Increase In Strength Of Material Research Articles

Ratcheting assessment of additively manufactured SS316 alloys at elevated temperatures within the dynamic strain aging domain

The present study has evaluated the accumulation of plastic strain in additively manufactured (AM) stainless steel 316 samples undergoing asymmetric loading cycles at elevated temperature range where the dynamic strain aging (DSA) phenomenon occurred. The ratcheting response of AM steel samples were assessed through the use of the combined isotropic-kinematic hardening framework. The dynamic strain aging was introduced into the dynamic recovery term of the Ahmadzadeh-Varvani (A-V) kinematic hardening rule by an exponential function ψ(p, T). This function enabled the hardening framework to evaluate the ratcheting of AM steel samples at operating temperatures within the DSA domain. The DSA temperature range for AM SS316 samples fell between 700 K to 1140 K. Within this temperature domain, the interaction between solute atoms and dislocations led to an increase in material strength and suppressed the magnitude of ratcheting over the loading cycles. The influence of DSA on the backstress evolution and the yield surfaces translated in the deviatoric stress space and their subsequent influence on the ratcheting of samples using the A-V model were further discussed. The predicted ratcheting curves at the DSA temperature domain were found in close agreement with those of measured values.

Simplified formulas for calculating bearing capacities of standing seam metal roof systems under uniformly distributed downward and upward loads

Finite Element (FE) models of standing seam metal roof systems (SSMRSs) are established and verified by experimental results. A comprehensive parametric study on the bearing capacities of SSMRSs under uniformly distributed loads through FE simulations encompassing 281 SSMRSs is conducted. Simplified formulas for calculating the bearing capacities of SSMRSs under uniformly distributed loads are proposed as functions of fundamental parameters, including roof panel thickness, roof panel width, purlin spacing, material strength, friction coefficient, and support head width. These simplified formulas avoid the necessity for calculating the effective section during the verification of bending failure and avoid the necessity for wind uplift experiments during the verification of connection failure of the SSMRSs in conventional building codes and guidelines. The results show that for per 0.1 mm increase in roof panel thickness, the ultimate bearing capacities under downward and upward loads increase by about 14.03 % and 19.88 %; for per 100 mm increase in roof panel width, they decrease by about 27.14 % and 36.45 %; for per 200 mm increase in purlin spacing, they decrease by about 12.82 % and 5.01 %; for per 20 MPa increase in material strength, they increase by about 11.40 % and 2.24 %; for per 0.1 increase in friction coefficient, they increase by about 3.16 % and 9.01 %. Future studies can focus on the ultimate bearing capacities of SSMRSs under non-uniform loads with temporal and spatial fluctuation.

Experimental study on the cushioning energy absorption characteristics of polymer materials resistant to seawater erosion in seismic damping layers

AbstractPolymer materials exhibit vibration damping properties, yet scant research exists on their applicability to submarine tunnels. This study investigates the dynamic characteristics of Polymer Materials Resistant to Seawater Erosion (hereafter referred to as PMRSE) under varying conditions of density, confining pressure, strain rate, and erosion duration through dynamic triaxial tests. The results reveal an increase in material strength with a rise in density; enhanced strength and ductility with increasing confining pressure; and augmented strength and yield stress in correspondence with heightened strain rates. As confining pressure ascends, the equivalent damping ratio of PMRSE gradually diminishes. SEM and EDS indicate a porous structure for PMRSE, with a molded surface skin formed post‐manufacturing to thwart seawater erosion. The strain energy storage and energy absorption evaluation of PMRSE demonstrate its excellence as an energy‐absorbing material. Eventually, employing a numerical simulation model for a specific submarine tunnel reveals that the presence of a damping layer absorbs seismic energy and enhances the stress conditions of the secondary lining. PMRSE manifests as a strain‐rate sensitive material unaffected by seawater corrosion, which exhibits deformation characteristics of low yield strength and long yield stage. Accordingly, PMRSE proves suitable for vibration damping in submarine tunnels.

