Surface Severe Plastic Deformation Research Articles

Surface nanoprecipitation induced by severe plastic deformation in the Fe49.3Co23Ni23C0.85Mn1Si2.85 biphasic multicomponent alloy

Precipitation strengthening plays a vital role in enhancing the mechanical properties of metallic materials, typically achieved through heat treatment. However, deformation-induced precipitation (DIP) in multicomponent alloys (MAs) without the assistance of annealing is rarely reported, owing to their inherent high entropy and sluggish diffusion effects. This work reveals the significant formation of nanoscale and microscale precipitates in dual-phase Fe49.3Co23Ni23C0.85Mn1Si2.85 MA triggered by surface severe plastic deformation (SSPD) through industrial shot blasting. The SSPD process leads to the formation of ultrafine gradient structures comprising nanocrystalline and submicron-crystalline zones. Submicron SiO2 precipitates emerge at the interfaces of both these zones, while various Mn5Si3 and Si nanoparticles precipitate within the nanocrystalline zone. This phenomenon can be ascribed to the high density of generated substructures, the accelerated diffusion of atoms, and the reduction in solid solubility limits in the SPD-driven non-equilibrium state.

The strength and ductility mechanism of gradient fine grains prepared by surface severe plastic deformation

The gradient fine grains on low-carbon steel surface were produced via ultrasonic impact treatment, which led to excellent combination of high strength and ductility. Results showed that the grain size had a gradient increasing from 120 nm at top surface to 5–8μm at the matrix. In the gradient fine grain region, the grain boundary misorientation is in the range of 2–15°. Compared with original microstructure, the surface gradient fine grains can achieve a higher work hardening rate. A digital image correlation(DIC) technology was employed to analyze variations in strain during the tensile deformation. It is demonstrated that the surface gradient distribution of grain size can reduce the stress concentration, resulting in higher ability for uniform deformation. Such a capability is attributed to the decreased dislocation density and Schimid factor due to gradient fine grains distribution. Compared with the original microstructure, a number of dislocation walls (or cells, or tangles) can hinder the movement of dislocations. In addition, the surface gradient fine grains have faster recovery and proliferation of mobile dislocation density, which can lead to higher work-hardening ability. As a result, the surface gradient fine grains can attain a combination of excellent strength and ductility.

Enhancement of the Microstructure and Fatigue Crack Growth Performance of Additive Manufactured Titanium Alloy Parts by Laser-Assisted Ultrasonic Vibration Processing

AbstractPost-processing techniques can efficiently improve the surface quality, address microstructural defects, and optimize mechanical properties in additively manufactured parts. Surface severe plastic deformation processes such as ultrasonic nanocrystal surface modification (UNSM) integrated with localized laser heating were explored to enhance the surface properties, microstructure as well as the fatigue crack growth properties (FCG) in both directions of built. We successfully induced greater plasticity flow and achieved beneficial refinement of the surface grain structure by precisely controlling the heat and impact energies during surface treatment process. The LA-UNSM process, with the parameters utilized in this study considerably decreased the FCG rates of treated samples, when compared to samples without surface treatment. Improved fatigue crack growth properties along vertical and horizontal orientations after the post-process treatment were attributed to the induced-microstructural changes, improved surface quality, induced compressive residual stresses through gradient structure deformation layer that was prepared on the surface of the material. The fractographic analysis revealed that the cracks mostly originated from the pores in the as-produced state. This observation shows a clear correlation between the surface treatment performed and a substantial improvement in fatigue crack growth resistance.

Influence of Severe Surface Plastic Deformation Induced by Shot Peening on Microstructure and Corrosion Resistance of fine grained 316 L stainless steel

The influence of a severe shot peening (SSP) treatment in corrosion resistance of AISI 316 L austenitic stainless steel was studied by different electrochemical measurements in 3.5% NaCl solution. SSP promoted the formation of ultrafine grains in the upper layer. The formation of strain induced martensite appears to be facilitated by twinning due to the induced severe plastic deformation. SSP treatment with subsequent low temperature annealing (350ºC) improved corrosion resistance. The distinction of corrosion resistance is attributed to the different mechanical and microstructural features caused by severe plastic deformation. The best properties and stability of passive film were corroborated from various electrochemical techniques: potentiodynamic polarization, potentiostatic polarization and electrochemical impedance spectroscopy.

