Reduction In Ultimate Tensile Strength Research Articles

Investigation of Microstructures and Tensile Properties of 316L Stainless Steel Fabricated via Laser Powder Bed Fusion.

In this study, a thorough investigation of the microstructures and tensile properties of 316L stainless steel fabricated via laser powder bed fusion (L-PBF) was done. 316L stainless steel specimens with two different thicknesses of 1.5 mm and 4.0 mm fabricated under similar conditions were utilized. Microstructural characterization was performed using optical microscopy (OM) and scanning electron microscopy (SEM) equipped with electron backscatter diffraction (EBSD). Melt pools and cellular structures were observed using OM, whereas EBSD was utilized to obtain the grain size, grain boundary characteristics, and crystallographic texture. The 1.5 mm thick sample demonstrated a yield strength (YS) of 538.42 MPa, ultimate tensile strength (UTS) of 606.47 MPa, and elongation to failure of 69.88%, whereas the 4.0 mm thick sample had a YS of 551.21 MPa, UTS of 619.58 MPa, and elongation to failure of 73.66%. These results demonstrated a slight decrease in mechanical properties with decreasing thickness, with a 2.4% reduction in YS, 2.1% reduction in UTS, and 5.8% reduction in elongation to failure. In addition to other microstructural features, the cellular structures were observed to be the major contributors to the high mechanical properties. Using the inverse pole figure (IPF) maps, both thicknesses depicted a crystallographic texture of {001} <101> in their as-built state. However, when subjected to tensile loads, texture transitions to {111} <001> and {111} <011> were observed for the 1.5 mm and 4.0 mm samples, respectively. Additionally, EBSD analysis revealed the pre-existence of high-density dislocation networks and a high fraction of low-angle grain boundaries. Interestingly, twinning was observed, suggesting that the plastic deformation occurred through dislocation gliding and deformation twinning.

Tailoring Multiple Strengthening Phases to Achieve Superior High-Temperature Strength in Cast Mg-RE-Ag Alloys.

Mg alloys with excellent high-temperature mechanical properties are urgently desired to meet the design requirements of new-generation aircraft. Herein, novel cast Mg-10Gd-2Y-0.4Zn-0.2Ca-0.5Zr-xAg alloys were designed and prepared according to the advantages of multi-component alloying. The SEM and XRD results revealed that the as-cast microstructures contained α-Mg grains, β, and Zr-containing phase. As Ag rose from 0 wt.% to 2.0 wt.%, the grain size was refined from 40.7 μm to 33.5 μm, and the β phase significantly increased. The TEM observations revealed that the nano-scaled γ' phase could be induced to precipitate in the α-Mg matrix by the addition of Ag. The stacking sequence of lamellar γ' phases is ABCA. The multiple strengthening phases, including β phase, γ' phases, and Zr-containing particles, were effectively tailored through alloying and synergistically enhanced the mechanical properties. The ultimate tensile strength increased from 154.0 ± 3.5 MPa to 231.0 ± 4.0 MPa at 548 K when Ag was added from 0 to 2.0 wt.%. Compared to the Ag-free alloy, the as-cast alloy containing 2.0 wt.% Ag exhibited a minor reduction in ultimate tensile strength (7.0 ± 4.0 MPa) from 498 K to 548 K. The excellent high-temperature performance of the newly developed Mg-RE-Ag alloy has great value in promoting the use of Mg alloys in aviation industries.

Microstructure evolution and mechanical properties of friction stir welded Fe50Mn30Co10Cr10 high-entropy alloy

Metastable Fe50Mn30Co10Cr10 HEA has a significant strength-ductility synergistic effect and a wide application prospect in nuclear power. The present work reports the microstructure evolution and tensile behavior of friction stir-welded joints for Fe50Mn30Co10Cr10 high entropy alloy (HEA) at various rotational speeds. Defect-free welds of Fe50Mn30Co10Cr10 alloy were obtained by a W-Re alloy welding tool. Significant grain refinement occurs in the nugget zone, where the most of HCP phases in the base metal transformed into FCC phase. Additionally, strain-induced Σ3 mechanical twins are generated in the FCC austenite grains. The microstructure of thermo-mechanically affected zone exhibited multiple deformation mechanisms, including stacking faults, martensite lath, martensite variants, and reverse transformation. The microhardness of the joint primarily depends on the grain size of the FCC phase and the fraction of twins and HCP phase. In the nugget zone of the joint welded at 300 rpm, a high microhardness zone ranging from 266.7 to 310 HV was detected. While the reverse transformation and fresh twinning in the joint at 600 rpm contribute to the enhancement of tensile properties, the increase in grain size and ε martensitic fraction have resulted in a noteworthy reduction in ultimate tensile strength (UTS) and elongation (EL). Conversely, the joint of 300 rpm exhibited optimum UTS and EL owing to the grain refining after FSW and the transformation induced plasticity (TRIP) effect. These insights confirm that FSW is an ideal approach for achieving superior joint performance in dual-phase HEAs.

