Rockwell Hardness Tester Research Articles

Microstructural characterization of HP50 stainless steel tube from ethylene plant radiant furnace after 4 years of operation

The microstructure of HP50 cast stainless steel tubes for radiant ethylene cracking furnace, which has been in service for four years at about 900 °C, was investigated. Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy, and Rockwell hardness test were used to analyze the material properties. Extensive growth of the primary carbide network and secondary carbide precipitates caused by carburization were observed near the inner wall of the tubes. In contrast, the area near the outer wall showed minimum carbide growth due to decarburization. The quantitative analysis results showed that the fraction of carbide in the inner, mid, and outer areas were 33, 10, and 4% respectively. Hardness test data confirmed this observation and showed increasing hardness in the inner area and decreasing hardness in the mid and outer areas. Carbide-free zone and precipitation of silicon oxide were observed on both the inner and outer walls. Intergranular corrosion due to sensitization and severe carburization occurred on the inner wall.

Laser Processing of Polymers for Surface Energy Control of Biomedical Implants

Poly (etheretherketone) (PEEK) is a high-performance rigid polymer that combines excellent chemical resistance, mechanical strength, and dimensional stability. PEEK is mostly used in the biomedical field for the manufacture of implants. However, the inherently bioinert PEEK surface poses a challenge in terms of adhesion at the implant-tissue interface. Effective enhancement of the adhesive properties of PEEK can be achieved by modifications of surface wettability and free energy. Although many studies investigate the influence of laser parameters on wettability and topography of PEEK, there is scarce information in literature on surface treatment with CO2 laser of neat PEEK. Furthermore, there is no detailed literature report on impact of various laser parameters on the biomechanical properties of PEEK relevant for implants. Therefore, this work focuses on enhancing surface functionality of PEEK through surface energy control. Samples treated at various laser power, fluence, beam pitch and number of passes were characterized with 3D profilometry, Rockwell hardness test, compression tests and contact-angle measurements. Generally, CO2 laser treatment of PEEK did not result in unfavorable changes in its bulk mechanical properties, namely, yield strength and elastic modulus only above the ablation threshold. At a fluence of 14 J/cm2, a significant reduction in hardness (98.03 HRM) was recorded with a single-pass processing. A positive correlation was observed between roughness parameters, groove geometries and laser fluence. More intense surface changes were achieved via ablative mechanism with single-pass processes at a lower total fluence in comparison to double-pass ones. Overall, all increases in roughness resulting from non-ablative processes led to improved wettability.

Mechanical and electrical characterization of aluminium alloy metal matrix composites reinforced with graphite

The principle motivation behind this experiment is to fabricate Aluminium Metal Matrix Composite (AMMC) trying to further develop in its mechanical, and electrical properties. To accomplish this, four compositions were chosen. Al 8011, Al 8011 with 2 % Graphite, Al 8011 with 4 % Graphite and Al 8011 with 6 % Graphite. Among different manufacture methods available for the preparation of AMMC, Stir casting was picked because of its effortlessness, minimal expense and it very well may be utilized for large scale manufacturing. The pre-arranged composites' aftereffects on the Ductile test, Rockwell hardness test, Impact test, wear test, Optical microscope, and Electrical Conductivity test were explored, and test results were compared to Al 8011 specimen. The material's elasticity is higher than that of the unreinforced material, according to the Tensile test. The hardness esteems demonstrate an increase in hardness as the level of built-up particles increases. The wear qualities of the specimen were enhanced with increased reinforcements and the equivalent with electrical conductivity test, according to the tribological concentration. The studies clearly showed that adding graphite to the supported Al composite improves its tribological, mechanical, and electrical properties. The microstructure investigation affirms the uniform scattering of the reinforcement in the matrix. This is accomplished by proper stirring processes.

Investigating the precipitation hardening of 2024 aluminium alloy under different quenching media

This work investigates the effects of different quenching media on the mechanical properties of precipitation-hardenable 2024 Al-Cu Alloy. The heat treatment for the alloy requires a solution treatment at 510–530 °C for 2 h, quenching in water at 60 °C, and artificial aging at 160–190 °C for 2–8 h. This procedure was followed for water, ground oil, and air quenchant. The alloy was casted using sand casting and characterized by an X-Ray fluorescence spectrometer. Tensile testing, Rockwell hardness testing, and metallographic analysis were all carried out. The results show that the Ultimate Tensile Strength for air, water, and oil quenched alloys are 20 MPa, 67 MPa, and 85 MPa respectively. The strain at the Ultimate Tensile Strength and the fracture are [0.017, 0.035], [0.022, 0.023], and [0.046, 0.06] for the air, groundnut oil, and water quenched respectively. The results reveal that the alloy quenched in water is much more ductile than the air and oil quenched samples. The water quenched samples have the highest average hardness value of 96″ compared to 66″ and 70″ for air and groundnut oil quenched respectively.