Modeling of the fatigue behavior of functionally graded materials: Study of the residual stresses induced by surface severe plastic deformation

AbstractA new finite elements approach has been used to model the evolution of residual stresses during cyclic loading in functionally graded 316 L stainless steel, obtained by surface severe plastic deformation. The affected layer modeling was divided in two stages: the compressive residual stress state initialization and the update of the mechanical properties characteristic of the gradient microstructure determined from local characterization. The capacity of the model to simulate both the strain‐ and stress‐controlled fatigue behavior was evaluated, and a good consistency between the numerical and experimental results was obtained. Numerical residual stress fields were compared to the experimental measurements, and a very good agreement was observed. A mean error of approximately 65 MPa over all the compared data was measured. Especially, the relaxed and inverted residual stress gradient after the different testing conditions were nicely retrieved, indicating the capabilities of the newly proposed model.

High Temperature Deformation of Harmonic Structure Designed CrMnFeCoNi High Entropy Alloy

The Harmonic Structure (HS) is a recently introduced concept that paves the way for engineering metallic materials to achieve superior mechanical performance. They consist of soft, coarse-grained regions surrounded in three dimensions by an interconnected network of hard, ultra-fine grained regions. In addition, from a structural materials point of view, high entropy alloys have attracted attention due to their unique mechanical properties. In the present study, the HS design was applied to a high entropy CrMnFeCoNi alloy (also called "Cantor alloy"). The HS-designed Cantor alloy was successfully fabricated by mechanical milling, which is one of the surface severe plastic deformation processes, and the subsequent sintering process. The mechanical properties of these HS and homogeneous (Homo) Cantor alloy compacts were investigated by high-temperature compression tests in the temperature range of room temperature (RT) and 1173K, under initial strain rates of 0.01 s-1, 0.001 s-1, and 0.0001 s-1. The stress-strain curves of the HS compacts showed a large initial increase in stress and then a rapid decrease with strain, while that of the Homo compact showed a gentle increase and a gradual decrease. EBSD observation of the deformed compacts revealed that the HS compacts were probably deformed not only by dynamic recrystallization, but also by grain boundary sliding during deformation. The strain rate sensitivity value m of the HS compacts was 0.541 (true strain: 0.2) at 1173 K. In other words, the HS compacts exhibited pseudo-superplastic deformation at these temperatures.

Crystallographic Textures of Al and Al-Mg Alloy Formed by Shot-Peening

Shot-peening (SP) is one of the severe surface plastic deformation (SSPD) processing techniques. Due to large plastic strain by the SP, the SP for metallic materials forms crystallographic texture on the peened surface. Since the crystallographic texture formed by the SP depends on the dislocation slip, it can be expected that this texture is affected by stacking fault energy (SFE) of the materials. However, effects of the SFE on the crystallographic texture formed on the peened surface by the SP is not clear. In this study, crystallographic textures of pure Al (higher SFE) and Al-10 mass%Mg alloy (lower SFE) formed by the SP are investigated. When the pure Al is SPed, {001}+{111} double fiber texture with the <001> and <111> directions parallel to the plane normal direction of the peened surface is obtained. On the other hand, in the case of Al-10 mass%Mg alloy with the SFE close to the pure Cu, {110} fiber texture is formed as well as the pure Cu. Therefore, it is found that the crystallographic texture formed by the SP is influenced by the SFE.

A Study on Surface Hardening and Wear Resistance of AISI 52100 Steel by Ultrasonic Nanocrystal Surface Modification and Electrolytic Plasma Surface Modification Technologies.

In this study, a surface hardening of AISI 52100 bearing steel was performed by ultrasonic nanocrystal surface modification (UNSM), and electrolytic-plasma thermo-cyclic surface modification (EPSM), and their effects on the wear resistance were investigated. To evaluate the impact of these treatments on the wear resistance, the friction tests under dry conditions were conducted using a ball-on-disk tribometer in accordance with ASTM G99. The microstructure of the samples before and after treatment was characterized by scanning electron microscopy. The micro-hardness with respect to the depth from the top surface was measured using a Vickers micro-hardness tester. Microstructural observations showed that EPSM treatment led to the formation of residual austenite in the surface layer, while UNSM treatment led to the formation of a surface severe plastic deformation layer on the surface of the samples. The increase in the micro-hardness of the treated layer was confirmed after UNSM at room temperature and after EPSM at different cycles. The highest increase in wear resistance was observed for the specimen treated by UNSM treatment at 700 °C and five cycles of EPSM treatment. In addition, the wear volume, which has correlation with the friction coefficient and hardness, was determined.

