Advanced Materials Research Vol. 1128

Abstract: The earthmoving equipment milling teeth of the are made of a cutting tip (made of tungsten carbide) which, by means of the direct contact with the environment, creates the effect of penetration, dislocation and body (of alloyed steels), designed so as to achieve a spinning effect around its own axis for a uniform wearing of the tooth. The researches carried out and presented in this paper were meant to increase the durability and reliability of the milling teeth by increasing the resistance to wear of the tapered parts of their tips by means of welding build-up, using the MIG/MAG-Cold metal welding procedure, with circular welding seams, using special fillers.

Abstract: The pipelines used for carrying fluids and gas, made of specially designed steels in keeping with their intended uses, are obtained by welding on generator or by spiral welding, in a wide range of diameters (from 350 to 1800 mm) and pipe wall widths (between 6 and 40 mm). At present, the following welding procedures are used: automatic submerged arc welding (with 1 and 2 wires), combined with the unilateral or bilateral MIG/MAG welding procedure, according to plate thickness and edge working method. Ongoing researches focus on improving the end product [1, 2, 3, 4, 5, 6] by replacing the submerged arc welding procedure with other welding procedures which use less energy and have high deposit rates. This paper presents the results obtained by using tandem MAG welding, with two wires (2 x ø1.2 mm), in welding Y joint X52MS steel plates. The welds were carried out using a QUIROX 315 welding robot, with a 2-wire tandem MIG/MAG welding head, supplied by 2 QUINTO-GLC 603 welding sources, equipment found at Research Centre C12, Advanced Welding Eco-Technologies, owned by ICDD - UTBV. The results of the tests (carried out as per the enforceable regulations) concerning the characterisation of the executed welds proved that it is possible to obtain welds with lower energy use and lower material-relates costs and high productivity and quality.

Abstract: The present research is dedicated to weldability of Austempered Ductile Iron (ADI) and Ductile Iron (DI) using Shielded Metal Arc Welding (SMAW) and Gas Tungsten Arc Welding (GTAW) methods. The welds were done using the arc welding process with Nickel base filler materials: ENi-Cl and ENiFe-Cl-A. Each weldment was examined visually, with X-rays and mechanical tests. After the mechanical tests, tensile test and impact properties of the welded joint are lower than mechanical properties of the ADI base material using ENiFe-Cl-A filler metal and GTAW process. This type of filler metal ENiFe-Cl-A can be applied successfully only for repair by welding of ADI parts. Using ENi-Cl filler metal with GTAW process applied to DI, the mechanical tests, tensile test and hardness of the welded joint are greater than mechanical properties of the DI base material. This procedure can be applied for welding. In case on DI welded using SMAW with ENi-Cl electrodes, the hardness of the welded joint is lower than the hardness of base material. This procedure can be applied only for repair by welding.

Abstract: The vertical MAG welding procedure is a difficult position to be executed because the trend of the molten bath flowing. This article aims to present the achievement of vertical welding joints with a linear device with a radial oscillation system that should achieve automatic vertical welds and the correlation of the welding parameters with the movement of the welding torch in order to obtain these, using the MAG procedure, protective gas M 21 (82% argon + 18% CO₂), welding wire SG2, the material of the welded pieces S 355 JR. Samples will be cut from the welded steel plates and they will be characterized from the mechanical point of view (hardness, microstructure and macrostructure).

Abstract: Obtaining welded pipes with a superior toughness and plasticity of weld seam is strictly related to the properties of steel utilized in manufacturing welded pipes and firstly to its weldability. As a consequence, experimental research has been focused on obtaining steel with a lower equivalent carbon content but presenting high toughness and plasticity properties. In order to compensate for the decreased mechanical strength of the steel caused by reducing the carbon and manganese contents, in the first stage micro-alloying has been applied with niobium (0.040-0.055 % wt. Nb) to a construction steel, with a reduced content of carbon and manganese. The results of the mechanical characteristics obtained on hot rolled coil were good, but in the cold rolling process of pipes, the toughness characteristics have decreased excessively due to severe cold working characteristics of this steel. The second stage of experimental research has utilized microalloying with titanium (0.015-0.025 % wt. Ti), simultaneously with reducing the niobium content to a maximum level of 0.030% wt. Nb. Also, in order to reduce the cold brittleness of the steel, the maximum phosphorus content has been limited to 0.010 % wt. It was obtained excellent results with respect to the material toughness (evaluated by the impact test on KV specimen), the toughness value going up from 30-40 Joules to 150-180 Joules, while maintaining the excellent results previously obtained for steel weldability as well as the overall mechanical characteristics.