Effect of hybrid reinforcements on the curing kinetics and mechanical properties of light‐cured polymer composites

AbstractLight‐cured polymer composites incorporating particle reinforcements have been adopted for a wide range of engineering applications. Nevertheless, micro‐filled composites exhibit insufficient strength despite good abrasion resistance. Conversely, nano‐filled counterparts possess enhanced strength but easily generate particle agglomeration. Hybrid filling has therefore been utilized in previous studies to combine the advantages of different components, but conclusive results have not been obtained. Within this study, the effects of hybrid filling on the strengthening mechanism and curing kinetics of light‐cured polymer composites were investigated by multi‐scale mechanical tests, in‐situ near‐infrared spectroscopy, scanning electron microscope, and finite element simulations. It was found that hybrid filling led to an average increase in Young's modulus by ~3.94%, the hardness by ~5.81%, the tensile strength by ~10.44%, and the degree of conversion by ~2.54% compared to micro‐filling at the same filler content. Besides, hybrid filling showed more reduced particle agglomeration compared to nano‐scale filling. Finite element analysis revealed that hybrid filling effectively enhanced the load‐bearing capacity of the matrix. Overall, the experimental results unveil a mechanism of particle reinforcement that can be extrapolated to various particle‐filled polymers across different length scales. These findings provide a versatile manufacturing technique for composites with heightened mechanical reinforcement and are expected to guide the application in the field of photo‐polymeric materials.Highlights Light‐cured polymer composites incorporating hybrid silica particles were prepared. The strengthening mechanism was investigated by multi‐scale mechanical tests. Hybrid filling could lead to an increase in material strength compared to micro‐filling. Hybrid filling exhibited reduced particle agglomeration in comparison to nano‐filling.

Atomic Reconstruction of Au Thin Films through Interfacial Strains.

Interfaces play a critical thermodynamic role in the existence of multilayer systems. Due to their utility in bridging energetic and compositional differences between distinct species, the formation of interfaces inherently creates internal strain in the bulk due to the reorganization needed to accommodate such a change. We report the effect of scaling interfacial stress by deposition of different adlayers on a host thin metal film. Intrinsic property differences between host and deposited metal atoms result in varying degree of composition and energy gradient within the interface. Interfacial stress can increase defects in the host leading to (i) energy dissipation and reorganization to minimize surface energy, and (ii) increased material strength. We infer that dissipation of interfacial stress induces defect migration, hence bulk and surface atomic reconstruction as captured by the surface roughness and grain size reduction coupled with a concomitant increase in material strength.

An Optimized 3D Printer by Enhancing Material Properties and Surface Finish of PLA Through Modifications

This research investigates the optimization of 3D printer settings to enhance the mechanical properties of polylactic acid (PLA) printed parts. A fundamental aspect of this study involves the design and development of a 3D printer capable of accommodating varied printing parameters. The parameters under consideration include extruder temperature, layer height, print speed, and infill density. Through experimentation, the tensile strength and the bending strength of PLA material are systematically evaluated against these printing parameters. The results unveil significant correlations between printing parameters and mechanical properties. It is observed that increasing the extruder temperature up to 220°C increases the material strength, beyond which a decline is evident due to overextrusion and material degradation. Conversely, increasing the layer height leads to a reduction in strength, attributed to diminished layer adhesion and structural integrity. Moreover, decreasing print speed is found to enhance strength at the expense of increased print time, suggesting a trade‐off between efficiency and mechanical performance. Furthermore, the study demonstrates that augmenting infill density contributes to a notable increase in material strength, underscoring the importance of internal reinforcement in enhancing structural integrity. These findings provide valuable insights into the optimization of 3D printing processes for PLA materials, offering guidelines for achieving superior mechanical properties through precise calibration of printing parameters.

Mechanical Properties of Titanium Grade 1 After Laser Shock Wave Treatment

Abstract In the presented work the impact of a laser shock wave on the mechanical properties of a Titanium Grade 1 was investigated. Based on a series of experimental studies related to the impact of the laser shock wave on the tested material, the impact of the given treatment on the structure and mechanical properties was assessed. The influence of the environment on the distribution of plasma temperature and pressure in the material during the implementation of the laser shock wave was analyzed. The effect of the laser treatment on the structure and micromechanical properties was initially estimated on the basis of the analysis of experimental results in the form of static strength test of samples after laser treatment. A slight increase in material strength was detected with a minimal decrease in ductility. In order to comprehensively understand the observed phenomenon, a number of fractographic tests were performed, especially the analysis of the porosity of the fracture surfaces. A decrease in the porosity of the material after impact laser treatment was observed as a result of local plastic deformation.

