Rockwell Method Research Articles

Comparison of characteristics of St3 in a free and annealed state

For the manufacture of field pipelines, low-carbon steel grade St3 is often used. It welds well, almost never hardens, and therefore is very convenient for working in structural elements. Studies of samples from this steel grade were carried out for the initial and heat-treated state by the following methods: study of mechanical properties (tensile test, hardness test); microstructural analysis. At the beginning of research, annealing was carried out in the work to obtain an equilibrium structure. According to the results of the experiment, it was noted that after annealing, the steel structure acquired low strength and hardness with high plasticity. After annealing, tensile tests were carried out on steel samples. Tensile tests of the metal were carried out in order to determine the main indicators of mechanical properties and to compare these properties in the initial and heat-treated state. Hardness measurements were carried out according to the Rockwell method. The microstructure of steel samples was studied using an optical microscope “Metam RV-21-1”, which made it possible to study the microstructure at a magnification of 200 times. It is shown that the structure of steel is ferritic-pearlite. In the initial state, there is a segregation banding and segregation streamer. The structure of the steel under study in the initial state is fine-grained. After annealing, it becomes more homogeneous, and the deformation texture disappears.

Studying the Effect of Tempering Temperature during Heat Treatment on the Corrosion Resistance of 13Mn6 Steel Samples

In the conditions of development of rates of the modern production the role of a heat treatment as a main way of receiving steels with the given structure and mechanical characteristics increases. The details applied on production have to have a long endurance not only at an ambient temperature, but also have high strength characteristics at low and high temperatures. In this regard, special attention is paid to the steel applied to manufacturing of such details. 13Mn6 steel concerns one of them. The definition of an influence of a heat treatment of steel - training at various temperatures, steel 13Mn6 on its rust resistance was the purpose of this work. For achievement of a goal such problems as a research of an influence of the various temperature of annealing of steel 13Mn6 on a value of hardness on Rockwell's method were solved; gravimetric researches after a heat treatment for identification of a temperature schedule of the annealing having the maximum indicators of corrosion were held. It is shown that, after spending vacation hardness of exemplars decreases with an increase in temperature. For assessment of corrosion aggression of the environment on the studied exemplars mass and deep indicators of corrosion were paid off. The maximum corrosion rate is observed when training, and the subsequent annealing at a temperature of 300°C, minimum at a temperature of annealing of 500°C.

Influence of the chemical composition on the hardness of defibrator plate segments

Influence of the chemical composition on the hardness of defibrator plate segments. The paper presents the results of the hardness measurements of the material of defibrator plate segments, in connection with their chemical composition. The investigations of the chemical composition were performed using Energy Dispersive X-ray Spectroscopy (EDS). The hardness was measured using the Rockwell method. The increased number of the alloy components leads to an increase in hardness by approx. 3%, in comparison with the normalized L210H21S cast steel. Changes of the chemical composition and increase in the number of alloy components are ineffective from the viewpoint of the alloy hardness.

Evaluation of the influence of low Mg content on the mechanical and microstructural properties of β titanium alloy

It was investigated in order to better understand the relationship between the low presence of Mg in the Ti–Nb–Sn alloy in its mechanical and microstructural properties by the powder metallurgy technique for biomedical application. The blended powders with the nominal composition of Ti–34Nb–6Sn were obtained by milling at 200 rpm/40 min, compacted at 200 MPa. The sintering were carried out at 900 °C/2 h and at 1110 °C/2 h, followed by furnace cooling. The particle size was characterized by the dynamic image analyzer (DIA). The phases quantification and their microstructure were characterized by an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The porosity was characterized by the Archimedes method and also bi-dimensionally by the Image J software. The mechanical tests were performed by the impulse excitation (Sonelastic ®) technique, in order to evaluate the elastic modulus (E) of the sintered materials and the hardness and resistance by the Rockwell method. The results indicated that the sintering at 1100 °C in the materials with Mg, still had particles of Nb not diffused. The microstructure was basically formed by two phases with the presence of Nb non-diffused in all conditions except at 1100 °C in the system without Mg. The β phase % for systems without and with Mg at 900 °C was approximately 80% and 65%. At 1100 °C, 76% and 78%. The E and hardness were 31 GPa and 226 MPa at 900 °C; 49 GPa and 344 MPa at 1100 °C for materials with Mg. The O and N content increased approximately 1.3 times when adding Mg powder.