A structured approach to the determination of residual stresses in an epoxy-amine coating and the influence of thermal ageing on the thermomechanical properties, residual stresses and the corresponding failure modes of coating

The purpose of this research was to develop a structured approach for the calculation of residual stresses in organic coatings through the experimental determination of thermomechanical properties of the epoxy-amine coating. The feasibility of this proposed method was validated by the presence of cracks on epoxy amine coating subjected to isothermal ageing at 180 °C for a period of 8 weeks, followed by thermal shock by water quenching at 0 °C, when the tensile strength of coating (8.00 MPa) was surpassed by the accumulated residual stress in the coating (9.66 MPa). The influence of thermal ageing on the thermomechanical properties, residual stresses and the corresponding failure modes were also evident. Significant variation of thermomechanical properties such as the increase in Tg from 77.60 °C to 120.50 °C, reduction of thermal expansion coefficient from 51.74×10−6°C−1 to 40.27×10−6°C−1, reduction of elastic modulus from 1600 MPa to 1400 MPa, and reduction of ultimate tensile strength from 27.00 MPa to 8.00 MPa after thermal ageing were observed. These variations have ultimately led to the increase of residual stresses in coatings that has resulted in the formation of cracks.

Fracture Toughness of Ti6Al4V/Cp-Ti Multi-Material Produced via Selective Laser Melting

Multi-materials can locally enhance the properties of products to improve their performance. In some cases, it might be necessary to improve the fracture toughness properties locally. This work is devoted to investigating the fracture toughness of multi-material Ti6Al4V/Cp-Ti specimens produced via laser powder bed fusion (L-PBF). The powder feeding and distributing system of the L-PBF machine was modified for programmable dual-powder feed capability. The multi-material Ti6Al4V/Cp-Ti samples analyzed in this work are layered materials, where the Ti6Al4V alloy serves as the base material and Cp-Ti is present as separate layers. Samples of this type rely on the principle of crack inhibition, where fracture energy is dissipated in the more ductile Cp-Ti layers. Two variants of alternating ductile layers were studied. The microstructure of the materials and interfacial zone were analyzed using an optical microscope. Chemical composition was examined with a scanning electron microscope. The size of the interfacial zone in the multi-material averaged between 250 and 300 μm. A comparison of the tensile tests results with the literature data (of relatively pure Ti6Al4V alloy) reveals that there is a minor reduction in ultimate tensile strength and elongation. The obtained results confirm the possibility of locally increasing fracture toughness through the creation of a multi-material structure using L-PBF.

Mechanical, thermal, and electrical properties of amine‐ and non‐functionalized reduced graphene oxide/epoxy carbon fiber‐reinforced polymers

AbstractGraphene and its related materials are increasingly applied in fiber‐reinforced polymers to tailor their material properties for high performance composites. Yet, the use of graphene derivatives that underwent a plasma functionalization process is not well understood. This study uses 1.50 wt.% of unfunctionalized (rGO) or plasma‐treated reduced graphene oxide with amine‐functionalities (frGO) in an epoxy matrix to prepare unidirectional pre‐impregnated carbon fibers. The material characteristics of the graphene‐modified carbon fiber‐reinforced polymers (g‐CFRP) are compared to the neat carbon fiber‐reinforced polymer (CFRP). Both g‐CFRP configurations exhibit a higher void content than the neat CFRP. No significant difference between the CFRP and the g‐CFRPs is observed with respect to the Young's modulus, glass transition temperature, storage modulus, specific heat capacity, thermal conductivity at room temperature, and in‐plane electrical conductivity. Yet, a reduction in ultimate tensile strength of up to −13% is noted. In addition, the apparent interlaminar shear strength and transverse electrical conductivity are increased by up to +12% for the rGO‐CFRP and +52% for the frGO‐CFRP. This knowledge will support the selection of additives for fiber‐reinforced polymers for, for example, lightning strike protection in aircrafts, sensory materials, electromagnetic interference shielding or heat transfer elements.

