmutation rates for the three scenarios are 930 kg/GWe/year, 375 kg/GWe/year and 768 kg/GWe/year, respectively, achieving a maximum capability for TRU burning of about 3.7 times the annual TRU production in a 1-GWe PWR with 50 MWd/kgU discharge burnup. Meanwhile, scenario 3 has the highest 233U production capability of about 110.3 kg per year, although it does not offer processing advantages over scenario 1 and scenario 2. The analysis of TRC indicates that the fuel salt TRC and the total core TRC are both strongly negative for all three scenarios owing to the thermal expansion of liquid fuel salt. Finally, a nuclear energy system consisting of both fast and thermal molten salt reactors is proposed and evaluated to establish a closed nuclear fuel cycle with very low radioactive wastes.

Influence of hexagonal scanning strategy island size on microstructure, residual stress, and corrosion behavior of 17-4 PH SS made by L-PBF

17-4 Precipitation-hardened steel has attracted worldwide attention due to its applications. In the manufacture of 17-4 PH SS using SLM, several parameters play an important role. In the present study, the hexagonal island sizes were varied as 1.25-2.5-3.75-5-6.75-7.5-8.75-10 mm to understand the microstructure, microhardness, residual stresses, and corrosion behavior of 17-4 precipitation hardened stainless steel fabricated by laser-powder bed fusion with a scan rotation angle of 90°. The results indicate that the average time per layer decreases as the island size increases. The quality of the surface increased with a decrease in hexagonal island size as scan length reduced. The hardness varied with island size and higher hardness was exhibited due to fine grain size. The medium island size microstructure consists of regular molten pools and lower heat accumulation. Large and small molten pools were observed on the front and side surface respectively for samples with different hexagonal island sizes. Austenite phase was detected in all samples with the highest intensity at hexagonal inside out sample with an island size of 2.5 mm at 43.500°. Both hexagonal samples with 2.5 mm island size and 10 mm samples almost exhibit ɣ-austenite phase in the finer grain size area, as per EBSD orientation maps. The residual stresses increased as the hexagonal island size increased because when a large island size is used, it produces a long scanning track with a weak pre-heating effect, resulting in a high-temperature gradient and high residual stress. Higher corrosion resistance was obtained for 2.5 mm hexagonal scan strategy island size because of finer grain size and lower defects.