Macrohardness Tests Research Articles

Correlated high throughput nanoindentation mapping and microstructural characterization of wire and arc additively manufactured 2205 duplex stainless steel

Duplex stainless steels (DSS) in wire and arc additive manufacturing (WAAM) have attracted significant research attention due to their mechanical properties and corrosion resistance. This study uses conventional and nanomechanical testing methods to compare the mechanical and microstructural behaviors at macroscopic and microscopic length scales. Macro hardness (HV10) testing yielded 259 and 249 in low and high heat input (HI) samples, respectively, while ferrite content averaged 52.7 and 48.5%. However, these results fail to provide conclusive insight into the potential influence of microstructural variations at the macroscopic level, likely due to the composite response of the material. To overcome this limitation, the mechanical response of the DSS samples is assessed at the grain level via high throughput nanoindentation mapping with image processing to track the location of each indent. This approach enabled differentiating the indents landing on ferrite and austenite phases as well as those landing on the interfaces. The results showed that the austenite phase had higher hardness (4.30 and 4.35 GPa) than the ferrite phase (3.89 GPa and 4.03 GPa) for high and low HI samples, respectively. The observed differences in hardness between the phases can be attributed to higher nitrogen content in the austenitic phase.

Developing austenitic high-manganese high-carbon steels for biodegradable stent applications: Microstructural and mechanical studies

Fully degradable stents that temporarily support healing tissue can solve potential long-term complications associated with permanent implants. In this study, we investigate austenitic high-manganese high-carbon steels as promising candidates for such biodegradable stent applications. The microstructural characteristics and mechanical properties of the Fe–Mn–C steels were systematically analysed to assess their suitability for this purpose. A series of four austenitic Fe–Mn–C steels with varying manganese (15 and 30 wt%) and carbon (0.6–1.0 wt%) content were processed by vacuum induction casting, annealing and hot forging. Microstructural analysis was performed, and the hot forged materials were further evaluated using ultrasound, macro hardness, and (stopped) quasi-static tensile tests to assess stent-related parameters. In contrast to the as-cast state, the hot forged steels exhibited high chemical homogeneity, as was found by energy-dispersive X-ray spectroscopy (EDXS). Electron backscatter diffraction (EBSD) revealed comparability between the four steels regarding their annealing twin fractions and grain size distributions. An austenitic microstructure was revealed for all modifications by transmission X-ray diffraction (XRD), except Fe–15Mn–0.6C, which displayed a minor ε–martensite fraction. Reducing manganese from 30 to 15 wt% resulted in favourable effects, including a higher Young's modulus, lowered offset yield strength, and an increased ultimate tensile strength due to larger strain hardening while preserving a high total elongation. However, reducing the carbon content to 0.6 wt% diminished the mechanical performance due to reduced solid solution strengthening and the ε–martensite formation. Among the investigated steels, the novel Fe–15Mn–0.8C alloy exhibited the most attractive combination of the studied properties for potential stent applications.

Hybridization Effect on Interlaminar Bond Strength, Flexural Properties, and Hardness of Carbon-Flax Fiber Thermoplastic Bio-Composites.

Hybridizing carbon-fiber-reinforced polymers with natural fibers could be a solution to prevent delamination and improve the out-of-plane properties of laminated composites. Delamination is one of the initial damage modes in composite laminates, attributed to relatively poor interlaminar mechanical properties, e.g., low interlaminar strength and fracture toughness. This study examined the interlaminar bond strength, flexural properties, and hardness of carbon/flax/polyamide hybrid bio-composites using peel adhesion, three-point bending, and macro-hardness tests, respectively. In this regard, interlayer hybrid laminates were produced with a sandwich fiber hybrid mode, using woven carbon fiber plies (C) as the outer layers and woven flax fiber plies (F) as the inner ones (CFFC) in combination with a bio-based thermoplastic polyamide 11 matrix. In addition, non-hybrid carbon and flax fiber composites with the same matrix were produced as reference laminates to investigate the hybridization effects. The results revealed the advantages of hybridization in terms of flexural properties, including a 212% higher modulus and a 265% higher strength compared to pure flax composites and a 34% higher failure strain compared to pure carbon composites. Additionally, the hybrid composites exhibited a positive hybridization effect in terms of peeling strength, demonstrating a 27% improvement compared to the pure carbon composites. These results provide valuable insights into the mechanical performance of woven carbon-flax hybrid bio-composites, suggesting potential applications in the automotive and construction industries.