Achieving ultrahigh fretting fatigue endurance in TB8 titanium alloy with hierarchical structure via triggering nanocomposite and phase transformation

Extraordinary fretting fatigue endurance is critical for engineering structures prone to contact with expected long service lifetimes. Here, we propose a strategy to achieve ultrahigh fretting fatigue endurance in titanium alloy. A special hierarchical structure, i.e. gradient amorphous-nanocrystalline grain/coarse grain, was designed in a TB8 titanium alloy via surface severe plastic deformation, which forms an nanocomposite structure comprising of amorphous-nanocrystalline and nano-lamellae and β to α phase transformation upon repeated fretting wear. The nanocomposite surface and phase transformation suppress cracks initiation and propagation, resulting in the high fretting fatigue life that was 30.2-times higher than that of the original TB8 titanium alloy via triggering an exceptional fretting fatigue phenomenon where damage-crack initiate towards the interior of non-fretting contact zone. This study provides a new insight into improving the fretting fatigue endurance of titanium alloys.

Corrosion property of Al alloys subjected to surface severe plastic deformation: a review

Purpose This study aims to discuss the influences of surface severe plastic deformation (S2PD) on the electrochemical corrosion, pitting corrosion, intergranular corrosion, stress corrosion cracking of aluminum (Al) alloys and attempt to correlate the microstructural/compositional changes with the performances. Design/methodology/approach This study provides a novel gradient design of structure/composition caused by S2PD for the purpose of enhancing Al alloys’ corrosion resistance. Findings S2PD has a significant effect on corrosion behavior of Al alloys through tuning the grain size, residual stress, composition, grain boundary phase and second phase particle distribution. Originality/value Although Al alloys are known to form a protective Al2O3 film, corrosion is a major challenge for the longevity of Al structures across numerous industries, especially for the infrastructures made of high-strength Al alloys. Traditional strategies of improving corrosion resistance of Al alloys heavily relied on alloying and coatings. In this review, gradient design of structure/composition caused by S2PD provides a novel strategy for corrosion protection of Al alloys, especially in the enhancement of localized corrosion resistance.

Surface Severe Plastic Deformation for Improved Mechanical/Corrosion Properties and Further Applications in the Bio-Medical and Hydrogen Sectors

Various techniques enabling surface severe plastic deformation (SSPD) have been developed or optimised over the past years. This manuscript presents a broad overview of recent developments in the field of SSPD and its application that take advantages of having a deformed gradient surface with both (i) higher strength and (ii) an improved "reactivity". First, the principle and technological advantages/disadvantages of several SSPD technologies, involving either guided or non-directional mechanical impacts, are recalled. Then, after a short recall on the nature of the structure the modified surface formed under SSPD, the effects of the processing parameters and temperature of deformation on the surface roughness and subsurface microstructure modifications are illustrated with a particular emphasis on the surface mechanical attrition treatment (SMAT) and ultrasonic shot peening (USP) techniques deriving from the traditional pre-strain shot peening. The effect of these surface and sub-surface modifications on the mechanical properties, and in particular the fatigue response, are recalled with a special emphasis on the surface integrity and potential over shot peening. Then, the manuscript concentrates on the effect of the surface enhanced diffusion of chemical species induced by the presence of structural defects to modify the corrosion behaviour and enhance the potential assisted SSPD + thermo-chemically “duplex” treatments. In these cases, in addition to induce grain refinement and dislocations, the importance of controlling some potential surface contamination is stressed. Finally, the manuscript terminates by illustrating some new research studies on potential applications for the challenges in the hydrogen sector for its solid-state storage and the protection of mechanical infrastructures as well as for bio-medical applications with biocompatible Ti-based alloys and biodegradable Mg-based ones.