Improvement Mechanical Properties of Epoxy Composite Reinforced with Sisal, Ramie and Carbon Fibers

In this paper, justification of mechanical characteristics is carried out to determine the ability of bio-composites to become structural composite bicycle frames capable of achieving strengths of more than 300 [MPa]. Sisal fiber is a natural fiber that is widely used as a composite fiber and is easy to cultivate. The fiber is believed to originate from Central and South America. Nearly 4.5 million tons of sisal fiber are produced annually worldwide, according to FAO. In building structural materials, in addition to structural strength, it is hoped that the material will also have good ductility. For this reason, the assembled bio-composite material consists of carbon fiber, ramie fiber, sisal fiber. The fiber is then mixed with hard epoxy resin, soft epoxy and aluminum particles 9 µm which are mixed until smooth and even. The significant increase in material strength is obtained from the strength of carbon fiber. Another thing is that the ductility of the material is obtained due to sisal and ramie which are bound by a mixture of epoxy resins. Because the quality of plant products is very dependent on the agricultural process, this study, the residual material was taken from the Subang (Indonesie) area and the ramie fiber was obtained from the Bandung market. Because agricultural cultivation in Indonesia still emphasizes the use of chemicals, basically this also has an impact on plant bio elements. However, research using local materials was still able to obtain strength reaching ~480 MPa, so it is still good. In this research, the tensile test was carried out 3 times so that it is known that the fiber taken from a rope has the greatest tensile strength which reaches around 480 MPa.

The precise control of end flare with residual stresses of UHSS thin-walled component in roll forming process

ABSTRACT To control precisely end flare of UHSS thin-walled component, FEA (finite element analysis) model of multi-pass RF (roll forming) process is established. Numerical simulations with developed FEA model considered Young's modulus variation and RF tests are conducted to explain the origin of end flare with residual stresses. It's found that the overlap of bending moment caused by residual longitudinal stress and twisting moment caused by residual shear stress in transversal-longitudinal direction leads to opening deformation in front end and back end for hat channel steel. End flare will decrease with the increase of flange length and increase with the increase of material strength. The effect of forming parameters on end flare is analysed that end flare can be reduced with UDT-type (USTB-Durable T) method, constant-arc-length method and appropriate forming parameters. The findings are applied to control end flare of hat channel steel in actual RF process to meet high-precision requirements.

Rolling‐assisted direct energy deposited Inconel 718: Microstructural evolution and mechanical properties after optimized heat treatment

Post-heat treatment is a necessary and important step for additive-manufactured products to relieve residual stress and to further improve mechanical performance. In this work, the heat treatment strategy for Inconel 718 superalloy fabricated by rolling-assisted laser-directed energy deposition (L-DED) has been designed and systematically investigated for the first time. The results show that the designed homogenization heat treatment at 1080°C for 10 min can effectively dissolve most of the detrimental Lave phases existing in the rolling-assisted L-DED samples. Meanwhile, it results in a homogenous grain structure through static recrystallization, while maintaining a similar prior-refined grain size of ∼8 µm. On this basis, a high number density of γ’’ and γ’ precipitates appear in the microstructure after applying a subsequent double-aging heat treatment. The optimized microstructure through such effective post-heat treatment designed in this work has led to a significant increase in material strength at both the room and elevated temperatures while maintaining good ductility.

Assessment of arresting performance of foamed concrete arrestors via the coupled discrete element and virtual prototype simulations

Engineered material arresting system (EMAS) is a foamed concrete arrestor that can arrest aircraft overrunning the runway. Identification of the arresting effect of foamed concrete materials on overrunning aircraft is crucial for optimizing EMAS. By coupling the Discrete Element Method (DEM) and the Virtual Prototype Method (VPM), the EMAS crushing process and the aircraft dynamics are simulated simultaneously. The material properties of different foamed concrete were firstly determined via experiments, and then adopted as input for DEM of EMAS. Subsequently, the VPM of A320 aircraft with various overrun speeds was established. The rationality of the DEM-VPM model was verified by the field test result. The sensitivity analysis on the arresting processes reveals that a 67% increase in EMAS thickness and a 102% increase in material strength can enhance the arresting performance by 96% and 11.5%, respectively. However, freeze–thaw has negative effect. In addition, higher overrun speeds of the aircraft can cause greater acceleration and drag forces, and thereby magnify the risk of damage to the aircraft.

