Mechanical Behavior Of Alloys Research Articles

Microstructural characterization and mechanical behaviors of Ti-xNb alloys (x = 34–44.at%) fabricated by spark plasma sintering: The role of sintering temperature and Nb content

Microstructural characterization and mechanical behaviors of Ti-xNb alloys (x = 34–44.at%) fabricated by spark plasma sintering: The role of sintering temperature and Nb content

Silicon carbide nanoparticles featured AZ63/BN alloy nanocomposite made by using liquid stir vacuum die cast: characteristics study

ABSTRACT With the unique class, the reinforcements play a precious role during the composite fabrication, expanding the specific properties. The novel research intensively enhances the micro-structural and mechanical behaviour of magnesium alloy (AZ63/3 wt% boron nitride) nanocomposite featured 2, 4, and 6 wt% of nano-size silicon carbide (SiC) particles via liquid state vacuum stir cast route. The exposure of SiC and BN on composite density, voids contribution, changes in AZ91D microstructure, impact toughness, hardness, and stress-strain individuality of AZ63 alloy nanocomposite is evaluated with ASTM policy. The composite composed with 3 wt% BN and 6 wt% SiC proved their identity. It showed the lower contribution of voids-free homogenous dispersion particle results in a maximum impact strength of 14.7J/mm2, hardness of 74HV, and superb tensile strength of 247MPa. This optimum behaviour will be recommended for automotive roof frame applications.

Evading the strength-ductility trade-off dilemma in AA2024 alloy by short-term natural re-aging after T351 temper

In this research, the influence of short-term natural re-aging after T351 temper on the microstructural evolution and mechanical behavior of AA2024 aluminum alloy was investigated. Grain growth occurred in the microstructures of the natural re-aged sample and a large number of Al7Cu2Fe particles were located inside the alpha grains. At the re-aging time of 1440 min, the peaks of XRD were shifted strongly to the right due to the formation of θ′′, S″, θ′, and S′. The results revealed that the precipitation rate was high in the AA2024 alloy during natural aging. With increasing the re-aging time, texture parameters remained almost unchanged. The hardness increased slowly within the first 60 min, then enhanced rapidly between 60 and 2880 min, and finally became stable at around 139 HV between 2880 and 11520 min. When the natural re-aging time increased from 240 to 2880 min, the strengthening trended speed up, viz, the yield strength increased from 226.6 to 357.3 MPa, and the ultimate tensile strength enhanced from 452.2 to 535.5 MPa. Compared to the as-received sample (T351 temper), the ultimate tensile strength of the re-aged sheet improved from 455.5 to 535.5 MPa, the ductility remained unchanged, and the hardness increased from 128.8 to 138.2 HV, which was owing to the acceleration of the precipitation caused by the presence of high-content Al7Cu2Fe particles in the interior of the alpha-aluminum grains in the natural re-aged sample. It was found that the Portevin-Le Chatelier instability of AA2024 alloy was effectively postponed after natural re-aging. With increasing the natural re-aging time, the strain hardening rate of the AA2024 sheet increased. The strengthening of the natural re-aged sample for 1440 and 2880 min was a result of a synergistic effect of precipitation hardening due to the formation of θ′′, S″, θ′, and S′ phases, elimination of Portevin Le-Chatelier instability, and highly efficient load transfer from alpha-aluminum to Al7Cu2Fe. Finally, to use the A2024 alloy produced by natural re-aging for 1440 or 2880 min, two methods were proposed.

Amorphous alloys surpass E/10 strength limit at extreme strain rates

Theoretical predictions of the ideal strength of materials range from E/30 to E/10 (E is Young’s modulus). However, despite intense interest over the last decade, the value of the ideal strength achievable through experiments for metals remains a mystery. This study showcases the remarkable spall strength of Cu50Zr50 amorphous alloy that exceeds the E/10 limit at strain rates greater than 107 s−1 through laser-induced shock experiments. The material exhibits a spall strength of 11.5 GPa, approximately E/6 or 1/13 of its P-wave modulus, which sets a record for the elastic limit of metals. Electron microscopy and large-scale molecular dynamics simulations reveal that the primary failure mechanism at extreme strain rates is void nucleation and growth, rather than shear-banding. The rate dependence of material strength is explained by a void kinetic model controlled by surface energy. These findings help advance our understanding on the mechanical behavior of amorphous alloys under extreme strain rates.