Effect of phase dispersivity and grain size on hardness of steel vessels at outlet of rolling-press line

The hot production technology of round vessels made of 50 steel on rolling-press line is studied. It is shown that processing by cooled deforming tool leads to uneven distribution of temperature and phase composition along the height of the vessels metal. Oil quenching did not allow the uniformity of structure and hardness to be formed in the unevenly heated metal of the vessels. The study of the microstructure and its phase components made it possible to establish the reasons for the deviations of the hardness along the height, measured by Rockwell method in the bottom and top parts of vessel about 32 and 24 HRC respectively.

ТЕХНИЧЕСКОЕ СОСТОЯНИЕ И ИЗНОСЫ ЛЕВЫХ НОЖЕЙ СКОРОСТНЫХ ПЛУГОВ СЕРИИ ПСКУ МЕТОДЫ ИХ ТОРМОЖЕНИЯ И УСТРАНЕНИЯ

High-speed plowing forces signifi cant changes in the design of the working elements of the plow. Such changes greatly aff ected the wear pattern and, consequently, called for modifi ed technical processes of restoring and strengthening. The working body design includes a plowshare, the function of which is performed by the left-side knife. The research purpose was to control the technical condition of the above-mentioned parts of the PSKu-series plow; study the geometry, location, and magnitude of wear; and develop restoration and hardening technologies. The residual values of thickness and width were used as the criteria for wear since they infl uence the recovery method. These values were controlled by standard measuring instruments – calipers and height gauges. The hardness measured by the Rockwell method (HRC) was used as a criterion for the mechanical properties of the construction material. Studies have shown that the wear on the working surfaces has a rather complex geometry, which is associated with the specifi cs of the force action of the soil. This defect should be eliminated because the probability of extreme wear in thickness increases when the part rotates. The authors proposed that the wear on the left-side knife should be eliminated by patching with a low-carbon electrode and subsequent hardening with surfacing reinforcement. It has been experimentally established that the wear amounts to about 7 mm in thickness and no more than 8 mm in width for a knife with a 45…54 HRC blade. The wear is caused by a hard-facing layer with a hardness of 73…74 HRC on the backside. High-quality heat treatment ensures an increased resistance of the part to abrasive wear. For left-side knives, it is expedient to apply electrode surfacing with a low-carbon rod and the subsequent hardening by surfacing reinforcement.

ПОВЫШЕНИЕ ИЗНОСОСТОЙКОСТИ РАБОЧИХ ОРГАНОВ СЕЛЬСКОХОЗЯЙСТВЕННЫХ МАШИН МЕТОДОМ ТВЧ С ДОБАВЛЕНИЕМ ПОРОШКА, ПОЛУЧЕННОГО СПОСОБОМ ЭЭД

The development of energy and resource-saving methods and technologies for strengthening and restoring the working bodies of agricultural machinery will increase their abrasive wear resistance and durability by using materials from machine-building waste and reduce the cost by 10-30 percent without reducing operational characteristics. (Research purpose) The research purpose is in increasing the abrasive wear resistance and durability of cultivator legs by surfacing powder materials obtained by electroerosive dispersion from solid alloy waste by high-frequency currents. (Materials and methods) Authors obtained a powder for research on their own experimental installations of the CCP "Nano-Center" of electroerosive dispersion from waste of sintered hard alloys of the T15K6 brand. The microhardness of powders and coatings on microshifts was measured using the PMT-3 device, and the hardness of coatings with the KMT-1 microhardometer was measured using the Rockwell method according to GOST 9013-59. The microwave-40AV installation was used to assess the wear resistance of materials of working bodies of tillage machines. (Results and discussion) In the course of laboratory wear tests the relative wear resistance of samples hardened by high-frequency surfacing currents significantly exceeds the wear resistance of non-hardened samples made OF 65g steel, accepted as the reference standard. (Conclusions) Based on the results of experimental studies, the article proposes a new resource-saving technological process for strengthening the working bodies of agricultural machinery through the use of materials from machine-building waste, which allows increasing the abrasive wear resistance of working bodies by 1.5-2 times due to the use of tungsten-containing materials.