The effect of differential mineral shrinkage on crack formation and network geometry

Rock, concrete, and other engineered materials are often composed of several minerals that change volumetrically in response to variations in the moisture content of the local environment. Such differential shrinkage is caused by varying shrinkage rates between mineral compositions during dehydration. Using both 3D X-ray imaging of geo-architected samples and peridynamic (PD) numerical simulations, we show that the spatial distribution of the clay affects the crack network geometry with distributed clay particles yielding the most complex crack networks and percent damage (99.56%), along with a 60% reduction in material strength. We also demonstrate that crack formation, growth, coalescence, and distribution during dehydration, are controlled by the differential shrinkage rates between a highly shrinkable clay and a homogeneous mortar matrix. Sensitivity tests performed with the PD models show a clay shrinkage parameter of 0.4 yields considerable damage, and reductions in the parameter can result in a significant reduction in fracturing and an increase in material strength. Additionally, isolated clay inclusions induced localized fracturing predominantly due to debonding between the clay and matrix. These insights indicate differential shrinkage is a source of potential failure in natural and engineered barriers used to sequester anthropogenic waste.

Effect of blank quenching on shear spinning forming precision of 2219 aluminum alloy complex thin-walled components

The quenching-spinning (Q-S) process, i.e., shear spinning after blank quenching, has been increasingly utilized to form 2219 aluminum alloy complex thin-walled components. However, the changes in material property, shape and stress of the blanks after quenching will affect the spinning forming precision. In this study, the rules and mechanisms of these effects are investigated based on a combined finite element (FE) model including blank quenching and component spinning process. The results indicate that the increase of material strength and the existence of distortion of the quenched blank lead to a notable increase in the non-uniformity of the circumferential compressive stress in the spinning area and the increase of the flange swing height during spinning. These changes result in an increase in the wall thickness and component-mandrel gap of the components. The quenching residual stress has little effect on wall thickness and roundness but can noticeably reduce the component-mandrel gap. This is because that the existence of quenching residual stress of the blank can lead to the decrease of the maximum circumferential compressive stress of the workpiece in spinning and an obvious drop in the maximum compressive stress after reaching the stress peak. Quenching distortion is the main factor affecting the roundness. Moreover, the optimized installation way of the blank for spinning is obtained.

Research on Hanger Force and Main Arch Stability of Long-Span Concrete-Filled Steel Tube Arch Bridge

In recent years, the construction of a CFST arch bridge has developed rapidly; however, as a kind of structural system dominated by compression, with the increase of material strength and span, the stability of the main arch of the CFST arch bridge has become more and more important. In this paper, the finite element method is used to analyze the hanger force and the main arch stability of the long-span CFST arch bridge. Combined with the Shenzhen Rainbow Bridge project, the axial force of the hanger, the internal force, and stability of the main arch of the arch bridge are studied. In the establishment of the finite element model, considering the actual operation of the arch bridge, the model simulates the interaction between steel pipe and concrete, it studies the large deformation of CFST arch bridges, and the stress distribution and overall stability of the arch bridge are analyzed. The results show that the main deformation of the CFST arch bridge is the vertical displacement of the deck, and the axial force of most members of the upper arch ribs is greater than that of the lower arch ribs. The axial force and bending moment of the lower arch rib near the arch foot are larger, and the compressive stress of the arch foot is greater than that of other positions. The axial force of the suspender of the arch bridge is the largest at both ends of the hanger and the middle hanger, and the axial force of the other hanger is close to each other, and the axial force changes little under the same case. The buckling modes of the arch are mainly the lateral buckling or flexural buckling of the arch rib outside the plane, which indicates that the vertical stiffness of the arch bridge structure is larger than that of the transverse stiffness. The research results make the load-bearing mechanism of the CFST arch bridge more clear and also provide a certain reference for the design and construction of the CFST arch bridge.

Numerical Analysis on Post-Fire Resistance of High-Strength Circular CFST Stub Column in Axial Compression

Concrete-filled steel tubular (CFST) structures using high-strength materials have been increasingly used in civil engineering due to their exceptional mechanical performance. A comprehensive numerical analysis was performed in this study, where a finite element model was established for a CFST stub column using high-strength materials with consideration of fire and load combinations. The influence of critical parameters to the resistance in axial compression were analyzed based on the verified model, including the fire exposure time, the axial load level, the confinement factor, etc. The results showed that the residual resistance of a high-strength circular CFST (HCFST) column in axial compression decreased with the increase of axial load level and fire exposure time, while it increased with the increase of material strength.