Microstructure, Nano-, and Macro-Indentation Characterization of AISI 302 Steel After High-Temperatures Aging

The structural and mechanical studies of the AISI 302 steel aim to design a correct heat treatment in order to optimize its mechanical properties. In this study, we investigated the influence of temperature and time of aging on the structural and mechanical characteristics of the AISI 302 steel. The steel was aged at temperatures of 1100°C and 1200°C and for times ranging from 0 to 6000 minutes. The structural and mechanical characterization techniques used were the metallurgical microscope, nanoindentation technique, and macro-hardness test. At the microstructural level, an increase in the time or temperature of the aging contributed to an increase in the austenite grains size of AISI 302 steel. This microstructural change led to a decrease in the nanohardness and a drop in the macro-hardness between the unaged and aged conditions of AISI 302 steel.

YÜKSEK ENERJİLİ ÖĞÜTME İLE ÜRETİLEN Al2O3 TAKVİYELİ CU KOMPOZİTLERDE PARÇACIK BOYUTUNUN ETKİSİ

Production of copper (Cu) composites with a reinforced Cu matrix using mechanical alloying with Aluminum oxide (Al2O3) particles of different sizes was achieved using high-energy ball milling procedure. The initial materials consisted of inert gas-atomized spherical electrolytic Cu powders containing 0.5 wt. % commercial Al2O3 powders, with particle sizes ranging from 10 µm to 1 µm. Cu powders with different particle sizes of Al2O3 were high-energy ball milled at 500 rpm for 3 hours to attain a consistent distribution of Al2O3 throughout in the Cu matrix. The powders that were high-energy ball milled were then subjected to cold-pressing at 500 MPa and isothermally sintered for 1.5 hours at 880°C in an Ar atmosphere. The fabricated copper composite materials were characterized using X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDXS), density and macrohardness tests. The wear properties and mechanism were investigated through tribological pin-on-disc experiments, which revealed that the reinforcing effect was more significant when finely dispersed Al2O3 particles were combined into the Cu matrix compared to coarse Al2O3 particles.

Microstructure, macro-, and nano-hardness assessment of AISI 302 steel aged at 1000°C

Changes in the microstructure of the AISI 302 steel must be analyzed in order to optimize its mechanical performance. In this paper, we studied the thermal aging behavior of the AISI 302 steel. The aging treatments of the steel were carried out at a fixed temperature of 1000°C and for durations between 0 and 6000 minutes. A metallographic microscope was used to see changes in the AISI 302 steel microstructure. In addition, the steel was mechanically characterized using the nano-indentation technique and macro-hardness tests. At the temperature investigated, the aging time increase caused a microstructure composed of large austenitic grains and a small area of grain boundaries per unit volume. For the mechanical characterization, the nano-indentation responses also showed a decrease in the nano-hardness and plasticity of the austenite as the aging time increased. The steel macro-hardness decreased significantly by incrementing the aging time.