Pendinginan Pengelasan menggunakan Metode SMAW pada Kekerasan Baja Karbon ST3 dengan Media Serbuk Semen Putih dan Beban Rockwell 100kgf

Pengelasan merupakan bagian tak terpisahkan dari pertumbuhan peningkatan industri karena memegang peran utama dalam rekayasa dan reparasi produksi logam.Penelitian ini bertujuan untuk mengetahui pengaruh media pendingin terhadap kekerasan logam las dan logam HAZ (heat Affected Zone) yang diuji kekerasan menggunakan metode Rockwell. Penelitian ini dilakukan pada material baja karbon rendah ST 37 yang dilas menggunakan elektroda E6013 diameter 2,6 mm dengan sambungan tumpul, kemudian diberikan pendinginan menggunakan serbuk semen putih.Logam las yang didinginkan dengan media serbuk semen putih memiliki kekerasan yang lebih keras,karena semen putih mengandung C2S yang sulit terhidrasi dan tidak memilikin sifat panas.Setelah dilakukan pengujian pada beberapa titik maka didapatlah hasil berupa nilai rata-rata dari spesimen raw material adalah 48,3 HRB, pengelasan tanpa media isolator = 42,96 HRB dan HAZ =46,4 HRB.Spesimen yang menggunakan serbuk semen putih = 47,65 HRB dan HAZ = 48,2 HRB.Dilihat dari fenomena tersebut dan semen putih memiliki nilai kekerasan yang lebih rendah dari pada udara, dimana HAZ pada kekerasan nilai pada udara 46,4 HRB dan nilai pada semen putih lebih tinggi yaitu 48,2 HRB.

Investigating the mechanisms of shape distortion of the heat-affected region during electric-arc welding of oilfield pipelines

The article studies the issue of the influence of the most encountered in practice defects of welded joints of a one-piece joint, formed in the process of applying a weld when connecting oilfield pipelines to a joint by electric arc manual welding, on the strength characteristics of a welded joint by scrutinizing the condition of the pipe material close to the heat-affected zone. As a test sample, a butt welded joint with obvious defects was used. The geometric parameters of the welded joint were measured using standard means and the hardness of the heat-affected zone was determined by the Rockwell method in certain areas with justification of the welding process. The reason for softening is established. The change in the geometry of the heat-affected area is due to the accumulation of filler material during its melting on one side of the weld with a decrease in welding speed. Recommendations are given for the prevention of the destruction of welded structures and the occurrence of emergency situations in oilfield pipelines.

Дослідження структури та властивостей зносостійких покриттів отриманих методом наплавлення порошковими електродами на основі системи Fe-Ti-B-C

In this study the main purpose was to provide “in situ” synthesis while flux cored arc welding (FCAW) for obtaining hardfacing with fine structure with uniformly distributed titanium borides and carbides in the Fe-Ti-B-C system. Also, Fe-Ti-Mo-B-C with equimolar content of Me/B4C was researched. Powders electrodes was manufactured with using of pure metal powders to provide “in situ” synthesis. Initial components were powders of Ti, Mo and B4C. It was investigated that the offered harfacings are characterized by high hardness and fine-grained structure. Addition of Ti to Fe-Mo-B-C system leads to elimination of the ferrite-boride eutectics, that exist in Fe-Mo-B-C. Also, the structure of hardfacing of Fe-Ti-Mo-B-C is characterized with absence of defects and pores that exist in case of using Fe-Ti-B-C hardfacing. Analysis was carried out using scanning electron microscopy (SEM) and electron backscatter diffraction (BSD). Hardness was measured by Rockwell method. According to the analysis of literature and experimental researches, a systems of powder electrode materials was manufactured by FCAW method with high content of hard borides and carbides. The obtained value of the hardness of Fe-Ti-B-C system is 67 HRC and for Fe-Ti-Mo-B-C system is 69 HRC.