Accuracy of Two-Dimensional Limit Equilibrium Methods in Predicting Stability of Homogenous Road-Cut Slopes

Although limit equilibrium methods are widely used by engineers and scientists in predicting the stability of homogenous slopes, their use has been demonstrated to present significant errors due to the violation of kinematic and static admissibility. The concern is often voiced regarding the accuracy of limit equilibrium methods (LEMs) solutions in predicting the stability of homogenous slopes. There are no exact limit equilibrium solutions or charts available that could be used to check the LEMs solutions. The present study has used the rigorous upper and lower bounds solutions of limit analysis based on finite element formulations of the bound theorems to benchmark and develop an accuracy classification chart of limit equilibrium methods in predicting the stability of the homogenous slope. Six case studies of homogenous road-cut slopes that vary with material properties were used and the effect of the increase in material strength with depth was considered. The results of LEMs and limit analysis solutions have shown that Janbu simplified limit equilibrium solutions are closely related to those of rigorous upper bound solutions with an accuracy error ranging from 1 to 7% in various slope materials. Meanwhile, the Corp of Engineer 2 limit equilibrium solutions were found to overestimate among other methods, with an accuracy error ranging from 12 to 17% in various cases. Based on the results of the study an accuracy error classification chart of LEMs is developed.

On the strength–ductility trade-off in thin blast-loaded steel plates with and without initial defects — An experimental study

An increase in material strength is commonly associated with better protection in blast-resistant design. However, higher material strength comes at the cost of reduced ductility, and it is still not clear how this trade-off affects the load carrying capacity of blast-loaded structures. This work presents an experimental investigation of the strength–ductility trade-off on the dynamic response of thin steel plates subjected to blast-like loading conditions. Two different plate materials were applied for this purpose; one dual-phase, medium-strength, high-hardening steel, and one martensitic, high-strength, low-hardening steel. Seven plate geometries with various pre-formed defects were tested for both materials, triggering distinctly different deformation and fracture modes in the plates. In total, six different blast intensities were applied, and all tests were recorded using two high-speed cameras synchronized with pressure measurements. 3D-DIC measurements were used to track the mid-point displacement and deformation profile of the target plates until fracture. For plates without defects, the high-strength, low-hardening steel resulted in the smallest deflections for a given load. However, for plates with pre-formed defects, the medium-strength, high-hardening steel showed a superior resistance to fracture. The geometry of the pre-formed defects was found to significantly influence the global deformation, the resistance against crack propagation, and the fracture mode.

Equal channel angular sheet extrusion (ECASE) produces twinning heterogeneity in commercially pure titanium

Commercially pure grade 2 titanium in sheet form was processed by equal channel angular sheet extrusion (ECASE) up to two passes at room temperature. The ECASE process generated a heterogeneous state of deformation, mainly affecting the sheet metal edges´ vicinity. The deformation heterogeneity gave rise to notable microstructural changes throughout the sheet thickness with high densities of twins located around 600 μm from the sheet edges. At the same time, the middle zone was kept free of twins. The highest twin density generated with the ECASE process corresponds mostly to tension twins of type 101¯2101¯1 oriented towards the extrusion direction. The heterogeneous structure produced a material strength increase of 200 MPa, maintaining a uniform deformation zone of 10%. The good strength-ductility combination was related to a heterogeneous distribution of geometrically necessary dislocations (GNDs) between the hardest and softest areas. The edge areas presented greater GNDs of type ⟨a⟩ on the twins' exterior than in their interior while in the middle zone, the highest GND densities grouped around triple points and grain boundaries. It was found that the grains with the most significant capacity to nucleate twins and store GNDs were those with the c-axis of the crystals parallel to the normal direction (ND). According to the Hall-Petch relationship, the strength improvement of the heterogeneous material comes from the grain size reduction mainly due to twins induced by deformation around the edge areas.