Textural development, martensite lath formation and mechanical properties variation of a super strength AISI4340 steel due to austenitization and tempering temperature changes

In this investigation, the textural development, as well as martensite lath formation on the microstructural changes and mechanical properties variation of a super strength AISI 4340 was studied under different austenitization and tempering conditions. To study the influence of tempering temperature, austenitization temperature of 900 °C was followed by tempering in the range of 200–425 °C on the sheet samples. As well, to investigate the effect of austenitization temperature, austenitization temperature of 850–1200 °C was followed by rapid quenching and tempering at 200 °C. Microstructural investigations were conducted using optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) that was equipped with the electron backscattered (EBSD) as well as energy dispersive spectroscopy (EDS) detectors, X-Ray diffraction (XRD), and transmission electron microscopy (TEM). In addition, mechanical properties were evaluated using tensile testing, macro-hardness testing, and Charpy impact testing. Results showed that increasing austenitization temperature up to 950 °C increased ductility which was followed by a sharp drop as the austenitization temperature increased thereafter. Also, it was found that increasing the austenitization temperature from 850 to 1200 °C decreased yield strength (Y.S), and ultimate tensile strength (U.T.S) for about 24%, 26%, respectively. It reduced impact energy by about 35%. Such reductions were related to the increased mean diameter of the prior austenite grain size from 2 μm for the former temperature to 110 μm in the latest temperature. EBSD analysis showed that the steel texture was mostly randomized at high austenitization temperature. (100) pole figure analysis showed that Cube ({100} 〈001〉) and Copper ({112} 〈111〉) components were developed during the optimized heat treatment of 900 °C followed by tempering at 200 °C. PF analysis also indicated that the texture intensity was weakened at lower austenitization temperatures. The presence of the Copper component at the very low austenitization temperature could explain the low ductility of this scenario. Orientation distribution function (ODF) analysis showed that the Cube component was dominant, and the Copper component severely weakened, during the optimum austenitization temperature, which would explain the optimum mechanical properties combinations, particularly ductility. Finally, the mentioned optimized route provided Y.S of 1720 MPa, U.T.S of 1900 MPa, El% of 11%, and Impact energy of 44 J, which confirmed the development of super-strength steel.

An Approach to Assessing S960QL Steel Welded Joints Using EBW and GMAW

In recent years, ultra-high-strength structural (UHSS) steel in quenched and tempered (Q+T) conditions, for example, S960QL has been found in wider application areas such as structures, cranes, and trucks due to its extraordinary material properties and acceptable weldability. The motivation of the study is to investigate the unique capabilities of electron beam welding (EBW) compared to conventional gas metal arc welding (GMAW) for a deep, narrow weld with a small heat-affected zone (HAZ) and minimum thermal distortion of the welded joint without significantly affecting the mechanical properties. In this study, S960QL base material (BM) specimens with a thickness of 15 mm were butt-welded without filler material at a welding speed of 10 mm/s using the high-vacuum (2 × 10−4 mbar) EBW process. Microstructural characteristics were analyzed using an optical microscope (OM), a scanning electron microscope (SEM), fractography, and an electron backscatter diffraction (EBSD) analysis. The macro hardness, tensile strength, and instrumented Charpy-V impact test were performed to evaluate the mechanical properties. Further, the results of these tests of the EBW joints were compared with the GMAW joints of the same steel grade and thickness. Higher hardness is observed in the fusion zone (FZ) and the HAZ compared to the BM but under the limit of qualifying the hardness value (450 HV10) of Q+T steels according to the ISO 15614-11 specifications. The tensile strength of the EBW-welded joint (1044 MPa) reached the level of the BM as the specimens fractured in the BM. The FZ microstructure consists of fine dendritic martensite and the HAZ predominantly consists of martensite. Instrumented impact testing was performed on Charpy-V specimens at −40 °C, which showed the brittle behavior of both the FZ and HAZ but to a significantly lower extent compared to GMAW. The measured average impact toughness of the BM is 162 J and the average impact toughness value of the HAZ and FZ are 45 ± 11 J and 44 ± 20 J, respectively.

