Neutral Salt Spray Test Research Articles

The Effect of Bi on the Kinetics of Growths, Microstructure and Corrosion Resistance of Hot-Dip Galvanized Coatings

This paper presents the results of studies on the growth kinetics, microstructure (SEM/EDS) and corrosion behavior of coatings obtained by hot-dip galvanizing process in baths containing Bi additive. The coatings for testing were produced on low-silicon steel in a Zn bath containing 0.04, 0.12 and 0.4 wt.% Bi. The corrosion resistance of the coatings was determined comparatively in standard Neutral Salt Spray Tests (NSST) (ISO 9227) and sulfur dioxide test (SDT) in a humid atmosphere (ISO 22479). Potentiodynamic tests and electrochemical impedance spectroscopy measurements were conducted. It was found that the addition of 0.04 and 0.12 wt.% Bi reduces the total thickness of the coatings and the thickness of intermetallic layers, while the content of 0.4 wt.% Bi in the bath increases the thickness of the layers forming the coating. Direct corrosion tests (NSST and SDT) and electrochemical tests showed that the addition of Bi to the zinc bath reduces the corrosion resistance of the coatings. The corrosion resistance of the coatings decreases with increasing Bi concentration in the zinc bath. In the microstructure of the coatings, it was found that Bi precipitates mainly on the surface of the coating, but also on the cross-section of the outer layer and ζ intermetallic layer. Bi precipitates, due to their cathodic nature, affect the reduction of the corrosion resistance of the coatings with the increase of their content in the bath.

Monitoring the anticorrosion performance of developed epoxy-based paint formulations on metallic surfaces by electrochemical impedance spectroscopy

Purpose This study aims to investigate the impact of varying solid ratios in epoxy-based formulations on their corrosion resistance. The amounts of epoxy resin in the formulations were kept constant, and the behavior of paints with varying filler ratios was compared. It also examines the tensiometric and rheological properties of these formulations. Design/methodology/approach Three distinct epoxy-based formulations cured with amine compounds were prepared. The formulations underwent various testing protocols to evaluate their performance: coating tests: coated panels with cross lines were exposed to humidity and corrosive atmospheres. Tensiometric Measurements: Conducted using pendant and sessile drop methods. Rheological characterizations: ıncluded flow tests, oscillatory amplitude sweeps and three-interval thixotropy tests. Corrosion resistance assessment: after the panels were immersed in methanol for one week, measurements were taken using electrochemical impedance spectroscopy. Additional tests: neutral salt spray (NSS) and humidity testing. Findings The study observed that the coated panels, after exposure to NSS and humidity testing, demonstrated corrosion resistance within acceptable limits as defined by the ISO 12944-6 standard. Results indicate that the epoxy-based formulations show potential for improvements in paints and coatings, suggesting promising advancements in their anticorrosion performance. Originality/value This research provides insights into how the solid ratios in epoxy-based formulations influence their performance, particularly in terms of corrosion resistance, tensiometric and rheological properties. The findings contribute to the development of more effective epoxy resin-based coatings for industrial applications.

Designing for the chemical conversion coating on AZ91 magnesium alloy by equalising interface potential difference

The formation of intermetallic compounds leads to heterogeneous chemical compositions and galvanic corrosion in alloy materials, which are widely recognised as primary contributors to non-uniform conversion coatings and poor corrosion resistance. This study implements a strategy aimed at regulating surface chemical composition and equalising interfacial potential differences to develop an Al-Mg-V chemical conversion coating on AZ91 magnesium alloy. The surface characteristics and corrosion resistance of the coating are investigated. The results demonstrate that the coating integrates the discretely distributed intermetallic compounds (Mg17Al12) into a continuous and stable cathode phase. The framework structure composed of Mg and Al effectively equalises the interfacial potential differences, reducing the potential difference from 300 mV to 40 mV. The coating enhances the polarization resistance of the AZ91 substrate by approximately 400 times and reduces the self-corrosion current density by three orders of magnitude. After a 186-h neutral salt spray test, no corrosion is observed. The corrosion inhibiting structure formed by V hydroxides/oxides fill the pores and acts as a passivator on the surface, and imparts self-repair capabilities to the coating. The design concept of this chemical conversion coating is expected to be applied to other alloy materials.

Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion Exposure

Anticorrosive organic coatings are usually tested with accelerated weathering methods to assess their anticorrosive performance. The results of lab testing often do not correlate well with results from field testing, which resembles the conditions of actual use more closely. We tested the correlation of the neutral salt spray test (NSS, ISO 9227) and tests for mechanical properties and a 5-year field exposure in four different locations in the atmospheric zone, splash zone and immersion zone using 19 organic coatings for hydraulic steelwork. No correlation was found between the anticorrosive performance under outdoor exposure and the mechanical properties of a coating. The NSS test showed a positive correlation with the results in the field in 6 of 12 cases. For the fresh water testing location in Trier, the correlation proved to be very good. The biggest difference between lab and field testing was observed for zinc-primer-free coatings, which passed in the lab testing and failed in the outdoor testing. This study shows that the NSS test correlates with outdoor exposure only in some cases on a statistically significant level, but the results of NSS testing can be useful in approval testing for protective coating systems using predefined pass/fail criteria.

Enhancing Resistance to Corrosion and Fouling Using Epoxy Coatings with Superhydrophobic Cells

AbstractAs maritime transport becomes increasingly important, metal corrosion results in significant economic losses. Superhydrophobic materials have significant potential for corrosion prevention. However, poor compatibility between superhydrophobic materials and resin reduces the long‐term corrosion resistance. Interfacial strengthening cells (IS‐Cells) are designed to maintain superhydrophobicity and retain active hydroxyl groups participating in resin‐curing. IS‐Cells also contribute to achieving the maze effect. A novel anti‐corrosion IS coating is fabricated by compatible IS‐Cells and epoxy. IS coatings feature smooth surfaces and vertical compactness, protecting against liquid and gaseous corrosive medium. Strong diffusion resistance and extended diffusion distance ensure long‐term corrosion resistance of IS coatings. Approximately 85 µm of IS coatings remain corrosion‐free after 112 days of immersion in the NaCl solution. The low‐frequency impedance, self‐corrosion potential, and self‐corrosion current density are 1.68 × 109 Ω cm2, −0.0708 V, and 5.38 × 10−11 A cm−2, respectively. IS coatings can also withstand 2400 h of neutral salt spray testing without corrosion in the artificial scratches. Due to the electrostatic repulsion between the hydrophobic C–F chains onto IS‐Cells and protein molecules, IS coatings maintain anti‐fouling properties after dry‐wet immersion tests in the natural marine environment for 90 days. IS coatings show great potential for marine anti‐corrosion applications.

Investigation of the Corrosion–Wear Interaction Behavior of 8Cr4Mo4V Bearing Steel at Various Corrosion Intervals

The corrosion–wear coupling damage failure of 8Cr4Mo4V bearing steel under marine atmospheric conditions significantly limits aeroengine bearing applications. The present work aims to investigate the evolution of the corrosion–wear properties of 8Cr4Mo4V bearing steel at varied corrosion intervals and estimate the corrosion–wear interaction (CWI) effect. Neutral salt spray tests combined with tribological experiments were employed to explore the effect of corrosion on wear and the influence of wear on corrosion, and a quantitative characterization method of corrosion–wear interactions was proposed by establishing the component relationships of material losses in the corrosion–wear process. The results indicate that the corrosion rates initially increase and then decrease, ultimately resulting in a pattern characterized by predominant total corrosion and nested localized corrosion. The corroded surfaces tremendously influence the friction coefficient curves at the third stage, and a synergistic acceleration effect exists in the CWI behavior of 8Cr4Mo4V bearing steel under the action of corrosion and wear. A sample corroded for 6 h displayed the significant facilitative effect of corrosion on wear, exhibiting the highest CWI ratio and a greater total mass loss primarily attributed to corrosion. This study offers a significant reference for the quantitative assessment of the tribo-corrosion properties of bearings in a marine atmospheric environment.