Evaluation of the effects of soda-lime-silica glass with rice husk ash as an additive on the hardness behavior

Demand for eco-friendly materials increases each year due to their excellent properties, which has proved to contribute to developing a sustainable environment. One of the promising raw materials in producing Glass is rice husk, a waste product from paddy harvesting, containing about 90% of silica. Rice husks are usually burnt in an open area and contribute to severe air pollution problems. In this research, Soda-Lime-Silica Rice Husk Ash (SLRHA) glass which is a new combination of soda-lime silicate (SLS) glass and rice husk ash (RHA), was developed for building glass and window application. The hardness properties of the developed SLS-RHA glass system are presented in this paper. These glasses were investigated to determine the effect of RHA addition on the physical properties of SLS glass. The experimental works using RSM have successfully identified the significant factors and optimized the responses. Based on the Rockwell hardness test, the outcomes demonstrated that the glass sample contained 29.84% weight SLS and 0.06% weight RHA. The result indicated that crack propagation was increased with the increasing addition of RHA, which causes an increase in cracks and voids due to the creation of more debonding.

Influence of Heat-Treatment on Microstructural and Mechanical Characteristic of Steel

The AISI 1045 steel is one of the structural steels widely used in the automotive sector for several key components such as connecting shafts, axles etc. It is also used in petrochemicals and power generation units. In material science and engineering, four interdependent parameters are of paramount importance: process, structure, properties and performance. Among all factors, the microstructure is of utmost importance since it governs the properties at large. For instance, the shape, size and distribution of micro- constituents play a vital role therein. Therefore, the main objective is to investigate the influence of thermal correlation on the material, such as annealing, normalizing, tempering and hardening. This was followed by the characterization utilizing Optical Emission Spectroscopy, Impact Testing and Rockwell Hardness Tester. In addition, the microstructure was also studied using the Optical Microscope with up to 1000x optical zoom. Results suggested an improved toughness and hardness when tempering temperature was reduced. This is attributed to decreased grain sizes of micro-constituents upon such treatment.

Microstructure and Mechanical Properties of Cast and Hot-Rolled Medium-Carbon Steels under Isothermal Heat-Treatment Conditions

In this study, the changes in the microstructure and mechanical properties during isothermal heat treatment of cast steel before and after hot deformation were investigated using medium-carbon steel with low alloy content. The microstructural characteristics of the cast and hot-rolled medium-carbon steel under isothermal heat-treatment conditions were examined using optical microscopy and scanning electron microscopy in conjunction with electron backscatter diffraction. The variation in the mechanical properties was evaluated using Rockwell hardness and tensile tests. After maintaining an austenitizing condition at 1200 °C for 30 min, an isothermal heat treatment was performed in the range 350–500 °C, followed by rapid cooling with water. Both the cast steel and hot-rolled steel did not completely transform into bainitic ferrite during isothermal heat treatment. The partially untransformed microstructure was a mixture of martensite and acicular ferrite. At 500 °C, the prior austenite phase changed to Widmanstätten ferrite and pearlite. At 450 °C, bainitic ferrite and cementite were coarsened by the coalescence of ferrite and subsequent diffusive growth. The mechanical properties increased as the isothermal heat-treatment temperature decreased, and the hardness of the cast steel was generally higher than that of the hot-rolled steel. Hardness and strength showed similar trends, and overall mechanical properties tend to decrease as the isothermal heat-treatment temperature increases, but there are slight differences depending on complex factors such as various phase fractions and grain size.

Experimental Investigation on Mechanical Properties of Part Fabricated by Wire Arc Additive Manufacturing Process

Additive manufacturing process is a method of layer by layer joining of materials to create components from three-dimensional (3D) model data. After their introduction in the automotive sector a decade ago, it has seen a significant rise in research and growth. The Additive manufacturing is classified into different types based upon the energy source use in the fabrication process. In our project, we used self-build CNC machine that runs MACH3 software, as well as the MACH3 controller is used to control the welding torch motion for material addition through three axis movement (X, Y and Z). In the project we used ER70 S-6 weld wire for the fabrication and examined its microstructure and mechanical properties. Different layers of the specimen had different microstructures, according to microstructural studies of the product. Rockwell hardness tester used for testing hardness of the product. According to the observation of the part fabricated components using the Wire Arc Additive Manufacturing process outperformed the mechanical properties of mild steel casting process. The product fabricated by Wire Arc Additive Manufacturing process properties is superior to conventional casting process.