Optimization of Selected Squeeze Casting Parameters on the Mechanical Behaviour of Aluminium Alloy

Aluminum alloy have versatile applications and can be produced via a cost-effective squeeze casting technique. Existing literature has revealed that squeeze casting enhances the mechanical properties of cast products and has the advantage of producing products almost without porosity. However, squeeze casting is faced with some challenges including extrusion segregations, centerline segregation, and oxide inclusion, porosity, blistering, under fill, sticking, hot tearing, case debonding, and shrinkages. In view of minimizing these defects, casting should be done applying optimal parameters that will yield the desired result. The present study focused on the optimization of squeeze parameters of squeeze pressure, pressure duration, pouring temperature, initial die temperature in the production of the aluminium alloy (Al-12%Si). Evaluated responses are yield strength and ultimate tensile strength. The results showed that the process parameters had statistical significance on all properties at 95 % confidence level. Combined interactions of these parameters also presented significant effects on the property responses. Optimum setting for process factors as regards yield strength and ultimate tensile strength were evaluated 150MPa, 15seconds, 700oC and150oC for squeeze pressure, pressure duration, pouring temperature and initial die temperature respectively. The results obtained for the three responses which are yield strength and ultimate tensile strength, were 302.86MPa and 347.72MPa respectively.

TEM and X-ray diffraction studies of structure of TiNi SMA treated by low-energy high-current electron beam

Advanced scientific and technological achievements in the surface engineering of TiNi shape memory alloys are closely related with their mechanical performance. Electron-beam treatments could be applied in order to modify surface properties of smart materials and promote stress-induced martensitic transformations. The fundamental issue of electron-beam processing is residual elastic stresses arising from the ultrafast quenching (∼108 K/s) of thin (∼2–4 μm) surface layers. We report the experimental results on phase composition, structure and residual elastic stresses formed in the binary TiNi SMA irradiated by a low-energy (< 25 keV) high-current (∼ 25 kA) electron beam. Microstructure, fracture mechanisms and phase analysis of the as-cast and deformed tensile specimens have been studied by X-ray diffraction and electron microscopy. After electron-beam treatment, both martensitic B19′ and R phases are found in the near surface layer. The X-ray diffraction studies indicate that compressive stresses in the B2 phase of the irradiated TiNi alloy reach –460 MPa. In the fractured specimen (after tensile test) the residual stresses decrease to –160 MPa and release through the B2→B19′→B2 martensitic transformation. In-depth gradient distribution of the defect substructures responsible for the mechanical behavior of TiNi alloys was revealed.

Research on incremental forming simulation based on an improved constitutive model

The incremental sheet metal forming process, characterized by the step-by-step deformation of sheet metal using a simple die, is classified as a type of plastic deformation technology. This method allows for the formation of complex-shaped parts even without the use of a specialized die. Its notable characteristic lies in its low forming load and high flexibility. To accurately forecast finite element simulation outcomes for the incremental sheet forming of 2024-O aluminum alloy sheets, constructing a precise constitutive model is essential. Typically, the uniform strain range in traditional unidirectional tensile tests does not surpass 0.3, primarily due to the necking phenomenon. This limitation hampers the accurate prediction of the actual large plastic deformation process. To address this issue, a theoretical model describing the stress-strain relationship in metal plastic deformation processes is developed using crystal plasticity theory. The constitutive model for the forming of 2024-O aluminum alloy is then constructed by adjusting the hardening coefficient and hardening index. Utilizing the improved constitutive model, the incremental sheet forming process is simulated using ABAQUS software. Upon comparison with experimental results, it is observed that the Thickness Average Absolute Relative Errors (TAARE) of the adjusted constitutive model at forming angles of 60°, 55°, and 50° are 0.414%, 0.467%, and 0.256%, and The Thickness Root Mean Square Errors (TRMSE) are determined as 0.0121, 0.0116, and 0.0094, respectively. These results indicate that the constitutive model and parameters established in this study can adequately capture the mechanical behavior of 2024-O aluminum alloy during the incremental sheet forming process.