Durable one-component polyurea icephobic coatings with energy-saving performance in electrical heating de-icing

Ice formation and accumulation on the surfaces of aircraft, wind turbines, and boat hulls might result in serious economic losses and catastrophic accidents. The development of a new generation of icephobic surfaces has emerged in recent years for anti-icing. However, insufficient durability of the existing icephobic surfaces remains a significant challenge to their applications. In this study, durable one-component polyurea icephobic coatings (OPICs) with a low ice adhesion strength (∼25.3 kPa) were prepared via a solvent-free method by combining the NCO-terminated prepolymer, latent curing agent, and silicone oil. The chemical structure, surface morphology, wettability, mechanical properties, icephobicity, and durability of the OPICs were studied. The optimized design of OPICs with synergistic icephobic mechanisms endowed them with excellent icephobicity and durability. The superior mechanical durability and chemical stability were revealed by the maintaining icephobicity of OPICs even after 3000 continuous Taber abrasion cycles, as well as 50 icing/de-icing cycles, 72 h of NaOH immersion, and 240 h of neutral salt spray test. The effect of OPICs on minimizing the electric power consumption was further investigated by icing wind tunnel. In comparison to the epoxy primer coated and Al alloy coated airfoil surface, airfoil surface coated by OPIC-30 was found to achieve about 43.7 % and 43.9 % energy savings in the keeping entire airfoil surface ice-free, respectively. The one-component polyurea icephobic coatings have great prospects for practical applications that require long-term anti-icing properties.

Effect of multi-element synergistic addition on the microstructure evolution and performance enhancement of laser hot-wire cladded Fe-based alloy

To satisfy the requirements of hardness and corrosion resistance for laser additive manufacturing of hydraulic supports, this study applied the synergistic addition of C, B, Cr, Ni, Nb and Mo elements in Fe-based alloys. The multi-phases, martensite + austenite + ferrite were designed. The microstructure, hardness and corrosion resistance of the coatings were analyzed. Increasing the C and B contents could significantly increase the hardness of the coatings, while the corrosion resistance was decreased. The corrosion resistance of the coatings was determined by the Cr contents. However, increasing the Cr contents to 20.0 wt % resulted in the ferrite structure with lower hardness (21 HRC). The coatings with 0.25 wt % C, 1.2 wt % B and 19.0 wt % Cr showed the optimal matching of hardness (56 HRC) and corrosion resistance (survived in neutral salt spray test≥300h). The resulted coatings were mainly consisted of dendritic structure. Fine lath martensite phase was dominant in the dendrite regions. The interdendritic regions were consisted of nano-sized intermetallics with a mixture of σ+Nb + FeNb + Cr2Nb+(Fe,Cr)2B + NbC compounds. These interdendritic regions (14.2 GPa) showed higher hardness than that of the dendritic regions (7.1 GPa). The high Cr contents with finer dendritic structures were the major mechanisms for the excellent combination of hardness and corrosion resistance. The precipitation and growth mechanisms of the interdendritic phases were elaborated. This work provides a valuable reference for laser hot-wire cladding to prepare Fe-based alloys with high hardness and excellent corrosion resistance.

Anticorrosion mechanism of epoxy coating containing mesoporous resorcinol-formaldehyde hollow nanosphere loaded with 8-Hydroxyquinolin

Mesoporous resorcinol-formaldehyde hollow nanosphere (MRFHN) with erythrocyte like shape was prepared successfully. The average diameter, shell thickness, and specific area of MRFHN are 223 nm, 42 nm, and 73.2 m2/g, respectively. The average loading capacity of 8-Hydroxyquinoline (8-HQ) in MRFHN is 33 % and the sucked 8-HQ can release continuously from MRFHN. MRFHN loaded with 8-HQ (MRFHN@8-HQ) was introduced into epoxy coating to enhance its anticorrosion performance. The results show that epoxy coating pigmented with MRFHN@8-HQ has a higher anticorrosion performance than neat epoxy coating. Especially, epoxy coating containing 4 wt% of MRFHN@8-HQ presents the best anticorrosion performance and self-healing function, and its coating resistance is still maintained at 109 Ω cm2 even after 50-day immersion in 3.5 wt% NaCl solution. Meanwhile, the scratch on coating surface is covered by a thin layer of 8-HQ which can prevent the AA2024 aluminum alloy from corrosion even after 50-day neutral salt spray test. 8-HQ can release from MRFHN and form a compact inhibiting layer on AA2024 aluminum alloy surface, thus the corrosion of AA2024 aluminum alloy is suppressed effectively. MRFHN@8-HQ can be used as a high performance anticorrosion pigment to give epoxy coating a long term protection.