Revealing the microstructural evolution and its influence on mechanical properties of heterostructured steel fabricated by laser melting deposition

A series of heterostructured materials with variable ratio of 316 powders in 18Ni300 powders were prepared by laser melting deposition (LMD). The microstructural evolution and its influence on tensile features were explored before/after aging treatment or solution-aging treatment. The results indicated that the fraction of γ phase was increased gradually with increasing 316SS, and dislocation caused by the deformation could be migrated and annihilated within the region of γ phase, second phase strengthening could contribute to excellent elongation for 18Ni300 maraging steel. The elongation of the AF4 sample was 235.2% higher than that of the AF0 sample when a 37.5% reduction in the ultimate tensile strength occurred. In addition, thermal stress could exist in the as-cladded sample, an appropriate heat treatment could release the thermal stress and precipitate nanoscale intermetallic compound. Their synergistic effect could contribute to overcoming the strength-elongation trade-off. A relatively ideal sample, a discontinuous γ phase surrounded by α phase, which displayed high strength of 1678.4 MPa with high elongation of 10.9% after solution-aging treatment. Compared with laser cladded 18Ni300 maraging steel, a 41.7% increment in the elongation was obtained at the cost of 11.3% reduction in ultimate tensile strength.

Improving the ductility and toughness of nano-TiC/AZ61 composite by optimizing bimodal grain microstructure via extrusion speed

In this study, the nano-TiC/AZ61 composites with different heterogeneous bimodal grain (HBG) structures and uniform structure are obtained by regulating the extrusion speed. The effect of HBG structure on the mechanical properties of the composites is investigated. The increasing ductility and toughening mechanism of HBG magnesium matrix composites are carefully discussed. When the extrusion speed increases from 0.75 mm/s to 2.5 mm/s or 3.5 mm/s, the microstructure transforms from uniform to HBG structure. Compared with Uniform-0.75 mm/s composite, Heterogeneous-3.5 mm/s composite achieves a 116.7% increase in ductility in the plastic deformation stage and almost no reduction in ultimate tensile strength. This is mainly because the lower plastic deformation inhomogeneity and higher strain hardening due to hetero-deformation induced (HDI) hardening. Moreover, Heterogeneous-3.5 mm/s composite achieves a 108.3% increase in toughness compared with the Uniform-0.75 mm/s composite. It is mainly because coarse grain (CG) bands can capture and blunt cracks, thereby increasing the energy dissipation for crack propagation and improving toughness. In addition, the CG band of the Heterogeneous-3.5 mm/s composite with larger grain size and lower dislocation density is more conducive to obtaining higher strain hardening and superior blunting crack capability. Thus, the increased ductility and toughness of the Heterogeneous-3.5 mm/s composite is more significant than that Heterogeneous-2.5 mm/s composite.

ANALYSING EFFECT OF QUENCHING AND TEMPERING INTO MECHANICAL PROPERTIES AND MICROSTRUCTURE OF 304-SS WELDED PLATES

The present work deals with analysis of mechanical performance and microstructural appearance of quenched and tempered SS-304 welded joints made by MIG welding technique. Since welding involves a critical solidification and thereby lots of internal stresses. Hence, heat treatment becomes important for removing stresses. In the present work, two SS-304 welded plates were heat treated. First plate was in quenched condition, and another was in tempered state. In both the plates, mechanical properties like tensile strength, impact strength, and hardness were analyzed. In addition, the microstructural attributes of base metal, heat affected zone and welded joints in both the welded plates were analyzed through optical microscope. The fractography analysis was also carried out in this study to get information about failure characteristics of samples after tensile testing. A significant change in mechanical properties, such as, 150% improvement in toughness, 7% reduction in weld-zone hardness, 3% improvement in yield strength and 6% reduction in ultimate tensile strength was obtained after tempering work. Also, the tempering process had reformed the grain structure by creating twins in base metal, and lathy δ ferrite &amp; γ+δ lamella in HAZ. The martensite formed in quenched specimen had been completely recovered into fine γ+δ matrix.