Macro-hardness and corrosion behavior of silicon carbide or boron carbide reinforced AA5052 MMC

Metal Matrix Composites (MMCs) enhance the mechanical and tribological properties according to the composition of the particulate reinforcement of Silicon Carbide (SiC) or Boron Carbide (B4C) and AA5052 aluminum alloy matrix. The MMC samples were fabricated by stir casting method of the liquid processing route. The same weight percentages (5 wt. %) and same particle size (63μm) of both SiC and B4C particulates are used to develop two different MMC samples. The hardness and corrosion tests were conducted to estimate the enhanced properties of the fabricated composites. The macro-hardness test and the immersion corrosion test were carried out by using a Vickers hardness tester at an applied load of 5kgf in accordance with ASTM E92 and a 3.5% NaCl solution in accordance with ASTM G31, respectively. With the help of optical microscopy, the corroded surfaces were analyzed. The results obtained from the investigation show that AA5052/B4C MMC gives better hardness and AA5052/SiC MMC shows higher corrosion rate compared to the other two samples.

Microhardness model based on geometrically necessary dislocations for heterogeneous material

Lamellar cast irons are known as heterogeneous materials. Their overall hardness is determined by the microhardness of their microstructure contents. This study pertains to extend the indentation size effect (ISE) analyses to these heterogeneous materials. Additionally to macrohardness tests, Vickers microindentation tests were carried out on two cast irons with fully pearlitic matrix. Tensile models for pearlitic steel with both Tabor's law and Taylor's model were introduced in the ISE analyses. Microhardness expressions of the pearlitic phase within these irons were thus obtained. The obtained expressions indicate that the tensile model and the concept of geometrically necessary dislocations (GNDs) can be used to predict the ISE of the pearlitic matrix. For this pearlitic phase, it is shown that the summation of the stresses, associated with the GNDs and SSDs, is more adequate than to consider only one work-hardening stress generated by the two types of dislocations density in the ISE study.

Effect of vanadium content on the microstructure and wear behavior of Fe(13-)VxB7 (x = 0–5) based hard surface alloy layers

In this study, Fe (13- x ) V x B 7 (x = 0, 1, 2, 3 and 5) based hard surface alloy layers were formed on SAE 1020 steel substrate surface by tungsten inert gas (TIG) welding method. The effects of vanadium addition on microstructure, hardness and wear rate in this coating layer were investigated using optical microscope, SEM (EDS), X-ray diffractometer, hardness and wear tests. As a result of microstructure studies and phase analysis, it was determined that the structures of alloy layers consist of α-(Fe,V), α-(Fe,V) + (Fe,V) 2 B eutectic, and (V,Fe)B phases. As a result of the macrohardness tests, it was found that the hardness of the alloy layers varied between 42.3 ± 1.7–57.2 ± 5.1 HRC. Moreover, the microhardness of iron and vanadium borides formed in the coating layers was found to be between 1901 ± 127–3082 ± 299 HV 0.01 , respectively. As a result of the wear tests, it was observed that as the amount of vanadium added to the hard surface alloy layer increased, the wear rates decreased for all applied loads. Morover, Scanning Electron Microscopy (SEM) images of the worn surfaces showed that the wear mechanisms were adhesive, micro-abrasive and oxidative. • Coating on Fe (13- x ) V x B 7 (x = 0, 1, 2, 3 and 5) based hardfacing steel surface with different vanadium content. • The effect of vanadium content on the microstructure of Fe-V-B based coatings. • Determination of the mechanical properties of the hard surface alloy layer depending on the vanadium content.

Development of hardening treatments for 58Ni39Ti-3Hf alloy system as compared to baseline 60NiTi