Study of nanoindentation behavior of NiCrCoAl medium entropy alloys under indentation process using molecular dynamics

Abstract The mechanical properties and deformation behavior of CoCrNiAl medium entropy alloy (MEA) subjected to indentation by an indenter tooltip on the substrate are explored using molecular dynamics (MD) simulation. The study investigates the effects of alloy compositions, temperature variations, and ultra vibration (UV) on parameters, such as total force, shear strain, shear stress, hardness, reduced modulus, substrate temperature, phase transformation, dislocation length, and elastic recovery. The findings indicate that higher alloy compositions result in increased total force, hardness, and reduced modulus, with Ni-rich compositions demonstrating superior mechanical strength. Conversely, increasing alloy compositions lead to reduced von Mises stress (VMS), phase transformation, dislocation distribution, and dislocation length due to the larger atomic size of Ni compared to other primary elements. At elevated substrate temperatures, atoms exhibit larger vibration amplitudes and interatomic separations, leading to weaker atomic bonding and decreased contact force, rendering the substrate softer at higher temperatures. Additionally, higher initial substrate temperatures enhance atom kinetic energy and thermal vibrations, leading to reduced material hardness and increased VMS levels. Increasing vibration frequency enlarges the indentation area on the substrate’s surface, concentrating shear strain and VMS with vibration frequency. Higher vibration amplitude and frequency amplify force, shear strain, VMS, substrate temperature, and dislocation distribution. Conversely, lower vibration amplitude and frequency result in a smaller average elastic recovery ratio. Moreover, increased amplitude and frequency values yield an amorphous-dominated indentation region and increased proportions of hexagonal close-packed and body-centered cubic structures. Furthermore, this study also takes into account the evaluation of a material’s ability to recover elastically during the indentation process, which is a fundamental material property.

Impact of edge dislocation and grain boundaries on mechanical properties in CoCrCuFeNi high entropy alloy

This study uses molecular dynamics simulations to explore the mechanical behavior of a CoCrCuFeNi high-entropy alloy (HEA) with Σ5 and Σ13 grain boundaries (GBs) as well as without GBs and dislocation. The analysis focused on understanding the influence mechanisms of these grain boundaries on the mechanical behavior of the HEA. Our findings reveal that the atomic size disparity among the constituent elements induces lattice distortion, leading to deformation in HEAs. The determined elastic constants met Born stability requirements, ensuring mechanical stability across both the examined GBs. Higher elastic moduli were associated with increased strength and stiffness, particularly evident in HEAs with Σ5 GB, surpassing those of non-GB structures. Notably, GB Σ5 demonstrated enhanced strength and hardness, indicated by larger elastic moduli compared with those of non-GB structures. Conversely, GB Σ13 exhibited increased Cauchy pressure and Poisson and Pugh's ratios. The ductility of face-centered cubic HEAs was found to be significantly influenced by the GBs, affecting mechanical properties. The Kleinman parameter highlighted a bending-type bonding with reduced strength at the GBs. Machinability indices indicated high machinability of the CoCrCuFeNi alloy, further enhanced by the presence of the GBs. Direction-dependent parameters underscored the anisotropic nature of the HEA, mitigated by the GBs. Overall, this study elucidates the nuanced influence of different GBs on the mechanical properties of HEAs, offering valuable insights for materials design and applications. The results of this investigation shed light on HEAs with improved mechanical properties via GB engineering.

Mechanical Behavior of Nanotwinned Cu–Ag Alloys with Solute Atomic Gradient Analysis Under the Influence of Twinning Spacing

To investigate the impact of Twinning Boundary Spacing (TBS) on the mechanical characteristics and deformation behavior of nanotwinned Cu–Ag alloys with solute gradient segregation structure during nanoindentation, Voronoi’s method is utilized to create a nanotwinned Cu–Ag alloy model with solute gradient segregation structure. Then, the indentation process of the indenter pressed into the model with varying TBS is simulated using the Molecular Dynamics (MD) simulation, yielding depth-stress curves of the corresponding indenter. According to the findings, yield stresses are lower in Cu–Ag alloys with smaller twin spacing. Grain boundary activities play a governing role in the plastic deformation of the matrix during the small deformation stage, although dislocations also play a part. Grain boundaries have less of an impact on material deformation during the big deformation stage, and dislocations are primarily responsible for the matrix’s plastic deformation. The stacking faults and deformation twin are more prone to occur inside grains with higher solute-atom concentrations compared to grain boundaries with lower solute-atom concentrations.