A mini-review of surface severe plastic deformation methods and their effects on steel and stainless steel

Surface severe plastic deformation is an important technology for the preparation of bulk ultrafine grain or even nanocrystalline materials. Based on the technical achievements made in the field of surface severe plastic deformation at home and abroad, this article presents the basic principles of various kinds of surface severe plastic deformation techniques in detail. In addition, the effects of surface severe plastic deformation on the microstructure and mechanical properties of steel and stainless steel are reported. The current status of research on the effects of surface severe plastic deformation on fatigue properties and the tribological and biological properties of steel and stainless steel are summarized. The problems of the current surface severe plastic deformation technology for steel and stainless steel are pointed out, and the future development trend is foreseen.

Mechanical Properties of Metallic Materials Processed by Surface Severe Plastic Deformation

This paper gives an overview about some mechanical properties of materials processed by surface severe plastic deformation (SSPD) techniques. SSPD processed materials are classified in terms of their characteristics, and some main generated parameters that determine the output properties of materials are presented. The influences of SSPD on mechanical properties of materials are then reviewed. Furthermore, the roles played by some important parameters such as gradient microstructure, nanostructured layer, compressive residual stress (CRS) and surface integrity are highlighted by discussing their contributions to the mechanical properties of materials. Finally, some conclusions are drawn and possible prospects for future research are underlined.

Thermal oxidation of Ti-6Al-4V ELI with an ultrafine-grained surface at 500 °C: Oxidation kinetics, oxide characterization and corrosion performance

The oxidation behavior of Ti6Al4V ELI alloy subjected to surface severe plastic deformation (SSPDed) is compared to its solution annealed (SAed) counterpart in Ar + 20 % O2 atmosphere at 500 °C. Moreover, the corrosion performance of oxidized SAed and SSPDed samples is examined in the Ringer solution. The significantly increased presence of high-diffusivity paths, specifically dislocations and grain boundaries (GBs), on the surface of SSPDed sample facilitates the diffusion of oxygen anions and scale-forming elements toward the oxidation front. The SSPDed sample shows a superior oxidation performance due to the rapid formation of a three-layered oxide scale (consisting of an outer Al-rich, an intermediate Ti-rich, and an inner Al-rich oxide layer) on its surface. In contrast to the SAed sample, the SSPDed displays inner and outer Al-rich oxide layers that are more uniform and virtually continuous. The study proposes a physical model that attributes the improved high temperature oxidation and enhanced corrosion resistance of oxidized SSPDed samples to the latter Al-rich inner oxide layer.

Effect of the residual stress induced by surface severe plastic deformation on the tensile behavior of an aluminum alloy

Surface severe plastic deformation (SSPD) improves the mechanical behaviors of materials by generating non-uniform, heterogeneous microstructures on their surfaces. SSPD enhances the mechanical properties of the material, such as resistance to fatigue and yield strength. Herein, a decrease in the yield strength after SSPD, which is contrary to the findings of previous studies that report increased yield strengths, was considered. The main cause of this phenomenon was the internal tensile residual stress, which was inevitably induced by the surface compressive residual stress during SSPD. The inherent residual stress after SSPD was measured and applied in a tensile study of a real Al alloy to verify the phenomenon. Finally, the effects of the residual stress on the tensile mechanical properties were analyzed via analytical and numerical methods. Moreover, the transient behavior in the early stage was determined based on residual stress.

Improving embrittlement in the Ti-Al-C MAX phase system: A composite approach for surface severe plastic deformation

Ti2AlC and Ti3AlC2 belong to an interesting family of layered compounds called MAX phases. A composite approach is tested here to improve the intrinsic brittle behaviour of such compounds. To this end, a bulk MAX compound and a MAX/TiAl2 composite have been deformed under surface severe plastic deformation (SSPD) by surface mechanical attrition treatment (SMAT). Grain delamination and grain decohesion occurred to a depth of 100 µm below the surface for the bulk compound. Resulting cracks and grain pullouts were witnessed by a decrease in the surface and sub-surface hardness. Comparatively, the presence of intergranular TiAl2 effectively prevented such failure for the composite. Thus, the SSPD of this cohesive composite created a surface hardening (+60%) gradient extending down to a depth of 250 µm. Witness marks of plasticity were revealed in both the MAX and TiAl2 phases.