58Ni39Ti-3Hf alloy system has been proposed as an alternative for superelastic 60NiTi used in load-bearing applications. This research was focused on the development of heat treatment procedures leading to 58Ni39Ti-3Hf parts with maximum possible hardness values. Meanwhile, the relations existing between the heat treatment – microstructure – hardness of 58Ni39Ti-3Hf as compared to baseline 60NiTi were also investigated. These were done by applying the solution and consequent aging treatments on the studied alloy systems at different temperatures and for different times. The microstructure and hardness of the treated samples were, in the next step, analyzed by applying electron probe micro-analyzer (EPMA), energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and macro hardness testing techniques. It was understood that applying solution treatments at temperatures above about 1000 °C resulted in the relatively full dissolution of Ni-rich phases such as Ni3Ti and Ni3Ti2, existing in the microstructure of as-received parts, in the NiTi matrix of 60NiTi. On the other hand, for 58Ni39Ti-3Hf, temperatures above about 900 °C appeared to be adequate to solve these Ni-rich phases in the NiTi matrix. Applying aging treatments had either no significant effect on the hardness of solution treated 60NiTi samples (~58 HRC) or reduced their values; after coarsening of Ni4Ti3 particles formed in NiTi matrix and their transformation to Ni3Ti and Ni3Ti2 phases. On the other hand, some of the applied aging treatments could increase the hardness values of the solution treated 58Ni39Ti-3Hf alloys (~54 HRC). The maximum value of hardness (~59 HRC) for the aged 58Ni39Ti-3Hf parts was obtained for the ones treated at 500 °C for just 0.25 h. This level of obtained hardness is comparable to that of solution treated 60NiTi. A delayed precipitation of Ni3Ti and/or Ni3Ti2 phases was noted in aged 58Ni39Ti-3Hf alloy system as compared to 60NiTi.

Enhancment of the corrosion resistance of copper metal by laser surface treatment

In this work, the copper metal was treated using Nd:YAG laser with energy 1Joul to enhance corrosion resistance and improve surface properties. The copper metal has many applications in industry as well as water, oil and gas pipes. The same conditions, (laser power density, scan speed, distance between paths, medium gas-air) were applied in the laser surface treatment, After laser treatment, the samples microstructures were investigated using optical microscope (OM) to examine micro structural changes due to laser irradiation. Specimen surfaces were investigated using atomic force microscopy (AFM), X-ray diffraction (XRD), macro hardness, and corrosion test before and after laser treatment to examine the surface properties changes as a result of laser irradiation, and X-ray fluorescence (XRF). Results showed that laser irradiation enhances the corrosion resistance of the metal copper. Corrosion rates as low as 0.550 mpy for laser treated samples were obtained in comparison to 0.699 mpy obtained for the untreated samples. The corrosion protection afforded by laser treatment is attributed mainly to the grain refinement of the top surface layer. This layer is found to consist of nano-scale grains. Higher hardness and lower average roughness due to laser surface treatment.

Promising bending properties of a new as-rolled medium-carbon steel achieved with furnace-cooled bainitic microstructures

The bending properties of a new thermomechanically processed medium-carbon (0.40 wt% C) low-alloy steel, intended for the slurry transportation pipeline application, have been investigated. The studied material was hot-rolled to 10 mm thick strips followed by direct quenching to two different quench-stop temperatures (QST) of 560 °C and 420 °C. The samples were subsequently cooled slowly to room temperature in a furnace, producing two different bainitic microstructures. In general, the final microstructures on the centerline consisted of different bainitic features with yield strengths of a ~700 MPa and ~1200 MPa for QST 560 °C and 420 °C, respectively. To determine the factors affecting bendability, as determined by three-point brake press bending tests, local microstructural features and texture were characterized with transmission and scanning electron-microscoy and macrohardness tests. Detailed quantitative microstructural evaluation of both subsurface and mid-thickness regions revealed that the bainitic sample produced at the higher temperature (QST 560) consisted of almost equal amounts of bainite types B1 and B2, where B1 has bainitic sheaves with a low dislocation density and intralath cementite, and B2 a very dislocation-dense morphology with mainly interlath cementite. In the QST 420 sample, the high dislocation density components B2 bainite and martensite were dominant, although martensite was only present near the strip surfaces. Different post-rolling cooling conditions did not change the general crystallographic theme but resulted in a slight increase in the texture intensity of the QST 420 sample. Neither the concave nor convex subsurface regions showed significant changes in texture after bending. The more favorable distributions of microstructural components and textural component intensities in the QST 560 sample resulted in higher elongation to fracture and work-hardening capacity, resulting a smaller minimum usable punch radius than for the stronger QST 420 sample. Fractographic examination of the cracked surfaces revealed that cracks developed by shear band formation followed by surface roughening, which promoted subsequent void and micro crack nucleation and growth.