Weathering tests to investigate the durability of anti-corrosion coatings and on-site repair materials

Steel structures are exposed to multiple environmental impacts that lead to reduced durability. Organic paint systems are a resilient mechanism to protect hydraulic steel structures from corrosion. Coatings lead to a decreased corrosion progress at damaged areas. In this work, we investigated the time dependency of undercoating corrosion in the neutral salt spray test in detail by conducting a long-term experiment. Thereby, the fundamental model of corrosion progress was investigated, leading to an increased reliability in approval procedures of coatings and in the choice of test parameters.Additionally, repair materials for on-site repair of damaged coatings were investigated in weathering tests to compare their performance with conventional coatings. These materials are used for short-term repairs of small damaged areas in order to postpone replacement of ailing structures, thus enhancing the durability of steel structures.

A study on the surface responses and degradation mechanisms of epoxy-amine coating subjected to UV accelerated weathering and hygrothermal ageing using ToF-SIMS and FTIR analysis

Epoxy amine coatings were subjected to hygrothermal ageing and accelerated weathering conditions that is comprised of neutral salt spray test and UV accelerated degradation condition. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and Fourier Transform Infrared Spectroscopy (FTIR) were employed to study the surface responses and spectral variation of epoxy amine coatings subjected to different ageing conditions. As a result, principal component analysis (PCA) of ToF-SIMS positive ion spectra illustrated that principal component 1 (PC1) has collected information on a variation of surface responses caused by accelerated weathering and hygrothermal ageing conditions as compared to fresh epoxy amine coatings. On the other hand, principal component 2 (PC2) has distinguished the different surface responses generated on epoxy amine coatings that were subjected to UV accelerated degradation conditions and those that were not. FTIR analysis has demonstrated the hydrolysis and photooxidation of epoxy amine coatings from the growth of two absorption bands at 1709 cm−1 and 1650 cm−1, indicating the formation of carbonyl-containing groups such as ketones, aldehydes, phenyl formates, imine or tertiary amides. This comprehensive analysis provides significant insights into the degradation mechanisms of epoxy amine coatings subjected to corrosion under insulation (CUI) and/or artificial weathering (AW) environment. Understanding these mechanisms is pivotal for industries reliant on epoxy coatings, such as oil and gas, ensuring enhanced performance and extended lifespan of their products under varying environmental conditions. The findings also contribute to the broader field of materials science by offering methodologies and analytical approaches that can be applied to other polymeric coatings and materials.

Preparation of Graphene Oxide/Polymer Hybrid Microcapsules via Photopolymerization for Double Self-Healing Anticorrosion Coatings.

In this work, graphene oxide (GO)/polymer hybrid microcapsule-loaded self-healing agents were prepared via the combination of the emulsion template method and photopolymerization technology. The incorporation of GO in the microcapsule shell not only improved the impermeability, mechanical property, and solvent resistance property of the microcapsules significantly but also endowed the microcapsules with photothermal conversion property. By incorporating GO/polymer hybrid microcapsules in water-borne epoxy resin, a novel kind of anticorrosion coating with a double self-healing property was successfully fabricated. When the coating was scratched, the linseed oil (LO) encapsulated in the microcapsules could fill the crack, and the photothermal conversion property of GO could promote the molecular chain movement of the damaged area under near-infrared (NIR) irradiation to realize the close of the crack. Based on the filling of LO and photothermal conversion-induced scratch narrowing, the "filling" and "close" double self-healing effect can be realized under temporal NIR irradiation, which could lead to the complete recovery of the scratched coating. The |Z|f=0.1Hz value of the damaged coating with GO/polymer microcapsules after double healing was comparable to that of the intact coating, which was about 4 orders of magnitude higher than that of the scratched blank coating and single self-healing coating. As to the neutral salt spray test, the scratched blank coating failed in protection after 100 h, while the healed composite coating did not show any corrosion after 300 h.

Experimental Study on Bearing Capacity Reduction of the Steel Wire-Rings in Flexible Barriers Due to Corrosion

Flexible barriers mitigate geological hazards, relying crucially on wire-ring nets to intercept rockfalls and debris. However, constant exposure to natural environments renders their metal components susceptible to corrosion, affecting the protective efficacy. To investigate the changes in mechanical properties of wire-ring nets resulting from corrosion, the neutral salt spray tests followed by quasi-static tests on uncoated, Zinc-coated, and Galfan-coated high-strength steel wires and wire-rings were conducted. These tests established the correlation between the steel wire's breaking force and its weight loss rate, ultimately facilitating the creation of a pertinent mathematical model. The decline in the breaking force of various types of wire-rings due to corrosion was compared, indicating the influence of corrosion duration, number of winding turns, winding techniques, and coating types on the wire-ring's mechanical performance. Subsequently, the formula for calculating the breaking force of wire-rings in relation to the weight loss rate of the steel wire was derived. Finally, based on the linear relationship between the capacity of single wire-rings and wire-ring nets, a formula was established to estimate the puncturing force of wire-ring nets under different atmospheric corrosion periods. This predictive model provides a basis for the durability design of flexible barrier with different anti-corrosion measures under various atmospheric conditions, and also offers specific insights into maintenance strategy for the existing flexible barriers.