Physicomechanical Studies of Ancient Ceramics Discovered in Kyrgyzstan

The results of multi-method studies of the physicochemical properties of Bronze to (late) Middle Ages ceramic found in different regions of Kyrgyzstan are examined. The methods consist of complementary: measurement of the hardness by the Rockwell method and determination of the density by the hydrostatic weighing method. The apparent density and the water absorption are determined and the open porosity is calculated. An integrated professional study of ceramics from different archaeological sites will make an appreciable contribution to the implementation of a strategy for the development of the Republic and will help to recreate a complete picture of Kyrgyzstan’s historical and cultural heritage.

Effect of annealing temperature on corrosion resistance of metal steel samples St52-3

In the context of increased pace of modern production, the role of heat treatment is increasing, as it is the main method for producing steels with a given structure and mechanical properties. Parts used in production must have a long service life not only at room temperature, but also have high strength characteristics at low and high temperatures. In this regard, special attention is paid to steel used for the manufacture of such parts. One of them is steel grade St52-3 (rus 17Г1C). The aim of the work was to determine the effect of quenching at various temperatures onto corrosion resistance of St52-3 steel. To achieve this goal, tasks such as studying the effect of different tempering temperatures of St52-3 steel on the value of hardness according to the Rockwell method were undertaken. After-treatment gravimetric studies were performed to identify the temperature regime of tempering that minimizes the corrosion rates. It was shown that after tempering, the hardness of the samples decreases with increasing temperature. To assess the corrosiveness of the medium for the test samples, the mass and depth corrosion indicators were calculated. The maximum corrosion rate is observed during quenching and subsequent tempering at a temperature of 300 °C, the minimum at a tempering temperature of 500 °C.

PENGARUH VARIASI MEDIA PENDINGIN TERHADAP NILAI KEKERASAN PADUAN GEAR SPROCKET AISI 1020 DENGAN TIMAH MELALUI HEAT TREATMENT

Study the effect of cooling media variations on the hardness value of AISI 1020 gear sprocket alloys and tin with heat treatment. This research is to find out the combination of AISI 1020 gear sprocket with tin, with a heat treatment process carried out with temperatures reaching 700ºC and held for 15 minutes, with air conditioning media, SAE 40 oil and water, and carried out heat treatment with hardness testing on each material with differences in the cooling media using the Rockwell method. From the results of the test, different cooling media, different cooling rates are obtained and produce different hardness changes. In testing the data obtained in accordance with the results of heat treatment which is continued by cooling the air gives the lowest hardness value (51.2 HR), while cooling with oil and water is higher, respectively 54 HR and 58.4 HR.

PENGARUH TEMPERATUR TEMPERING TERHADAP KEKERASAN DAN STRUKTUR MIKRO BAJA AISI 1045 YANG DIQUENCHING DALAM MEDIA PENDINGIN TERSIRKULASI

Steel AISI 1045 is steel classified as medium carbon steel because it has a carbon content of 0.45%.The characteristics of steel itself are sometimes not in accordance with the needs required,therefore the steel requires other treatments to change the properties and structure of steel AISI1045. The characteristics of steel can be changed by giving heat treatment, one of the processescarried out is the quenching tempering process. Quenching is a metal working process with rapidcooling to a predetermined variety of media with the aim of increasing the hardness of AISI 1045steel, while tempering is the process of reheating hardened steel with the aim of obtaining hightenacity and toughness.The quenching process uses a temperature of 800 °C with a waiting time of60 minutes and then cooled quickly with variations of diesel, water, and salt water with a 180°circulating process. While the tempering temperature variations used are 450 °C, 550 °C, and 650°C with a waiting time of 60 minutes. The results of the hardness test using the Rockwell method. inraw material testing get a value of 61.33 HRB hardness. The quenching results circulated in thesolar media are (80.6 HRB, 79.3 HRB, 81.3 HRB), the value of violence in the water media (89.3HRB, 89 HRB, 89.6 HRB), and salt water media (94,6 HRB, 96 HRB, 94.6 HRB). The hardnessvalue of temperature temperament 450 °C solar media (72.6 HRB 73 HRB, 72.6 HRB), water media(83.6 HRB, 82.6 HRB, 83 HRB), salt water (86.3 HRB, 86.6 HRB, 87.3 HRB). Temper temperaturehardness value of 550 ° C solar media namely (70.3 HRB, 70.3 HRB, 70.6 HRB) water media (81.3HRB, 81.3 HRB, 80.6 HRB) salt water media (84,3 HRB, 83.6 HRB, 84.6 HRB). The hardness valueof temperature variation of 650 °C, solar media are (68.3 HRB, 68.6 HRB, 68.6 HRB) water media(79 HRB, 79.3 HRB, 79.3 HRB) and salt water media (81,3 HRB, 81.6 HRB, 82 HRB). Themicrostructure obtained in quenching is the martensite structure and the tempering structure istemper martensite.Keywords: AISI 1045, quenching, tempering, martensite, ferrite, pearlite, HRB