Abstract: The aim of the present paper is to establish the optimal parameter values of the cutting regime of a milling process. The paper presents a study regarding the influence of the cutting parameters on the surface roughness of the material and also on the vibration generated by their combinations, during a processing by milling. The studies are made on samples made from S355 JR steel with a metal milling machine FUS 25, which is used also for the experiments. The samples dimensions are 210x150x16mm. For the experiments there was used a cylindrical - frontal milling tool, with 32mm diameter and 10 tooth. Basic parameters of milling processing of materials we have considered in this paper are: feed rate [mm/min]; cutting speed RPM [rot/min]; depth of cut [mm]. For each of this parameters three levels were envisaged. For a 100% accurate experiment results at least 27 experiments must be done. Using an L₉ orthogonal array, the number of experiments is reduced to nine and the accurate of the method is around 99.96%. The optimal process parameters values are obtained using Taguchi method considering three situations. In the first case the goal is to get only a fine roughness for the sample. The second studied case is focused on finding a low level for the vibration generated during the milling process. The aim of the last study is to find a fine roughness and also a low level of vibration for the process. The analysis of variance (ANOVA) is applied, in all cases, in order to estimate the error variance and to rank the process parameters according to their importance.

Abstract: In a series of processes which occur in various processing industries, it is necessary that the raw materials, finished products or intermediate products to be grind to accelerate the technological phase, to obtain a product from raw materials or even only for commercialization the products [1]. Modeling program can be used to study and understand the behavior of an individual grain under compression stress. The results from previous studies have shown that the modeling program can be used [2] for predicting the grain deformation, the compression stress and the energy consumption obtained as a consequence of the grain compression process. This paper presents a comparison of a modeling and experimental study on the influence of the physical properties of a single corn seed on compression grinding process. The mathematical model by finite element method for the corn compression process is made in order to establish the forces that appear to the first cracks of the grain, to determine the maximum force of the corn compression, the deformations of the grain resulted after the compression and the energy consumption during the compression process. For this simulation it was used the mechanical structural module in 3D space of the COMSOL Multiphysics software. The experimental researches were carried out on an individual corn seed, using the materials testing machine Zwick / Roell 5 kN, to which was adapted the compression device [3]. In the experimental researches have been followed the same properties as at the mathematical modeling.

Abstract: In this paper is presented an experiment whose aim is to determine the cutting forces that appear when machining Ti6Al4V titanium alloy, in order to optimize its working rate and productivity. This experiment uses carbide coated milling tools for milling titanium alloy. It has studied the influence that milling parameters have upon the three dimensional cutting forces. The equipment which was used included stationary dynamometer for measuring cutting forces, with piezoelectric transducers. The cutting force model is developed in terms of cutting speed, feed rate, axial depth and length of milling (radial depth), with values established according to response surface methodology in intervals from the specialised literature. Titanium alloys are a continuous challenge. This paper is important because is getting relevant results for improving manufacturing efficiency.

Abstract: Parametric optimization model was made by now for abrasive water jet process, only for materials with uniform hardness. Pieces, subject to deep carburized treatment with high hardness in layer and softened in core, have a different behaviour and it is necessary to estimate new values of the system processing. Experiments consisted in cutting with abrasive water jet of rectangular samples with 10 mm thickness and deep carburized layers with 8 mm thickness, obtained as a result of deep carburized heat treatment. Abrasive water jet, initially meets the carburized layer with 62 HRC, after perforation followed the layer with fine sorbite structure (30 HRC). The different hardness causes a change in the trajectory of abrasive particles, determining deformations and micro cracks in materials to the limits of carburized layers. Choosing an optimal cutting regim becomes important not only economically, as well as qualitative. Measurements allow drawing conclusions that can be generalized to the materials with different hardness.

Abstract: This paper presents the results of experimental research on the possibility of using bronze chips recovered from the cutting process of the molded sliding bearings to obtain new sintered sliding bearings. This paper presents the results of experimental research on the possibility of using bronze chips recovered from the cutting process of cast sliding bearings in developing new sintered bearings). The cooper-tin alloys have many applications in the industry and they are usually used as antifriction materials to sliding bearings construction. Chips recovered from cooper-tin resulted from the cutting process were used to obtain metal powders in planetary mills. Recovered powders were then compacted to a unilateral mold and then were applied a sintering cycle in argon. To the obtained samples we applied wear tests in conditions of dry friction to prove the possibility of use as anti-friction material for sliding bearings in similar conditions to those obtained from industrial powders.