Improving fatigue life of additively repaired Ti-6Al-4V subjected to laser-assisted ultrasonic nanocrystal surface modification

Ultrasonic nanocrystal surface modification (UNSM) combined with localized laser heating (LA) were implemented to enhance the surface fatigue life of additively repaired Ti-6Al-4V alloy parts in this study. The effect of induced surface severe plastic deformation on microstructure development and grain refinement is analyzed. The results showed that surface metallurgical defects, hardness, residual stress, and roughness were significantly improved after LA-UNSM treatment. As a result of the improved surface textures and higher grain refinement, the fatigue life of the LA-UNSM treated samples was an order of magnitude longer. Surface free of pores and displaying a healthy topography provides evidence.

The Correlation between Surface Integrity and Operating Behaviour of Slide Burnished Components—A Review and Prospects

This review paper analyses and summarises the results found while studying the slide burnishing (SB) of metal components refracted through a prism during the surface engineering (SE) process, over the period of January 2019 to January 2023. According to the classification of SE processes defined in the article, SB as a technique in the scope of SE that belongs to the group of static surface cold working (SCW) processes, based on severe surface plastic deformation, and is realised under the condition of sliding friction contact with the treated surface. When the deforming element is natural or artificial diamond, SB is known as diamond burnishing (DB). SB is especially suited for axes, shafts, and holes with circular cross-sections but can also be implemented on flat-face and complex surfaces. SB is eco-friendly and a very economical method for producing mirror-like surface finishes on a wide range of ferrous and non-ferrous machined surfaces, but it can also be realised as a hardening and mixed process with the aim of significantly increasing the fatigue strength and wear resistance of the treated components. Based on a literature review of the results of the theory and practice of SB, an analysis on different criteria was carried out, and graphic visualizations of the statistical results were made. Additionally, the results were analysed using the integrated approach of SE to study the correlations between the apexes of the triangle: SB—surface integrity (SI)—operational behaviour (OB). On this basis, relevant conclusions were drawn, and promising directions for future investigations of SB were outlined.

Deposition characterization of high-manganese (13Mn) steel built via directed energy deposition and its wear behavior

High-manganese steel (HMS) has high work-hardening and impact toughness as well as excellent wear resistance. In this study, directed energy deposition (DED) was employed to deposit HMS onto the surface of Inconel 718. The deposition characteristics were analyzed according to laser power and powder feed rate. From the results, the lowest amount of pores and lack of fusion were observed when the laser power was 1050 W and the powder feed rate was 4 g/min. In the first layer of the deposited HMS, the Laves phase was formed due to fusion with Inconel 718, while the hardness rapidly decreased to 250 HV because of the low hardness of the Fe–Ni phase. A wear test was conducted according to different loads and RPMs using the ball-on-disc method, with the results indicating that a higher load led to a lower wear rate. When the wear load was high, the surface hardness increased after the wear test, and surface severe plastic deformation (SSPD) thickened. Such phenomena occurred because the grains near the surface underwent refinement and the dislocation density increased as the load increased. An oxide layer was generated on the surface at 300 RPM, but no oxide layer was formed at 100 RPM. As an oxide layer was not formed, the wear rate was the highest at 100 RPM due to direct contact between the ball and matrix. This study demonstrates the industrial applicability of surface coating using HMS as a powder for maximizing wear resistance.

Effects of Heat Treatment and Severe Surface Plastic Deformation on Mechanical Characteristics, Fatigue, and Wear of Cu-10Al-5Fe Bronze.

Aluminium bronzes are widely used in various industries because of their unique properties, a combination of high strength, wear resistance, and corrosion resistance in aggressive environments, including seawater. In this study, the subject of comprehensive experimental research was Cu-10Al-5Fe iron-aluminium bronze (IAB) with β-transformation, received in the form of hot-rolled bars. The effects of different heat treatments (HT) and severe surface plastic deformation (SPD), conducted by diamond burnishing (DB) on the microstructure, surface integrity (SI), mechanical properties, low- and mega-cycle fatigue strength, and dry sliding wear resistance, were determined. Based on quantitative indicators, the applied heat treatments in combination with severe SPD were compared. Thus, the integral efficiency of the heat treatments was evaluated, and the heat treatments were correlated with the resulting properties and operational behaviour of Cu-10Al-5Fe IAB. For example, if the component is designed for rotational bending conditions, the combination of quenching at 920 °C in water, subsequent tempering at 300 °C for three hours, and DB provides maximum fatigue strength in both low-cycle and mega-cycle fatigue applications.