Impact of scandium and terbium on the mechanical properties, corrosion behavior, and biocompatibility of biodegradable Mg-Zn-Zr-Mn alloys

Magnesium (Mg)-based bone implants degrade rapidly in the physiological environment of the human body which affects their structural integrity and biocompatibility before adequate bone repair. Rare earth elements (REEs) have demonstrated their effectiveness in tailoring the corrosion and mechanical behavior of Mg alloys. This study methodically investigated the impacts of scandium (Sc) and terbium (Tb) in tailoring the corrosion resistance, mechanical properties, and biocompatibility of Mg–0.5Zn–0.35Zr–0.15Mn (MZZM) alloys fabricated via casting and hot extrusion. Results indicate that addition of Sc and Tb improved the strength of MZZM alloys via grain size reduction and solid solution strengthening mechanisms. The extruded MZZM–(1–2)Sc–(1–2)Tb (wt.%) alloys exhibit compressive strengths within the range of 336–405 MPa, surpassing the minimum required strength of 200 MPa for bone implants by a significant margin. Potentiodynamic polarization tests revealed low corrosion rates of as–cast MZZM (0.25 mm/y), MZZM–2Tb (0.45 mm/y), MZZM–1Sc–1Tb (0.18 mm/y), and MZZM–1Sc–2Tb (0.64 mm/y), and extruded MZZM (0.17 mm/y), MZZM–1Sc (0.15 mm/y), MZZM-2Sc (0.45 mm/y), MZZM-1Tb (0.17 mm/y), MZZM-2Tb (0.10 mm/y), MZZM–1Sc-1Tb (0.14 mm/y), MZZM-1Sc-2Tb (0.40 mm/y), and MZZM–2Sc–2Tb (0.51 mm/y) alloys, which were found lower compared to corrosion rate of high-purity Mg (∼1.0 mm/y) reported in the literature. Furthermore, addition of Sc, or Tb, or Sc and Tb to MZZM alloys did not adversely affect the viability of SaOS2 cells, but enhanced their initial cell attachment, proliferation, and spreading shown via polygonal shapes and filipodia. This study emphasizes the benefits of incorporating Sc and Tb elements in MZZM alloys, as they effectively enhance corrosion resistance, mechanical properties, and biocompatibility simultaneously.

The effect of reinforcement particles weight percentage on the mechanical properties and plastic flow behaviour of aluminum alloy 7075 matrix material

AbstractIn the present investigation, an aluminum 7075 based hybrid metal matrix composite has been prepared by utilizing the primary reinforcement element (boron carbide with 9 %, 7 %, 5 %, 3 %, and 1 % weight percentage) and secondary reinforcement particles (silicon carbide with 1 %, 3 %, 5 %, 7 %, and 9 % weight percentage) through the well‐known stir‐casting method. Further, the tensile, hardness and Charpy impact tests were performed on the prepared composite material for mechanical properties evaluation. In addition, an attempt has also been performed to analyze the effect of reinforcement weight percentages (primary and secondary) on the strength coefficient, strain hardening rate and strain hardening exponent of the prepared composite material compositions. The results revealed that sample 1 (aluminum 7075/9 weight percentage boron carbide/1 weight percentage silicon carbide) exhibited the maximum 14.12 percent, 14.25 percent and 19.56 percentage increase in hardness, ultimate tensile strength and yield strength respectively than the matrix material. The strain hardening exponent has been increased with the increase in the weight percentage of silicon carbide. Further, the value of the strength coefficient was decreased with the increase in the weight percentage of boron carbide particles. In addition, stage III hardening was associated with the all developed composite material compositions.

Enhancing microstructural, mechanical, and tribological behavior of AZ31B magnesium alloy through friction stir processing

Surface modification of magnesium alloys was performed using a coating process to optimize their performance. Friction stir processing for preparing magnesium-based high-entropy alloy coatings effectively addressed issues such as oxidation, pores, cracks, and poor coating quality found in existing processes. In addition, it substantially enhanced the hardness and wear resistance of magnesium alloys. The micro-structure and elemental distribution for the cross-section and surface for the magnesium-based high-entropy alloy coating had been studied. The impact of magnesium-based high-entropy alloy upon hardness and wear resistance of the magnesium alloy had been analyzed, focusing on its favorable forming and binding characteristics. Finally, the heat conduction process during friction stir processing were discussed in detail. The theoretical basis for the preparation of magnesium-based high entropy coatings was improved.