Effect of lithium carbonate solution sealing treatment on corrosion resistance of anodized AA2099-T83 alloy

In order to develop a new surface treatment technology for aluminum−lithium alloys, an AA2099-T83 alloy was anodized in a tartaric−sulfuric acid bath and then post-treated in lithium carbonate (Li2CO3) solutions of different temperature−concentration combinations. The results show that the post-treatment in Li2CO3 solutions can greatly improve corrosion resistance of the anodized alloy (withstanding up to 1300 h of neutral salt spray test). It is found that the sealing process is distinctly different for high-temperature/low-concentration and low-temperature/high- concentration combinations. Specifically, the anodic film is only partially sealed in high-temperature mode but more fully sealed in low-temperature mode. The mechanism for the high corrosion resistance of the treated alloy is ascribed to the barrier effect of the sealing products (i.e., Li−Al−LDH and/or boehmite) on the surface and in the interiors of the anodic film.

Seamlessly embedded microcapsules in self-repairing coatings: Improved compatibility and enhanced corrosion resistance recovery

Microcapsules, with polyether amine as the core repairing agent and polyether amine-cured epoxy as the shell, were prepared via the multiple emulsion polymerization and applied in an epoxy/polyether amine coating system on carbon steel surfaces. The microcapsules and the coating substrate have the same composition and are seamlessly connected by chemical bonds, akin to the direct injection of liquid healing agents into the substrate. When the repairing agent flows out, it will crosslink and cure with the epoxy groups in the substrate to achieve no difference self-repair. The characteristics of microcapsules were studied by scanning electron microscope (SEM), Fourier transform infrared (FTIR) and Thermal gravimetric (TG). The mechanical properties and corrosion resistance recovery of coatings loaded of coatings with different weight percentages of loaded microcapsules were investigated using tensile testing, electrochemical impedance spectroscopy (EIS) and neutral salt spray test (NSS). Results indicate that the 7 wt% microcapsules composite coating shows a 37.7 % increase in tensile strength and a 71.4 % increase in fracture toughness over pure epoxy coating. After immersing in saltwater for 7 days, the scratch sealing efficiency can reach 99.85 %. The coating system not only improved the compatibility between microcapsules and the substrate, but also enhanced the toughness of thermosetting brittle epoxy materials, giving it long-lasting anti-corrosion capability.

Self‐healing polyurethane anticorrosive coatings based on alkyd resin microcapsules

AbstractIn this paper, self‐healing microcapsules were prepared by in situ polymerization using poly(vinyl alcohol) as the emulsifier, urea‐formaldehyde resin as the shell material, and alkyd resin as the core material. The average diameter of the obtained microcapsules was about 20 μm and the encapsulation rate of alkyd resin was 50.7 wt.%. The self‐healing coating was prepared by adding 5 wt.% of microcapsules to the pure polyurethane coating and then coated on AA2024‐T3 substrate. The self‐healing effect was evaluated by scanning electron microscopy. Electrochemical impedance spectroscopy tests and neutral salt spray tests confirmed that the self‐healing coating had good anticorrosion properties.

The Effect of Spray Testing Condition on the Corrosion Performance of Hydrothermally Sealed Anodic Oxide on a 5005 Aluminum Alloy: Comparison between Neutral Salt Spray, Acetic Salt Spray and Prohesion Testing Methods

In this work, the output of different accelerated tests on anodic aluminum oxide (AAO) coatings developed on AA5005 aluminum alloy (sulfuric acid bath and hydrothermal sealing) has been investigated. In particular, three corrosion testing methods, namely neutral salt spray test (NSS), acetic acid salt spray (AASS) and prohesion test, have been performed on the sealed AAO-coated panels in order to investigate the reliability of the obtained results to the electrochemical impedance ones. NSS and prohesion testing results are found to align with findings from electrochemical impedance spectroscopy (EIS). The acetic salt spray test appears to be highly corrosive, causing rapid depletion of the oxide layer’s protective capabilities, as indicated the EIS analysis. The findings suggest that the deterioration of the oxide layer’s barrier properties appears to be more pronounced than what optical image analysis suggests.