Failure Analysis of Spur Gears Used in Transmission System Applied on a Hand Tractor

Damage or failure frequently occurs on gearbox gears. If this occurs in the gearbox of tractors, this can be severe. This study aimed to determine the cause of the spur gear fracture through empirical and simulation studies. The hardness test was undertaken employing the Rockwell method where the fracture surface was observed using a scanning electron microscope (SEM) in order to identify crack initiation and the type of fracture. The stress intensity factor was next analysed using the finite element method (FEM). The results of the chemical composition testing indicated that the material used was according to the AISI 8620 standard containing an element of Carbon (C) of about 0.142 %.The hardness value of the gear was 109 HRB. The observation of the fracture surface showed a brittle fracture surface, suggesting that an impact load had occurred. The simulation results using the FEM also showed that the maximum stress intensity factor and KI value occurred at the centre of the tooth. The value of KI was shown to be larger than the fracture toughness and (KIC). Therefore, this result indicates that a crack will continue to propagate until final failure.

INCREASING THE RELIABILITY OF WELDED PIPELINE CONNECTIONS IN RESERVOIR PRESSURE MAINTENANCE SYSTEM

During the field pipelines construction, electric arc manual welding is widely used for pumping water into injection wells and their subsequent overhaul or current repairs. When constructing such structures, due attention is not paid to checking welds for their geometric parameters in the process of pipe joining in the oil fields, and technical measures are not taken to increase the strength of the welded joint, which often leads to emergency situations caused by a rupture of infield water pipelines in reservoir pressure maintenance system. The article investigates the issue of the influence of the most common practical defects of welds of a one-piece joint, formed during the application of a weld when connecting butt welds by electric arc manual welding, on the strength characteristics of a welded joint by examining the condition of the pipe material being welded around the weld zone. As a test sample, a butt weld sample with obvious defects was used. The geometric parameters of the welded joint were measured using standard means and the hardness of the heat-affected zone was determined by the Rockwell method in certain areas with justification of the welding process. The cause of weakening is established. The change in the geometry of the heat-affected region is due to the accumulation of filler material during its melting on one side of the weld with a decrease in the welding speed. Recommendations are given for the prevention of the destruction of welded structures and the prevention of emergency situations in water pipelines.

Mechanical properties measurements with portable hardness testers: advantages, limitations, prospects

The article presents an analysis of the most common hardness measurement methods, implemented by portable hardness testers: rebound or Leeb method, static Portable Rockwell (PR) method and Ultrasonic Contact Impedance (UCI) method. These methods are reviewed in terms of the physical nature of the measurements and the influence of the measured sample properties and the probe parameters on the measurement result. The review contains advantages of each method, possible applications, as well as limitations due to the operation principles of probes. The article also contains the analysis of solving the problem of measurement results validity and their conformity with standardized hardness scales.

