CONDITION OF THE TREATED SURFACE OF NIOBIUM-BASED ALLOY WHEN GRINDING FROM SILICON CARBIDE

The study of the surface of silicon carbide after grinding niobium was carried out on a Versa 3D electronic microscope. It is shown that as a result of the grinding, traces of the grinding wheel material are formed on the treated surface, and the ground material itself is prone to adhesion to the grinding wheel. As a result of cohesive interaction, the metal adhering to the grinding wheel is transferred, and vice versa. And, as a result of adhesion-fatigue processes, mechanical action, there is a hanging wear of the grinding wheel and the indentation of individual crystals of silicon carbide into the surface of the metal being processed. This article examines such features of the behavior of niobium, when grinding it with silicon wheels and is considered from the standpoint of the electronic structure of the metal atom.

A Pin-On-Disk Study of Rail and Wheel in Dry and Mist Environments

The railways operate in various varying environmental conditions. The working environments affects the tribology of the rail and wheel contact. Therefore, the tribological properties of rail and wheel contact become important to study in these conditions. Commonly, rail and wheel contact functions under mist and wet conditions. The present study is conducted to analyse the behaviour of friction force and wear under dry, water with MQL and wet condition. The MQL is used to generate the mist condition. The study is performed on pin-on-disk tribometer in which pin is made of rail track material and disk is made of wheel material. From the experiments it was found that the friction force and wear both decreases significantly for mist condition as compared to dry condition and is least for wet condition. It was also noted that if load is increased the friction force and wear depth are also increases under all three conditions.

PERANCANGAN ALAT TANAM BENIH PADI SEMI OTOMATIS MENGGUNAKAN METODE QUALITY FUNCTION DEPLOYMENT STUDI KASUS PETANI DI KECAMATAN BALONGPANGGANG, GRESIK

Indonesia is an agrarian country where most of the population works in agriculture or farming, and the crops planted by farmers in Indonesia are rice, but in the process of planting it still uses traditional tools, it is very time-consuming, cost and labor of farmers is very ineffective and inefficient in the processing. By using the method of distributing quality functions, it is hoped that semi-automatic rice seed planting products can be created which can reduce the performance of farmers. In the data collection process consisted of 50 respondents who worked as farmers in Balongpanggang sub-district, Gresik Regency. And get the results of the technical characteristics of this product include the shape of the circle tool, the shape of the hand grip tube, the hole is automatically obtained, the color of the tool is black, 12 holes planting holes, the material for holes is using iron, no need for tools, permanent planting hole, using stainless spring , handwork using iron wrapped in rubber, the length of the flexible tool, the design is minimalist and simple, the distance between holes 20 cm, the capacity of the seeds of 3 kg and the main wheel material PVC pipe. And requires a manufacturing fee of Rp. 665,500.00. This semi-automatic rice seed planting tool has the advantage of having 2 planting grooves that apply the principle of planting legowo rows and the price of relatively affordable products.

Effects of Molybdenum Addition on Rolling Contact Fatigue of Locomotive Wheels under Rolling-Sliding Condition

Rolling contact fatigue (RCF) damages often occur, sometimes even leading to shelling on locomotive wheel treads. In this work, the RCF damage behaviors of two locomotive wheel materials with different molybdenum (Mo) contents were studied, and the influence of depth of wheel material was explored as well. The result indicates that with the increase in the Mo content from 0.01 wt.% (wheel 1, i.e., a standard wheel) to 0.04 wt.% (wheel 2, i.e., an improved wheel), the proeutectoid ferrite content and the interlamellar spacing of pearlite decreased, the depth and length of the RCF cracks increased and the average RCF live of locomotive wheel steel improved by 34.06%. With the increase in the depth of material, the proeutectoid ferrite content and the interlamellar spacing of pearlite increased, the depth of RCF cracks increased, the length of RCF cracks of wheel 1 increased and then decreased whereas that of wheel 2 decreased, the RCF live showed a decrease trend for wheel 1, while the RCF life increased and then decreased for wheel 2. The processes of shelling can be divided into three patterns: cracks propagating back to the surface, crack connection and fragments of surface materials.

An Ordinary State-Based Peridynamic Model for Fatigue Cracking of Ferrite and Pearlite Wheel Material

To deal with a new-developed ferrite and pearlite wheel material named D1, an alternative ordinary state-based peridynamic model for fatigue cracking is introduced due to cyclic loading. The proposed damage model communicates across the microcrack initiation to the macrocrack growth and does not require additional criteria. Model parameters are verified from experimental data. Each bond in the deformed material configuration is built as a fatigue specimen subjected to variable amplitude loading. Fatigue crack initiation and crack growth developed naturally over many loading cycles, which is controlled by the parameter “node damage” within a region of finite radius. Critical damage factors are also imposed to improve efficiency and stability for the fatigue model. Based on the improved adaptive dynamic relaxation method, the static solution is obtained in every loading cycle. Convergence analysis is presented in smooth fatigue specimens at different loading levels. Experimental results show that the proposed peridynamic fatigue model captures the crack sensitive location well without extra criteria and the fatigue life obtained from the simulation has a good correlation with the experimental results.

Wear Behavior of Ductile Iron Wheel Material Used for Rail-Transit Vehicles under Dry Sliding Conditions

A ductile iron wheel used for a rail-transit vehicle was treated with a recommended heat-treatment process. The ductile iron wheel after heat treatment was composed of graphite nodules and tempered sorbite with an area fraction of 98%. A friction test of the ductile iron and carbon steel wheel materials was systematically performed under different normal loads and sliding velocities. The results indicated that the wear mechanism of the ductile iron wheel changed from adhesion to abrasion with an increase in the normal load level. Adhesion was the main wear mechanism at different sliding velocities and normal load level. The impact of the normal load on the wear mechanism was greater than that of the sliding velocity. Since the ductile iron wheel material had excellent thermal property and higher carbon content, it exhibited a lower wear rate, a smaller difference value of the friction coefficient, and plastic deformation on the worn surface than those of the carbon steel wheel material. This indicates that ductile iron wheels may have a longer wear life, greater traction, and higher stability during operation than carbon steel wheels. The iron wheels have the potential for being applied in rail-transit vehicles.

Non-destructive testing of welded fatigue specimens

Non-destructive tests were conducted on welded fatigue specimens prepared using the same steel material and welding method as the one used in the manufacture and repair procedures of a KRUPP SchRs 600 bucket wheel excavator to reveal any defects present. The chemical composition, the mechanical properties, tendency to cracks and the microstructure of the bucket wheel material were determined using appropriate tests. The initiation of cracks and their subsequent growth during fatigue testing of the welded specimens was studied using ultrasound testing (UT) and a metallographic examination in order to investigate the causes of failure during service and predict fatigue life of the bucket wheel welded parts. It was found that the welding method used produces welds with numerous discontinuities that can only be detected using ultrasound techniques.