Roles of Al and Mg on the Microstructure and Corrosion Resistance of Zn-Al-Mg Hot-Dipped Coated Steel.

In this work, a novel zinc-aluminum-magnesium (Zn-Al-Mg, ZM) coated steel was prepared using the hot-dip method. The microstructure and corrosion resistance of the ZM-coated steel were investigated. Compared to the conventional galvanized steel (GI), the ZM coating demonstrated a distinctive phase structure, consisting of Zn phase, binary eutectic (Zn/MgZn2), and ternary eutectic (Zn/Al/MgZn2). The corrosion resistance of the ZM-coated and GI-coated steels was evaluated by neutral salt spray test (NSST), polarization and electrochemical impedance spectroscopy (EIS). The results indicated that ZM-coated steel provided superior long-term corrosion protection in a NaCl environment compared to GI-coated steel. The scanning vibrating electrode technique (SVET) proved to be an effective method for investigating the evolution of the anodic and cathodic on the local coating surface. GI-coated steel exhibited a potential and current density distribution between the cathodic and anodic sites nearly three orders of magnitude higher than that of ZM-coated steel, suggesting a higher corrosion rate for GI-coated steel.

Construction of wear resistant superhydrophobic structure without degrading the surface mechanical properties of alloy layer

The vulnerability of superhydrophobic surface structures frequently leads to a loss of their superhydrophobicity under friction, significantly restricting their broad-scale applicability. The preparation of alloy layers emerges as an effective strategy to enhance the mechanical properties of metal surfaces. The construction of superhydrophobic structures without loss of mechanical properties of alloy layer is expected to lead to the preparation of superhydrophobic surface with excellent wear resistance. In this study, a superhydrophobic surface with excellent hardness and wear resistance was successfully prepared by a two-step process of electrospark deposition and anodization. The superhydrophobic surface maintained superhydrophobicity under long distance friction. Firstly, alloy layer with micron bulges and excellent mechanical properties was constructed on the metal surface by electrospark deposition, which was then slightly anodized to create hierarchical micro-nano bulges rather favourable to superhydrophobicity, and anodization did not degrade mechanical properties of the surface. The surface is provided with excellent superhydrophobicity after modification with fluorosilane. SEM, 3D profilometer and roughness tester were adopted to explore microscopic morphology of the sample surfaces. XPS and FTIR were used to explore chemical components of the sample surfaces. The element distribution of the sample surfaces was analysed through EDS, and wettability of the sample surfaces was explored through the contact angle test. The hardness test and wear test were applied to explore mechanical properties of the sample surfaces. It was proved through linear friction, droplet impact, hammering and knife scratch that the superhydrophobic surface could maintain good superhydrophobicity under multiple forms of mechanical destruction, while the neutral salt spray test, electrochemical tests and acid and alkali soaking test proved the excellent property of corrosion resistance of the superhydrophobic surface. In addition, the prepared superhydrophobic surface also features an excellent self-cleaning property.

Comparative Study of Anti-Corrosion Properties of Different Types of Press-Hardened Steels.

Hot stamping (or press hardening) is a new technology that is widely used in the production of advanced high-strength steel parts for automotive applications. Electrochemical measurements, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), and accelerated corrosion tests (the neutral salt spray test and periodic immersion test) were conducted on press-hardened samples produced from uncoated (cold-rolled and cold strip production (CSP) hot-rolled) and Al-Si-coated press-hardened steels to elucidate their distinct anti-corrosion mechanisms. The cross-sectional micromorphology and element distribution of three types of press-hardened steels after a neutral salt spray test were observed using scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX). The corrosion resistance of Al-Si-coated press-hardened steel was found to be significantly diminished following the hot stamping process due to the presence of microcracks and elevated iron content in the coating subsequent to austenitizing heat treatment. On the other hand, the corrosion resistance of uncoated press-hardened sheets produced from cold-rolled and CSP hot-rolled press-hardened steel was found to be proximal due to their nearly identical composition and microstructure (fully martensite) after the hot stamping process. Considering the high efficiency and energy-saving properties of hot-rolled press-hardened steel, it holds the potential to replace cold-rolled and even aluminum-silicon-coated press-hardened steel in automobile manufacturing.