γ Decomposition in Fe–Mn–Al–C lightweight steels

In the last few decades the steelmaking industry has been focusing on lightweight steel development and the Fe–Mn–Al–C system has been put under the spotlight. In fact, this quaternary alloy has been shown to be able to lower common steel density by more than 20 wt.%. In addition, these steels may also be suitable for cryogenic applications, corrosion and high-temperature oxidation resistance and wear resistance. Austenite plays an important role in Fe–Mn–Al–C steels because of its possible evolutions. Each configuration derived from γ reaction has its own specific properties and/or drawbacks, which need to be mastered in order to develop valuable products. The aim of this paper is to study the different austenite decomposition reactions at different temperatures for different chemical compositions: the microstructures obtained have been characterized by means of optical and SEM microscopy with the support of Vickers macro-hardness tests, SEM-EDS and phase volume fraction diagrams. Results have made it possible to characterize four different γ transformations. Limiting conditions for triggering each reaction have been established, in terms of the chemical composition driving force, thermal energy input and thermodynamic stability of austenite. Discontinuous precipitation occurred at 600 °C and in a medium Mn, high Al and high C combination. Cellular transformation developed at 800 °C annealing between 9–12% Al. For 1% C spinodal decomposition was triggered at the expense of cellular transformation, as far as austenite stability is influenced by the κ-carbide driving force as well.

Effect of High Entropy Alloy Weight Fraction on Structural Behavior and Hardness of Al-MMC’s

This Paper reports the effect of High Entropy Alloy (HEA) weight fraction on the structural behavior and hardness variation of Aluminum Metal Matrix Composites (MMC’s). The AlFeCuNiMgZn HEA is reinforced to Al MMC’s with varied weight fraction viz., 5%, 10%, 15%, and 20%. The phase constituents of the HEA powders and Al-HEA composite powders were characterized through X Ray Diffraction (XRD) studies. Scanning Electron Microscope (SEM) images of sintered samples were discussed. Macro hardness test was performed employing Rockwell B Scale. Density of the both green and sintered samples tends to increase with increase in HEA weight fraction. Hardness of the samples also follows the similar trend for both green and sintered samples

The Effect of Nitrogen Flow Rate on the Loadbearing Capacity from Nano- to Macro-Hardness of Austenitic Stainless Steels Magnetron Sputtering-Coated with Stainless Steel Films

UNS S31603 stainless steel (SS) substrates were covered by reactive magnetron-sputtering with protective SS coatings of the same steel specification. A mechanical characterization study (through nano-, micro- and macro-hardness tests) of samples obtained under two different sputtering conditions and varying the N2 gas flow rate was carried out. This contribution aimed at appraising the effects of varying the nitrogen flow rate on hardness, elastic modulus, and susceptibility to indentation-induced crack formation of the coated SSs. Nitrogen-free samples displayed body-centered cubic (BCC) films with 9.0-9.4 GPa hardness and 203-206 GPa elastic modulus, while their susceptibility to indentation-induced cracking varied between superior and moderated among the two sets of sputtering conditions studied. Samples alloyed with 4-6 N at-% displayed a predominantly face-centered cubic (FCC) structure, 9.4 GPa hardness, 196-218 GPa elastic modulus, and superior resistance to crack formation. Samples with 11.5-22.0 N at-% were fully composed of the FCC structure, displayed 12.4-15.2 GPa hardness, 188-193 GPa elastic modulus, and moderated resistance to indentation-induced crack formation. Samples with 47.0 N at-% displayed FCC compound nitride structure, for which hardness and elastic modulus were 8.1 GPa and 139 GPa, respectively. These samples displayed low resistance to crack formation.