Cyclic loading test and nonlinear analysis on composite frame consisting of steel reinforced recycled concrete columns and steel beams

A two-span and three-story of the frame specimen with a scale of 1:2.5 was tested and investigated under cyclic loading to study the seismic behavior on the composite frame consisting of steel reinforced recycled concrete columns and steel beams. After observing the loading process and failure modes, the mechanical properties of composite frame, such as the load–displacement hysteretic curves, skeleton curves, bearing capacity, interstory displacement angles, ductility, energy dissipation and stiffness degradation, were analysed in detail. On this basis, a finite element model of the composite frame which considered the constitutive properties of recycled concrete was established. The deformation diagram, stress nephogram and calculated skeleton curves of composite frame were obtained, and a nonlinear parameter analysis was also conducted. The experimental and numerical analysis results all show that the plastic hinges appeared at the end of steel beams firstly and then formed at the end of columns, which is a typical plastic hinge failure of frame. The hysteretic curves of frame are shuttle-shaped and full, and the descending section of the skeleton curves and stiffness degradation curves is relatively gentle. The average ductility coefficient, equivalent viscous damping coefficient and ultimate interstory displacement angle of frame are 3.205, 0.303 and 0.04, respectively. Therefore, the composite frame has good deformation, energy dissipation capacity and collapse resistance. The results of the nonlinear parameter analysis on the frame also exhibit that increasing the strength of steel products or recycled concrete is beneficial to the horizontal bearing capacity and lateral stiffness of frame. The maximum increase in the bearing capacity of frame can be 21.5% when the profile steel strength is increased from Q235 to Q390 and the recycled concrete strength is maintained at C40 within the parameters analysed, but the increase in material strength is unfavourable to the deformation capacity of frame. Increasing the axial compression ratio of columns in the frame obviously weakens the lateral displacement ductility of frame, which makes the frame unsafe under an earthquake. In addition, the bearing capacity and stiffness of frame increases with the increase in the linear stiffness of beams and columns. The research conclusions can provide a reference for the engineering application of this type of composite frame.

Concentration Dependent Effects of Green Inhibitors on Gravimetric Indices of Corrosion Linked Metal Integrity

The use of plant phytochemicals as anti-corrosion agents is gaining widespread acceptance. This study was designed to evaluate the concentration dependent effects of green inhibitors from Pennisetum purpureum (elephant grass) Mangifera indica (mango leaves) and Heveabrasiliensis (rubber leaves) on some gravimetric indicators of corrosion linked metal stability. The material strength, weight loss, corrosion rate of the metal coupons and the inhibition efficiency of the green inhibitors were determined after 3 days. Our findings revealed a slight increase (p=0.05) in material strength (MS) of Pennisetum purpureum inhibitor treated - iron and steel at 100% inhibitor relative to their controls (minus Pennisetum purpureum -iron and steel coupons) and also relative to the (+Mangifera indica inhibitor and + Heveabrasiliensis -treated iron and steel coupons at 50% concentration. The material strength for P. purpureum-treated aluminium was slightly increased (p>0.05). There was also a slight decrease (p>0.05) in the weight loss of P. purpureum exposed iron coupon at a 100% inhibitor when compared to the controls, 50% P. purpureum exposed iron coupon and at 50 and 100% H. brasiliensis and M. indica-treated iron coupon in 15% acid medium. Pre-treatment of test metals with the combined green inhibitors at 50 and 100% concentration caused a significant (p≤0.05) decreases in weight loss and increases in material strength of all three test metals when compared to their respective inhibitor-free controls, and when treatment was done with a single green inhibitor. There was a slight decrease in the corrosion rate of iron, aluminium and steel coupons in acid medium treated with 50% P. purpureum inhibitor when compared to the same parameter of other green inhibitors evaluated in this study, albeit, the reduction was not significant (p>0.05). There was a further decreases (p≤0.05) in the corrosion rate of iron and steel when the combined green inhibitors at 100% concentration(+All green inhibitors (PAGI) at 100%) were used relative to when treatment was done using individual green inhibitors separately. The inhibition efficiency of the combined green inhibitors at 50% concentration on aluminium, iron and steel was 86% 57% and 60% respectively. While the treatment of the same coupons with combined inhibitors (+PAGI at100% concentration) increased the inhibition efficiency to 88% 75% and 74% for aluminium, iron and steel respectively. Overall, the study revealed the possible anti-corrosion effects of the extracts of H. brasiliensis, P. purpureum and M. indica on aluminium, iron and steel coupons and the synergism in anti-corrosion characteristics of these green inhibitors when combined. This study establishes the anticorrosion effects of H. brasiliensis, P. purpureum and M. indica extracts.