Influence of High Temperature Annealing on Microstructure Evolution of Ni-24Fe-14Cr-8Mo Superalloy

The effect of high temperature annealing on microstructure evolution of Ni-24Fe-14Cr-8Mo alloy was investigated through Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Rockwell Hardness Testing Machine. Three kinds of grain growth patterns were found at different annealing temperatures due to carbides precipitation and dissolution. After a combination of high temperature annealing and aging treatment, the hardness versus time curves performed a parabolic pattern. The highest hardness was achieved under 1070°C/60 minutes treatment, and the desirable annealing time should be 60 minutes to 90 minutes.

Mechanical properties and stress distribution in aluminium 6063 extrudates processed by equal channel angular extrusion technique

ABSTRACT This study investigated the effect of temperature and load on the mechanical properties and stress distribution in ECAE processed Al6063. Samples were extruded at temperatures of 350, 425 and 500 under applied loads of 1000, 1100 and 1200 kN and ram speed of 5 mm/s. Hardness and tensile strength of all the extrudates were measured with Rockwell hardness tester and universal testing machine, respectively. Stress distribution in the extrudates was simulated with qform software under different extended applied loads and temperatures. Experimental results showed that billet temperature influenced tensile strength and hardness more significantly than applied load. The grains in the extrudates also became more refined as billet temperature increased. Simulation results indicated that more uniform stress distribution with lower magnitude was observed in the extrudates with increased billet temperature. The hardness and tensile strength of the extrudates as revealed through the uniform stress distribution were enhanced.

Novel conversion annealing pretreatment for improved deposition of diamond coatings onto WC-Co cemented carbide

To maintain the substrate strength and toughness of WC-Co cemented carbide as well as improve its adhesion with a diamond coating deposited by hot filament chemical vapor deposition (HFCVD), a novel conversion annealing pretreatment was studied. The pretreated substrates, as-nucleated, and as-grown diamond coating specimens were characterized using X-ray diffraction, scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and Rockwell hardness tests. It was found that conversion treatment could effectively convert the Co in the surface layer into intermetallic (Co3W, Co7W) and/or Co-rich compound (M6C, M12C) phases. The conversion layer underwent a re-carburization process during the nucleation stage of HFCVD. The intermetallic phases returned to the γ-Co (W) phase which will be encapsulated by the freshly formed WC layer. This is beneficial for seeding growth and new diamond nuclei formation. However, those Co-rich carbides consumed much carbon atoms to decompose and react to form a lot of free γ-Co phase during the nucleation stage, which promoted severe graphitization at the growth interface during HFCVD, and caused the film to peel off. A high-quality microscale diamond coating with an adhesion of the HF 2–3 level could be deposited onto the conversion layer with only the WC and Co3W phases.

Effect of deep cryogenic treatment on microstructure and properties of M35 high speed steel

The effects of cryogenic treatment on microstructure, hardness, red hardness and wear resistance of M35 high speed steel(HSS) were studied by means of scanning electron microscope, X-ray diffractograph, friction and wear tester and Rockwell hardness tester. The results show that with the increase of tempering temperature, the residual austenite in M35 HSS decreases and the grain size increases gradually. After deep cryogenic treatment (DCT), the grain size of M35 HSS is refined and the wear volume is reduced. DCT at 525°C has the best wear resistance. With the increase of tempering temperature, the hardness of M35 HSS decreases first and then increases, and finally decreases sharply. The Rockwell hardness of M35 HSS at 525 °C is the highest, which is 67.1 HRC. The peak hardness of Rockwell increased by 0.7 HRC and the tempering temperature decreased from 550 °C to 525 °C, which showed good stability of red hardness.

Effect of Cold Forging on Wear Resistance of High Carbon Steel for Dolomite Hammer Mill