Failure Analysis of the Leaf Spring of Truck Colt Diesel Using Finite Element Method

Damage is often experienced by leaf springs of diesel trucks, known as premature failure and is need to be analyzed. Thus, this study aims to analyze the causes of failure of leaf springs through analytical and numerical analyses. Hardness testing was performed using the Rockwell method. Microstructure was observed using scanning electron microscopy to identify the fracture surface. Analytical and numerical analyses were used to obtain the load distribution of each spring. The analysis results of load distribution on each spring were 26.95 kN. The chemical composition of the specimen shows that the material was tested according to AISI 5150 standard. The hardness value of leaf springs tested was HRB 106.9. The Result of numerical and analytical shows that the strain, stress and deformation of leaf springs with maximum values occurred at the near of hole of spring. The KI value ≈ KIC, therefore this may cause crack propagation. The failure of leaf springs was caused by fatigue during the operation marked by a beach mark and the normal stress is far below the specimen fatigue strength.

Study of leaf spring fracture behavior used in the suspension systems in the diesel truck vehicles

The leaf spring is frequently applied on a vehicle such as used on the truck and it is one of the machine element suspension systems. It needs to have an excellent resistance to the fracture propagation to avoid failure that could lead to severe accidents. Fracture failure on the leaf spring is frequently experienced especially on diesel trucks, known as premature failure. Therefore, this case is needed to be studied and investigated. The purpose of this study is to investigate the cause of failure on the broken leaf spring by counting analytically the stress intensity factor (KI) occurred near the crack tip. Moreover fracture surface observation conducted by Scanning Electron Microscope (SEM) to find out whether there is or not an initial crack and crack propagation direction. This present study describes the experimental work and analytical analysis of theleaf spring used on Diesel Truck Vehicle. Hardness testing was performed using the Rockwell method. The chemical composition testing on the leaf spring material was found that the material in accordance with AISI 5150 standard. The hardness value of leaf springs tested of about 106.9 HRB. The result of analytical analysis shows that the maximum value of stress intensity factor (KI) occurred near the crack tip at the near the hole of leaf spring. In this case the value of KIis higher than thevalue of the fracture toughness (KIC) of the leaf spring material. Therefore, this result could be inferred that crack propagation happened starting from initial crack tip which is located near the hole on the leaf spring. The failure of leaf springs also caused by fatigue crack propagation due to dynamic loading during the operation marked by appearance the beach mark on the fracture surface.

ANALISA SIFAT MEKANIK DAN STRUKTUR MIKRO HASIL PENGELASAN GESEK PIPA STAINLESS STEEL AISI 304L

Friction welding is a metal connection that occurs due to heat caused by pressure/friction force due to rotation of metal one to other metal axis. In addition, spindle shaft with this process can minimize the shift axis of the welded material. The purpose of this research is to know the effect of variation of rotation speed and wrought time on mechanical properties (tensile strength, flexural and hardness) and microstructure of AISI 304L Stainless Steel pipe of friction welding. The experiment was carried out by stages of friction welding process on Pindad type lathes by varying the rotation (550 rpm, 1020 rpm and 1800 rpm) and wrought time (25 seconds, 35 seconds, 45 seconds) using stopwatch. The axial force is obtained through a power screw mechanism on the tail-stock with a forging pressure of (Pu = 28.02 MPa). Welding temperature is 1050˚C. The friction welding results are then formed into specimens for mechanical testing of tensile test specimens and standard ISO 82-1974 (E) test, DP8 size and hardness test using the Rockwell method. The test result showed that the tensile strength of the friction welding result with the highest σ max value in 1800 rpm/45 second specimen was 446,22 N/mm2 decreased when compared with raw material that is 788,62 N/mm2. the bending strength of the friction welding result with the highest σ max value in the 1800 rpm / 45 second specimen is 1470 N / mm2 decreased when compared with the raw material ie 1950 N/mm2. The highest hardness value is located in the part of the welded joint of specimen with variation of 1800 rpm / 45 second rotation of 77,5 HRA decrease from hard raw material value is 81,0 HRA. Rotation variations affect the mechanical properties of the material, the higher the engine rotation the value of its strength increases. Similarly, if the wrought time longer then the value of strength will also increase. Observations on microstructure with the variation of rotation speed and time of wrought there is a noticeable change is in the weld metal there are many austenite so that the strength and hardness value almost closer to Raw material hardness value. As for the HAZ area that there are many ferrit so that the strength and hardness value close to hardness value Raw material.