HEAT AFFECTED ZONE MICROSTRUCTURE OF WELD JOINT PREPARATION IN ARTIFICIAL MANNER

This paper presents two possibilities of martensitic (fine grain and coarse grain) microstructure preparation. These microstructures are present as sub-zones in the heat-affected zone of welded joints, but due to the narrow region of HAZ in a real weld, only a few tests are possible to perform such as micro-hardness. Welding simulator and laboratory furnace were used as methods for the preparation of the specimens. The material used in this study was a Nickel Molybdenum alloy steel (18CrNiMo7-6). Investigation of the mechanical properties of sub-zones of the HAZ of this particular alloy steel, were done by applying proper thermal cycles. Hardness and diameter of grain size were measured, tensile strength is calculated and Charpy instrumented test of both microstructures were performed in room temperature. The difference in Impact toughness was remarkable due to the difference in microstructure, energy for initiation and propagation were calculated by comparing (F-t and E-t) diagrams for both microstructures. The study revealed that the preparation of specimens with microstructure as at welded condition is possible, and it could lead to prepare samples for investigation of other mechanical properties such as fatigue crack growth and fracture toughness test

Utilization of FlexSim Software to Identify the Suitable Layout Planning of Production Line

The possibility of increasing production capacity by re-designing the actual layout and material flow at the Elsam factory is explained in this article. Planning of the actual layout needs some improvements because it does not meet customer demand. The actual layout is found to be disorganized on material flow which leads to a decrease in production capacity. Three different layouts are considered and analyzed. A comparison between the proposed and actual layout is shown to find out the influence on production capacity. According to the data taken from simulation software FlexSim, significant improvement is foreseen. This study reveals that redesigning the layout ensures an increase of production capacity and decrease the possibilities of accidents during transportation between consecutive workstations by decreasing the traveling distance

Vpliv mikronapak na lastnosti pri utrujanju drobno zrnato toplotno vplivanega področja na nikelj-molibdenovem jeklu

This research presents two possibilities to prepare and test the Fine Grain of a Heat Affected Zone, which, practically, could be considered as the weakest part of welded joints in the presence of any microdefect. It is a narrow zone located between the fusion zone and the unaffected base materialtherefore, only a few methods are suitable to test its mechanical properties. The 18CrNiMo7-6 steel was used as the base material. As this steel is usually used for the production of dynamically loaded components, testing of its fatigue behaviour and fracture toughness was crucial, but also measurement of its hardness and impact toughness. To investigate the mechanical properties of a Fine-Grain Heat-Affected Zone (FG HAZ), two different methods for simulation of as-welded microstructures were used in this research: A weld thermal cycle simulator (WTCS) and austenitising in a laboratory furnace +Ta raziskava predstavlja dve možnosti za pripravo in preskušanje drobnozrnate toplotno prizadete cone, ki bi jo praktično lahko šteli za najšibkejši del varjenih spojev ob prisotnosti kakršne koli mikrodefekcije. Gre za ozko cono, ki se nahaja med cono taljenja in neoviranim osnovnim materialom, zato je za preskušanje njenih mehanskih lastnosti primernih le nekaj metod. Kot osnovni material je bilo uporabljeno jeklo 18CrNiMo7-6. Ker se to jeklo običajno uporablja za izdelavo dinamično obremenjenih sestavnih delov, je bilo ključno preskušanje njegovega obnašanja pri utrujanju in lomne trdnosti, pa tudi merjenje njegove trdote in udarne žilavosti. Da bi raziskali mehanske lastnosti toplotno prizadete cone s finimi zrni (FG HAZ), sta bili v tej raziskavi uporabljeni dve različni metodi za simulacijo mikrostruktur med varjenjem: Simulator toplotnega cikla varjenja (WTCS) in avstenitizacija v laboratorijski peči + kaljenje z vodo (AF+WQ). Mikrostruktura simuliranih vzorcev je bila zelo podobna resnični zvarjeni FG HAZ. Vzorci WTCS so imeli trdoto 419 HV, KV = 101,5 J, ΔKthR = 3,40 MPam0,5, C = 1,64 × 10-11, m = 2,4465. Pri vzorcih AF+WQ je bila trdota 425 HV, KV = 73,1 J, ΔKthR = 4,33 MPam0,5, C = 1,73×10-11, m = 2,5114. Trdota pravega zvara FG HAZ je bila 405 HV. Primerjava rezultatov za obe vrsti simuliranih vzorcev, med seboj in z rezultati za pravo HAZ zvara, je potrdila, da sta obe vrsti simuliranih vzorcev primerni za mehanske preskuse posameznih podobmočij Območje, na katerega vpliva toplota