Hammer mill machine widely use during the process of material reduction in the dolomite industry. The dolomite stone is crushed to the desired shape by the repeated impact of the hammer or crusher. However, since the dolomite stone is milled inside the grinding machine with the help of crusher, it is still challenging because of variety of problem such as the crusher for dolomite hammer mill needs to be changed frequently and no exact data to predict the time taken for the crusher to start wear and how long the crusher can be used before crusher become to wear. In this study, the authors attempt to investigate the effect of cold forging on the wear resistance of high carbon steel for dolomite hammer mill. Specimens of the high carbon steel were prepared for the purpose of this study as per ASTM D695. Cold forging process was conducted using the smith forging method at targeted 3% cold work. Rockwell hardness tester was used to measure the hardness of the specimen. The prototype of the hammer mill machine was used to measure the wear rate to mimic the working principle of the actual hammer mill machine used in the dolomite mining industry. The microstructural analysis was done using a digital metallurgical microscope. The hardness was found to increase from 28.20 HRA to 29.74 HRA for the high carbon steel after conducting the cold forging process. The cold forging process can help to improve the mechanical properties of the material by improving the strength of the material. Moreover, the wear rate of high carbon steel was found to decrease with an increase in hardness. The cold forging process is found to have a significant effect on the hardness and wear rate of high carbon steel. The result obtained in this study is comparable with the previously reported study.

Effect of Quenching on the Mechanical Properties of Carbon Steel for Hammer Mill

This paper covers the effect of quenching on the mechanical properties of high carbon steel for hammer mill. The main objective of this study is to investigate the mechanical properties and microstructure of high carbon steel before and after heat treatment (i.e., quenching). In this study, the specimens were heated at different level temperature which are 750 °C,800 °C and 900 °C prior to quenching process in water with soaking time of 5 minutes. After the heat treatment of quenching process completed, Rockwell hardness test and tensile test were performed, and the results were collected for both untreated and heat-treated specimens. The fractured surfaces of the specimens were also examined by using metallurgical microscope. It was observed that different level of quenching temperature and untreated specimens gave different mechanical properties. The specimen undergone water quenching recorded the highest hardness and tensile strength as 67.9 HRA and 426.11 MPa, respectively. Besides, the microstructure obtained from untreated specimen provided a good combination of ferrite and pearlite, meanwhile in quenched specimens formation of martensite was observed.

Surface Characteristics of Low Carbon Steel JIS G3101 SS400 after Sandblasting Process by Steel Grit G25

This research aims to study the surface characteristics of low carbon steel JIS G3101 SS400 processed by sandblasting using steel grit G25. The sandblasting process is conducted at a fixed nozzle pressure of 5 bar and pressure angle of 90o, and varying nozzle-to-surface distances at 15, 25, and 30 cm, and blasting durations of 25, 45, and 120 s. Surface characterization is firstly carried out by conducting observation on the surface’s morphology by SEM and chemical composition by EDS. Subsequently, visual inspection and measurement on surface roughness and hardness profile identification by Rockwell and micro-Vickers hardness tests are conducted. A paint thickness test using ASTM D7091 was undertaken to observe the surface characteristics related to the coating process. Based on the result, SEM found valleys, granules, micro-cracks, and grits embedded on the surface. The visual inspection shows the roughness is within the range of Sa2 - Sa3 of ISO 8501 with values are Ra 18.1 and Ra 21.4 µm. The hardened layer exhibits a maximum hardness value of 332 HV and a depth of more than 50 µm by sandblasting parameters of 15 cm distance and 120 s duration. Both roughness and hardness profiles are confirmed, increasing with closer nozzle-to-surface distance and longer blast duration. It is concluded that sandblasting using steel grit G25 is effective in improving the mechanical strength and surface hardness of low carbon steel SS400. These mechanical properties are essential in the paint coating of machinery applications such as pump, tank, ship, and pipeline.

Effect of Ce Content on Properties of Al-Ce-Based Composites by Powder-in-Tube Method

Al-Ce based alloys have gained recent interest and have proven to have excellent strength without heat treatment and high thermal stability. Challenges with the production of Al-Ce samples from elemental powders arise due to the elemental material before alloying being susceptible to rapid oxidation. The methodology for making superconductive wire, powder-in-tube, was used as a consolidate Al and Ce elemental powder, and Al-8 wt % Ce-10 wt % Mg composite powder into bulk nanostructured material. Powder samples are fabricated in an inert controlled atmosphere, then sealed in a tube to avoid oxidation of powders. Therefore, most of the powder is used without much loss. We used 316 stainless-steel tubes as a sheathing material. For Al-xCe wt % (x = 8 to 14) samples of elemental powder, liquid phase sintering was used and for Al-Ce-Mg powder solid-state sintering. Characterization of the bulk consolidated material after sintering, and before and after heat treatment, was made using optical and Scanning Electron Microscope imaging, Energy Dispersive Spectroscopy, Microhardness and Rockwell Hardness test. We demonstrated that microstructure stability in Al-Ce-based specimens can be retained after thermomechanical processing. Densification was achieved and oxidation of powder was avoided in most samples. In addition, we found that Fe and Ni in the sheathing material react with Al in the process, and Ce concentration modifies the reactivity the sheath.