A novel phase transition behavior during dynamic partitioning and analysis of retained austenite in quenched and partitioned steels

We have studied here the carbon partitioning during continuous cooling at different cooling rates using dilatometer. An interesting phase transition was observed involving multiple stages of transformation during dynamic partitioning and a mechanism was proposed to explain the observations. Two morphologies of nano-sized retained austenite were observed, film-like and block-type. It was proposed that the amount of retained austenite was stable in a certain range of cooling rate. When the cooling rate was between 0.05°C/s and 1°C/s, the carbon partitioning was adequate and ~ 11 to 14% retained austenite was obtained. With increase in cooling rate from 5 and 10°C/s, carbon partitioning was not adequate, which resulted in decrease in film-like austenite. The austenite adjacent to ferrite had two different transformation products, M/A (martensite-austenite island) and twin martensite, based on the degree of carbon transfer from ferrite. However, macro-hardness test showed that cooling rate had little effect on hardness and the hardness was between 398 HV and 407 HV at cooling rate of ~ 0.05 to 10℃/s. Additionally, samples cooled at low cooling rate indicated continuous TRIP effect and excellent combination of high strength 1030MPa and high elongation of ~ 25% was obtained in the plate cooled at 0.1℃/s. On the basis of results, a strategy was proposed to obtain high performance hot rolled Q&P steels. The study confirmed the viability of implementing quenching and partitioning process in the hot rolling production line.

Development of Mild Steel – B4C Surface Composite by Friction Stir Processing

Objectives: Friction Stir Processing (FSP) is being attempted in this study to process the surface layer of mild steel and to explore the possibility of incorporating B4C particle into surface layer of mild steel to form surface composite by means of FSP technique. Methods: FSP with B4C particle was carried out on 5.0 mm mild steel and specimens 250 mm x 100 mm were processed in a single pass. The tool material used was tungsten carbide. Trial runs were carried out at different process parameters and the final parametric windows have been developed for getting the defect free surface. With optimized process parameters sound and defect free surface was made. Mechanical Properties were investigated through microstructure and hardness test. The micrographs and hardness graph have been presented and discussed in this paper. Findings: The Micrographs were taken using optical microscope at different location of the processed zone. There was distinct alteration in size and shape of the grains at different location of the processed area. Temperature in the stir zone is sufficient to convert the base material ferrite into austenite region of phase diagram. Since the recovery is slow in austenite, dynamic recrystallization occurs. The amount of deformation in friction stir processing is very large, therefore the critical condition for discontinuous dynamic recrystallization are met. This leads to very fine austenite grain formation. These fine recrystallized grains of austenite transform back into ferrite when the temperature falls down. Macro hardness test was also done using the Vickers hardness test. It was found that the average hardness has increased to more than three to four times in the processed zone as compared to the parent metal. Applications: Technology developed in this study can be effectively used in several areas like mining, mineral processing, aerospace and railway industry, where surface modification is a need to reduce various losses like wear and corrosion.

Hardness and indentation modulus of resin-treated wood

This study assesses the potential of instrumented macrohardness testing for the fast and convenient characterisation of resin-treated wood. The effect of WPG (weight per cent gain; percentage mass of resin based on dry wood; high, low) and curing conditions (dry, wet) on hardness and indentation modulus of Scots pine (Pinus sylvestris L.) sapwood was investigated for two thermosetting resins, phenol formaldehyde and methylated melamine formaldehyde. Thickness of the treated specimens broadly confirmed the findings of earlier studies that dry curing conditions increase degree of cell wall penetration. Dry curing resulted in equal or lower hardness, but it mostly increased indentation modulus. Hardness improvement seems to depend on the overall reduction of the void volume fraction in the wood, while indentation modulus depends on cell wall modification. Therefore, indentation modulus is expected to show a much better correlation with dimensional stability and durability of resin-treated wood than hardness.