Investigation of microstructure and mechanical properties of Cu-Ni alloy processed by equal channel angular pressing

The Copper-Nickel alloy, C70600, was subjected to severe plastic deformation by the equal channel angular pressing (ECAP) technique. The material was pressed at room temperature along route BC for eight passes. Microstructural analysis and mechanical characterization of the material were done for each of the ECAP pass samples. The initial homogenized material having equiaxial grains of average grain size 75 µm was reduced to 20 µm after eight ECAP passes. Electron backscatter diffraction data presented an increase in low angle grain boundaries with an increase in the number of ECAP passes. Initially, the ultimate tensile strength and the hardness increased by 56% and 94% respectively. After the fifth ECAP pass, a drastic reduction in ultimate tensile strength and ductility was witnessed. Hardness value remained constant after the fifth ECAP pass. Fractography analysis indicate the ductile mode of fracture with reduced dimple size at higher ECAP passes.

A multi modal approach to microstructure evolution and mechanical response of additive friction stir deposited AZ31B Mg alloy

Current work explored solid-state additive manufacturing of AZ31B-Mg alloy using additive friction stir deposition. Samples with relative densities ≥ 99.4% were additively produced. Spatial and temporal evolution of temperature during additive friction stir deposition was predicted using multi-layer computational process model. Microstructural evolution in the additively fabricated samples was examined using electron back scatter diffraction and high-resolution transmission electron microscopy. Mechanical properties of the additive samples were evaluated by non-destructive effective bulk modulus elastography and destructive uni-axial tensile testing. Additively produced samples experienced evolution of predominantly basal texture on the top surface and a marginal increase in the grain size compared to feed stock. Transmission electron microscopy shed light on fine scale precipitation of Mg_{17}Al_{12} within feed stock and additive samples. The fraction of Mg_{17}Al_{12} reduced in the additively produced samples compared to feed stock. The bulk dynamic modulus of the additive samples was slightly lower than the feed stock. There was a sim, 30 MPa reduction in 0.2% proof stress and a 10–30 MPa reduction in ultimate tensile strength for the additively produced samples compared to feed stock. The elongation of the additive samples was 4–10% lower than feed stock. Such a property response for additive friction stir deposited AZ31B-Mg alloy was realized through distinct thermokinetics driven multi-scale microstructure evolution.

A fully coupled chemo-mechanical cohesive zone model for oxygen embrittlement of nickel-based superalloys

For nickel-based superalloys subjected to high temperatures and oxygen-rich environments, mechanical loading in combination with oxygen diffusion along grain boundaries leads to an acceleration of crack propagation. To account for these phenomena, a fully coupled thermodynamically consistent chemo-mechanical modeling framework for stress-assisted oxygen embrittlement of grain boundaries in polycrystals is proposed. We formulate an extended cohesive zone model where the grain boundary strength is reduced by the presence of oxygen and the oxygen diffusion is enhanced by tensile mechanical loading. We show that the model can qualitatively predict experimental results such as: reduction of ultimate tensile strength and accelerated crack growth due to dwell time combined with mechanical loading and saturation of crack growth rates for increasing environmental oxygen pressure levels. In addition, numerical simulation results of intergranular crack growth are shown for a 2D polycrystalline structure. An emphasis is put on the difference in cracking behavior after dwelling with or without mechanical loading.

Mechanical properties of wood polymer composites made of sawdust waste and recycled high density polyethylene

This work investigated the mechanical properties of wood polymer composites (WPCs), which were made using recycled high density polyethylene (HDPE) and sawdust waste. Degraded HDPE was used as a coupling agent. Different blends of virgin (vPE) and recycled (rPE) poly ethylene's with various ratio (100/0, 75/25, 50/50, 25/75 and 0/100) were prepared in order to be used as matrices. PE blends and composites were prepared by melt-mixing technique using mini twin-extruder. Mechanical properties such as ultimate tensile strength (UTS), impact strength and Shore hardness were determined for vPE, rPE, PE blends and PE composites. The mechanical properties of PE blends and composites were mainly depended on the composition of its matrices. Presences of degraded HDPE as a coupling agent played an important role on the mechanical properties of WPCs. Increasing the rPE content in the blend composition displayed decrease in the UTS and impact strength properties. The incorporation of only sawdust into vPE, rPE and PE blends matrices caused reduction in UTS and impact strength properties and an increase in Shore hardness. UTS, impact strength and Shore hardness for all WPCs were improved when 5% degraded PE was added. UTS and Shore hardness for composites with 5% degraded PE were higher than that of its matrices. The properties of PE composites were better than that of PE blends, which suggesting that using rPE to attain blends with vPE and then making composites appears to be more preferable than making only PE blends.