Influence of TiCp ceramic reinforcement on Ti6Al4V alloy matrix via spark plasma sintering technique

ABSTRACT The present approach focuses to explore the effect of TiCp nano particulates reinforcement (with various percentages 0%, 0.5%, 1%, 1.5%, 2% & 2.5%) on the microstructure and mechanical behaviour of Ti6Al4V alloys. The spark plasma sintering (SPS) process has been implemented with an applied pressure of 80MPa, sintering temperatures range from 1050°C to 1160°C, with heating rate of 100°C/min, and a dwell time of 5 min at peak temperature to fabricate the nano composites. X-ray diffraction (XRD) and FE-SEM equipped with Energy Dispersive X-ray Analysis (EDAX) were used to examine the newly prepared TMC’s. The sintered Ti6Al4V/TiCp composites showed diverse distributions of TiCp nano-particle in the matrix alloys and were found to exhibit dense, pore-less microstructure. As new phases are developed, the properties of the composite materials’ underwent significant changes.

A study on the microstructure and mechanical behavior of CoCrFeNi high entropy alloy fabricated via laser powder bed fusion: Experiment and crystal plasticity finite element modelling

Additive manufacturing facilitates the design of high entropy alloys (HEAs) with well-performing properties compared to conventional manufacturing methods. However, a significant obstacle to the industrial application of the equimolar CoCrFeNi HEA fabricated through additive manufacturing is the detrimental impact of thermal cracks on its performance. Here, thermal crack-free CoCrFeNi HEAs with enhanced mechanical properties were obtained by optimizing the energy input in laser powder bed fusion (LPBF). The lower energy input resulted in finer grains, leading to simultaneously improved strength and ductility compared to the one fabricated via higher energy input. To understand the relationship between the microstructure and mechanical properties, crystal plasticity element modelling (CPFEM) was employed to accurately model the experimental results. Using the collected constitutive parameters for CoCrFeNi HEA after CPFEM, in-situ tensile modelling was implemented on a converted orientation map of an as-LPBF CoCrFeNi sample. The CPFEM results reveal that the appearance of deformed twins during the initial plastic deformation stage is attributed to a complex distribution of shear strain on the grain boundaries. The interaction between the deformed twins and dislocation motion emerged as the primary deformation mechanisms in the as-LPBF CoCrFeNi HEA, resulting in complex stress and strain distributions. By combining experimental data with modelling techniques, a viable approach to comprehending the detailed deformation mechanism of deformed twins was established.

Experimental tribological and mechanical behavior of aluminium alloy 6061 composites incorporated ceramic particulates using Taguchi analysis

Aluminium metal-matrix composites are broadly employed in industries like aerospace, marine, automobile-sector, and many others, generating a broad research interest. They are preferred for their high strength and low wear rate. This research work is mainly directed towards the fabrication of two types of metal-matrix composite materials using aluminium-alloy 6061(AA6061) as the matrix material and incorporating aluminium oxide (Al2O3), aluminium nitride (AlN), and silicon carbide (SiC) as a reinforcement material. AA6061 has been reinforced with Al2O3 and SiC particulates in AS series composites, while AA series composites, AA6061 has been reinforced with Al2O3 and AlN particulates. This hybrid metal composite was constructed using the stir-casting method. These hybrid composites have been investigated for their physical and mechanical characteristics, viz. density, hardness, impact strength, void content, flexural strength, and tensile strength following the ASTM standards. Tribological characteristics of these hybrid composites were performed by Pin-on-disc (POD) tribometer. Taguchi’s design of experimental technique was applied taking four factors viz. composition, sliding-velocity (SV), sliding-distance (SD), and load, and each having 4 levels. ANOVA was employed to find out meaningful parameters. SEM analysis of worn-surface was executed to find out the dominant wear mechanism. Experimental density was highest for AS42, and AA42 composites and void content were lowest for the same. Mechanical properties viz. density, hardness, impact strength, void content, flexural strength, and tensile strength were higher than the base alloy. From the response table of Taguchi analysis of AS and AA composite, the load factor significantly impacted the specific wear rate (SWR) to follow filler content (FC). It can be followed from the ANOVA table for AS composite that the load factor had a magnificent impact on the SWR. The SV and SD show no significant effect on SWR.