Optimizing Welding Parameters of Submerged Arc Welding based on Hardness in S235JR Construction Steel

This paper details the influence of the welding parameters of submerged arc welding in the hardness of welded joint of S235JR construction steel. The planned experiment work is conducted in the semiautomatic submerged arc welding machine and the contribution of each factor has been considering, such as: (intensity, voltage, trolley welding speed, diameter of the wire, wire speed, cooling speed of the welded joint, OK Flux 1071, chemical properties of material and wire). The results of the present investigation indicate that the welding voltage, current intensity and environment of cooling of the welded joint are the most significant factors that controls the hardness of bead. Optimal results were obtained by using the tension of 37 V, intensity of 350 A at a trolley speed of 6.0 mm/s and wire diameter 2.4 mm process, and how it helps to optimize the number of test cases that need to be done

Errors in Distance and Angle Measurements of Ultrasonic Sensor HC-SR04

This project presents the measurement of distances and angles by means of Arduino Uno microcontroller and Ultrasonic Sensor HC-SR04. Accuracy on distance and angle measurements of the sensor has been investigated. The change of object distance in motion is displayed and monitoring of the change of the angle and position. Data measurements were compared with the real measurement unit of the meter to observe their deviation, 1.6% of the standard deviation is observed between real measurement and sensor data, meanwhile, at the angle data measurements were no deviation is observed

Static Analysis of Welded Bead of Street Lighting Construction

Public lighting is for sure of unique importance for our safety, but it is also crucial to ensure that the street lighting construction does not fail due to static load or when unpredicted additional loads (like wind storms) could potentially be subjected to. To ensure that the failure of the street lighting construction will not happen, the mechanical properties of the weld joint should be known. Tensile test and hardness measurements were used as destructive examination methods and visual inspection using the welding gauge as a nondestructive examination for measurement of reinforcement and weld size. Finally, static analysis is performed by simulation in SolidWorks software, and the results were compared with the experimental test. Based on the results should be no concern, if the inspection is done properly before, during, and after welding by IWS (International Welding Specialist) personnel and in accordance with WPS (Welding Procedure Specification) and PQR (Procedure Qualification Record)

Simulation and Mechanical Properties of Fine-Grained Heat-Affected Zone Microstructure in 18CrNiMo7-6 Steel

Heat-affected zones (HAZs) in real welds are usually quite narrow, and consequently most standard mechanical tests are difficult or even impossible. Therefore, simulated microstructures are often used for mechanical tests. However, the most often used weld thermal cycle simulator produces only a few millimeters wide area of simulated microstructure in the middle of specimens. Consequently, these kind of simulated specimen are not suitable for standard tensile tests, and even for Charpy impact tests, the simulated area can be too narrow. Therefore, to investigate the mechanical properties of a fine-grain heat-affected zone in 18CrNiMo7-6 steel, two methods were used for simulation of as-welded microstructures: (a) a weld thermal cycle simulator, and (b) as an alternative, though not yet verified option, austenitizing in a laboratory furnace + water quenching. The microstructures were compared and mechanical properties investigated. The grain sizes of the simulated specimens were 10.9 μm (water-quenched) and 12.6 μm (simulator), whereby the deviations from the real weld were less than 10%. Both types of simulated specimen were used for hardness measurement, Charpy impact tests, and fatigue tests. Water-quenched specimens were large enough to enable standard tensile testing. A hardness of 425 HV, yield strength Rp02 = 1121 MPa, tensile strength Rm = 1475 MPa, impact energy KV = 73.11 J, and crack propagation threshold ΔKthR = 4.33 MPa m0.5 were obtained with the water quenched specimens, and 419 HV, KV = 101.49 J, and ΔKthR = 3.4 MPa m0.5 with the specimens prepared with the simulator. Comparison of the results confirmed that the annealed and quenched specimens were suitable for mechanical tests of FG HAZs, even for standard tensile tests. Due to the use of simulated test specimens, the mechanical properties determined can be linked to the FG HAZ microstructure in 18CrNiMo7-6 steel