Effects of process interruptions on microstructure and mechanical properties of three face centered cubic alloys processed by laser powder bed fusion

Many factors can influence the thermal history during laser powder bed fusion (L-PBF) that contribute to the microstructure and mechanical performance of produced components. These factors can include process parameters, geometry, feedstock characteristics, and more. In this work, we report on the effect that process interruptions have on the thermal history during L-PBF fabrication of simple geometries made out of three alloys of interest: AlSi10Mg, Inconel 718 and Inconel 625. Systematic experiments were carried out with programmed process interruptions lasting one hour and simulating a stop to refill the system with powder, or an unexpected power outage. Specimens produced through these experiments enabled studying microstructural differences using microscopy techniques, and the evaluation of tensile and hardness properties when compared to uninterrupted controls. The findings from this study indicate that there were no distinguishable microstructural differences from interrupted specimens and uninterrupted controls for all three materials. Also, although Inconel 718 interrupted specimens showed a slight reduction in ultimate tensile strength and elongation, these properties remained essentially unchanged for AlSi10Mg and Inconel 625. Although a more comprehensive study is still required that accounts for the effect of thermal post-processing and other factors, the results described here provide several observations of the potential effects of process interruptions, and the implications towards process validation and quality assurance of L-PBF.

Effect of plasma processed Ti-Al coating on oxidation and tensile behavior of Ti6Al4V alloy

The investigation of the oxidation resistance and tensile behavior of aluminide coated and uncoated Ti6Al4V at room temperature and at 600 °C was carried out. Ti-Al coating was developed on Ti6Al4V by Hot-dip Aluminizing technique followed by solution treatment (900 °C/1 h), quenching in water and ageing treatment (500 °C/6 h). For a comparative analysis, the diffusion heat treatment was performed with and without oxygen plasma environment. The diffusion treatment without oxygen plasma is referred as thermal treatment while the diffusion treatment with oxygen plasma is referred as plasma treatment. The cyclic oxidation test was carried out for uncoated samples, thermally treated (THT samples) and plasma treated samples (PAHT samples) at 600 °C for 120 h. Significant improvement in the oxidation resistance was observed for coated samples. Weight gain during oxidation studies in PAHT samples is almost 100 times less than uncoated samples and 8 times less than THT samples. The tensile test conducted at room temperature and at 600 °C showed marginal reduction of Ultimate tensile strength (UTS) and Yield strength (YS) of substrate for PAHT samples and THT samples. Plasma processing yields nanocrystalline coatings which have been found to improve oxidation resistance and would help address oxidation issues in gas turbine applications.

E EXPERIMENTAL &amp; NUMERICAL STUDY OF BUCKLING BEHAVIOR FOR STAINLESS STEEL 304 ALLOY COLUMNS UNDER DYNAMIC LOADS

In the present research the effect of corrosion on buckling behavior of 304 stainless steel with increasing of compressive dynamic loads was studied. There are long types of the columns were used. For compression test, there are 24 columns specimens were used in the dynamic axis, 12 columns tests were carried out with increasing in the dynamic axis of compressive load, while for the corrosion test was performed by using 12 specimens were buried for two months under the ground before tested them. The digital gauge was employed at the distance about 0.7 for the column length at the fixed end of column. has alarm system was used to define critical buckling and to avoid the failure of the specimen and installed at the distance equal to 0.7 of the column length from fixed end. The empirical results showed that the effect of negatively corrosion on mechanical properties of alloys with 2.53% reduction of ultimate tensile strength comparing with non-corroded specimens, in the other hand the corrosion will reduce the critical buckling load by 6% for two months. The experimental results comparing with the standard theories of the buckling behavior and with the finite element (ANSYS) results to verify the mathematical model.

The statistical analysis of tensile and compression properties of the as-cast AZ91-X%B4C composites

The statistical distribution of the ultimate tensile strength (UTS) and compression strength (UCS) values of the cast B4C containing Mg matrix composite and its matrix alloy (AZ91) was assessed using different amounts of B4C (1, 3, 5, and 7 wt%) by the use of two-parameter Weibull analysis. Microstructural observations of the composites revealed a reduction in the amount of the Mg17Al12 intermetallic phase, a rather clean interface between B4C particles and the matrix and a good distribution of the B4C reinforcement in the matrix. It was found that the addition of B4C particles to the matrix alloy resulted in the reduction in UTS and elongation values, whereas the compressive strength enhanced slightly. Weibull modulus of the castings was found to be ~ 10 for AZ91 alloy, falling to ~ 6 in the AZ91–7%B4C, but in the compression test, it varied from ~ 52 to ~ 87. The fracture study of the tensile specimens revealed that oxide films and porosity are the main factors for the decreased strength and scattered results, which are increased by using more B4C contents. If the composite can be manufactured with less amount of oxides, it is seen to be more reliable for compressive applications.