WELDING ANALYSIS OF GRAY CAST IRON ASTM A48 CLASS 40 USING SMAW

The mechanical and physical characteristics of gray cast iron are intricately bound to its application as an essential material in manufacturing various goods. SMAW (Shielded Metal Arc Welding) is the most simple and widely used electric arc welding method. In this work, ASTM A48 gray cast iron Class 40 was joining using the SMAW method with the welding position used was 1G or underhand position. The joining used is the Butt Joint using an open Singel V seam with a current of 120A. The joining of Welding was characterized through dye penetrant and hardness tests. Rockwell hardness tests on base metal and heat affected zone reveal that the heat affected zone has the highest hardness value of 56.5 HRC, while the base metal has the lowest hardness value (41 HRC). Graphite, pearlite, and pearlite were all visible in the microstructure study.

Thermal Kinetics of SiCp Reinforced AA7075 Alloy Composite

The present study evaluates the process activation energy or thermal diffusion activation energy (TDAE) to understand the aging kinetics or transformation kinetics. AA7075–5 Vol.% of SiCp composite were fabricated through stir casting technique. Differential scanning calorimetry (DSC) was carried out at different heating rates to understand the precipitation sequence and evaluate the process activation energy or thermal diffusion activation energy (TDAE) of composite. Rockwell hardness tests investigated the aging behavior of AA7075–5 Vol.% of SiCp composite. Results show incorporation of SiCp in the matrix does not affect the sequences of formation and dissolution of precipitate but affects the kinetics of precipitation growth. The formation of precipitation in the alloy and composite requires an access amount of vacancies; an increase in dislocation density may result in heterogeneous nucleation of precipitation and create free path for the kinetically faster atomic transportation of precipitates. Hence, incorporation of SiC particles in the composite would offer a lot of nucleation sites for precipitate, resulting in lower activation energy to form precipitates and takes less time to reach the maximum hardness. In contrast, the addition of a lesser volume fraction of SiCp also showing accelerated aging phenomena in the composite during the aging process. The hardness profile shows hardness increases 3.86% compared to the base alloy AA7075. High-resolution transmission electron microscope (HRTEM) micrograph of peak age (T6) condition divulges that enormous fine and plate-like ή (MgZn2) precipitates are uniformly distributed in the composite.

Effect of B element on Fe-10Cr-B alloy

In this paper, Fe-10Cr-B alloys with different B content were prepared by the method of liquid phase sintering. Optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), Rockwell hardness tester were used to investigate the influence of B element on the structure, phases and macro-hardness of the Fe-10Cr-B alloys. The results show that the hardness of alloys with different B content gradually increases with the increase of B content in the alloy. When the B content is 2.5 wt.%, the hardness of the alloy reaches the maximum value of 61.8HRC. A further increase in the B content will lead to a decrease in the macroscopic hardness of the alloy sample. The alloy with B content of 2.5wt.% is mainly composed of metal matrix and M23 (C, B)6 boron-carbides. The Cr and B elements are mainly enriched in boron-carbides.

In-process cooling of friction stir extruded joints for increased weld performance via compressed air, water, granulated dry ice, and liquid nitrogen

Joining of aluminum alloy AA6061 to mild steel was achieved using a friction stir extrusion (FSE) method in which processed aluminum was extruded into a preformed steel dovetail groove. These joints were subject to various in-process cooling (IPC) methods via compressed air, water, granulated dry ice, and liquid nitrogen as well as varying weld pitches (WP) via the following rotational and translational (inches per minute, IPM) weld parameters: 1500RPM-3IPM, 1500RPM-2IPM, 1000RPM-3IPM, and 1000RPM-2IPM. Rockwell hardness testing and lap shear tensile testing were then used to evaluate the effectiveness of IPC by comparison to uncooled joints. These tests revealed an increase of 4.1% and 3.1% of hardness performance of the water cooled and dry ice cooled respectively compared to the uncooled weld. Additionally, the average tensile shear joint strength increased at a maximum of 4.5% for water cooled joints, 3.7% for air cooled welds, 3.5% for dry ice cooled welds, and 1.8% for liquid nitrogen cooled welds. The use of various IPC sources also revealed that the higher the WP, the stronger the extrusion joint. Thus, WP (revolution per inch, RPI) in order of descending performance are as follows: 750 RPI, 500 RPI, and 333 RPI. The novelty of this IPC and WP research comes from the investigation on the FSE joints compared to past research that has used butt and lap welds. The introduction of IPC and varying WP improved the strength and hardness of the FSE joints with the water cooling yielding the greatest measured improvement.