Study on Mechanical Behaviour of AA2014 Aluminium Alloy Blended with Cobalt (Co) and Iron Oxide (Fe2O3)

In order to increase system efficiency, lightweight materials are crucial in the automotive and aerospace sectors. In this work, iron oxide (Fe2O3) and cobalt (Co) were used as reinforcements, with aluminium alloy AA2014 serving as the matrix material. The metal matrix composites were made using the stir casting technique. The proportions of iron oxide and cobalt utilised as reinforcement in the composites were 2.5 wt % and 5 wt %, respectively. On the composite specimen created in accordance with ASTM E8, E9, and E23 standards, the mechanical properties of tensile, flexural, and impact strength were investigated. Investigations were also done on the hardness of the composites. The morphology of the composites was examined using an optical microscope.

Mechanical properties and water vapour corrosion behaviour of Al x CoCrFeNi high-entropy alloys.

Al x CoCrFeNi (x = 0.1, 0.5 and 1) high-entropy alloys (HEAs) were prepared using a spark plasma sintering (SPS) technique combined with aerosol powder. Their microstructure and phase constituents were characterized using an X-ray diffractometer and SEM, and their tensile properties, hardness and compactness were tested. The results show that the crystal structure of the Al x CoCrFeNi HEAs changed significantly with the Al content, from the original single face-centered cubic FCC phase (Al0.1CoCrFeNi) to an FCC + BCC structure (Al0.5CoCrFeNi), and then to FCC + BCC + sigma (σ) phase structures (AlCoCrFeNi). Chemical composition analysis showed that the crystal structure transformation was related to the segregation caused by the increased Al content. The hardness of the Al x CoCrFeNi HEAs increases with increasing Al content, and the hardness of AlCoCrFeNi reaches a maximum of 507.3 HV. The tensile properties of the alloy show a trend of first increasing and then decreasing with increasing Al content, and the yield strength, ultimate tensile strength and elongation of the Al0.5CoCrFeNi alloy reach maximum values of 527.4 MP, 943.3 MPa and 28.2%, respectively. The fracture mechanism of the Al0.1CoCrFeNi and Al0.5CoCrFeNi alloys is typical ductile fracture, while that of the AlCoCrFeNi alloy is cleavage fracture. The compactness of the alloy increases with the Al content. The samples were also subjected to high-temperature water vapour corrosion, and corrosion products such as Al3Fe5O12, CoCr2O4 and NiCr2O4 were found in the Al0.1 and Al0.5 alloys, whereas no oxide peaks were detected using XRD for the Al1 alloy. It was also presumed that a very thin alumina film was generated on the surface of the Al1 alloy, preventing the oxidation of the sample, in combination with the analysis of SEM, EDS and XPS behaviour.

Mechanical behavior of titanium alloys in a dynamic punch test

Mechanical behavior of titanium alloys in a dynamic punch test

Modeling of fatigue behavior in pre-corroded AZ31 magnesium alloy

In this paper, the mechanical and fatigue behavior of pre-corroded wrought AZ31 magnesium alloy was studied. For this purpose, the standard 3.5 wt.% NaCl corrosive solution was used. The samples were immersed for 3–24 h to characterize the effect of immersion time on the mechanical properties of AZ31 alloy. Standard specimens were also immersed for 1–3 h for the fatigue testing. Results of tensile tests showed that thorough the immersion of 0–24 h, the deviation of ultimate tensile stress and yield stress were less than 4 % and 6 %, respectively. Moreover, the deviation of elastic modulus was less than 20 %. Although, the elongation was deviated by 81 % through the immersion of 0–24 h. A drastic decrease was observed in the fatigue lifetime of pre-corroded alloy compared to the bare alloy. As the immersion time increased, the fatigue lifetime decreased. Maximum reduction in fatigue strength occurred when the immersion time was 3 h and the stress amplitude was 82.5 MPa. Fatigue results also showed that the Levenberg-Marquardt was a good method to find the materials' constants, as the maximum and average relative errors were 10.28 % and 2.78 %, respectively. The fatigue fracture surfaces of pre-corroded specimens indicated the brittle fracture. The Basquin model was used for fatigue lifetime prediction. A new model was proposed with a new parameter, initial virtual crack size, to relate the immersion time to the fatigue lifetime using the Paris equation. The fatigue lifetime of 1–3-h pre-corroded AZ31 magnesium alloy was estimated by the new model with acceptable relative errors.