Mechanical properties of strain annealed metal amorphous nanocomposite (MANC) soft magnetic material

Metal amorphous nanocomposites (MANCs) offer lower losses than silicon steels and higher saturation inductions than amorphous alloys. Their application in motors will require a detailed understanding of their mechanical properties. Co74.6Fe2.7Mn2.7Nb4Si2B14 was studied by nanoindentation and tensile testing to determine hardness, elongation, Young's modulus, ultimate tensile strength (UTS), and Poisson's ratio. Young's modulus was observed to increase with crystallization at 50 MPa, and then decrease when annealing under applied stress. Annealing at even higher stress resulted in no significant change in Young's modulus. This trend was replicated in nanohardness results. The UTS and elongation decrease with crystallization and show a large increase in standard deviation. Reduction in UTS and elongation has been attributed to embrittlement, as well as the high surface roughness of the ribbon material. Poisson's ratio remained relatively constant at 0.31–0.33 for all samples. X-ray diffraction (XRD) was performed on annealed samples, revealing fine nanocrystals. Profilometry indicates significant surface roughness, which contribute to reduction of UTS and elongation. Hardness, UTS, and elongation compare favorably to existing materials, but embrittlement of the material needs to be addressed to allow use in electric motor applications.

Finite Element Method Analysis of Normal and Corrosion Buckling with ANSYS17 Program for Stainless Steel 304 Alloy

In the present research the effect of corrosion on buckling behavior of 304 stainless steel with increasing of compressive dynamic loads was studied. There are two types of the columns, long columns and intermediate columns were used. For compression test, there are 24 columns specimens were used in the dynamic axis, 12 columns tests were carried out with increasing in the dynamic axis of compressive load, while for the corrosion test was performed by using 12 specimens were buried for two months under the ground before tested them. The allowable deflection in lateral axis is 1% in the length of column. When the deflection in lateral axis reaches 1% and does not increase more than it, and when removing the applied load, the column will return back to the normal state. This is defined critical buckling of columns. To calculate the original deflection. The digital gauge was employed at the distance about 0.7 for the column length at the fixed end of column. has alarm system was used to define critical buckling and to avoid the failure of the specimen and installed at the distance equal to 0.7 of the column length from fixed end. The empirical results showed that the effect of negatively corrosion on mechanical properties of alloys with 2.53% reduction of ultimate tensile strength comparing with non corroded specimens, in the other hand the corrosion will reduce the critical buckling load by 6% for two months. The experimental results comparing with the theoretical results obtained by Perry Robertson and Euler. Johnson with the results analyzed by ANASYS17. The results of this work are agreed with Perry-Robertson and Euler- Johnson by a safety factor about (1, 3) and 3 respectively while the results of ANASYS showed that agreement with the calculated and measured values by safety factor about (2).

Stress corrosion cracking of biodegradable Mg-4Zn alloy in simulated body fluid at different strain rates – A fractographic investigation

Degradable magnesium based implants are predisposed to failure by stress corrosion cracking (SCC) when subject to tensile loads in the human body. Slow strain rate (SSR) tests are used in SCC analysis and the applied strain rate is a critical factor to determine if the material failed by stress corrosion or mechanical overload. In this paper, the SCC susceptibility of Mg-4Zn alloy in simulated body fluid (SBF) is investigated at different strain rates. It was found that elongation to failure (ε) and ultimate tensile strength (UTS) decreased by 80% and 58% respectively when extension rate in SBF decreased from 3.6 × 10−4 s−1 to 3.6 × 10−6 s−1. When the Mg-4Zn alloy is strained in SBF, multiple surface cracks appear on the gauge, initiated at the corrosion pits that induce mechanical overload and failure at higher strain rates. As the strain rate decreases, the increased contact time between the surface and SBF results in hydrogen embrittlement, micro crack formation and progressive transgranular failure that is evident in the fractography. The reduction in UTS and elongation even at the highest strain rate tested indicate that the critical strain rate for stress corrosion cracking of Mg-4Zn alloy in simulated body fluid could be as high as 3.6 × 10−4 s−1.