Analisis Variasi Arus Pengelasan Kombinasi SMAW-FCAW dengan Kampuh Double V-Groove terhadap Kekerasan dan Struktur Mikro Dissimilar Material JIS G3101-SS400 dan ASTM A36

This study aims to determine the effect of variations of the current with combining two welding techniques SMAW and FCAW in double v-groove against the hardness and microstructure of the dissimilar material of JIS G3101-SS400 and ASTM A36. JIS G3101 SS400 and ASTM A36 each with a thickness of 10 mm were used as the materials. The combination of SMAW welding with E7018 electrodes and FCAW with E71T-1 were used as the welding techniques. The current used in SMAW welding were 60 A, 75 A, and 90 A. While in FCAW welding the current used were 190 A, 205 A, and 220 A. Hardness and microstructure tests were carried out on each sample. The results of the study showed that the current in welding process affect the hardness value and microstructure of material. The higher the welding current, the value of hardness of the material going to decrease and vice versa. The highest hardness values in SMAW and FCAW welding are at currents of 60 A and 190 A. Then the current in the welding process also affect the microstructure produced in the weld and HAZ. The formed microstructure containing pearlite and ferrite. The higher welding current, the percentage of pearlite produced increase and the percentage of ferrite decrease.

Experimental investigation on foamed concrete produced using a planetary ball mill

The experimental study is devoted to investigation on foamed concrete produced applying innovative intensive mixing technology by using a planetary ball mill. Modern type of foamed concrete represents cementitious composite material group which may be competitive with traditionally used autoclaved aerated concrete. Innovative mixing method makes possible stabilizing of foamed concrete mixture and improving the microstructure of material. The aim of this study is to investigate physical and mechanical properties of non-autoclaved concrete such as density and compressive strength, and capillary water absorption depending on intensive mixing time. In this research microstructure, such as pore size diameters, depending on mixing time is also analysed.

Comparative Study of Chip Formation in Orthogonal and Oblique Slow-Rate Machining of EN 16MnCr5 Steel

In today’s unmanned productions systems, it is very important that the manufacturing processes are carried out efficiently and smoothly. Therefore, controlling chip formation becomes an essential issue to be dealt with. It can be said that the material removal from a workpiece using machining is based on the degradation of material cohesion made in a controlled manner. The aim of the study was to understand the chip formation mechanisms that can, during uncontrolled processes, result in the formation and propagation of microcracks on the machined surface and, as such, cause failure of a component during its operation. This article addresses some aspects of chip formation in the orthogonal and oblique slow-rate machining of EN 16MnCr5 steel. In order to avoid chip root deformation and its thermal influence on sample acquisition, that could cause the changes in the microstructure of material, a new reliable method for sample acquisition has been developed in this research. The results of the experiments have been statistically processed. The obtained dependencies have uncovered how the cutting tool geometry and cutting conditions influence a chip shape, temperature in cutting area, or microhardness according to Vickers in the area of shear angle.

Influence of Microstructure on Machinability of Material and its Final Surface Quality

Mechanical properties, such as hardness, yield strength and tensile strength, are very often considered as the only key factor for selecting technological parameters of materials machining. Analysis of the microstructure and specific microstructural parameters is not performed until serious problems occur during otherwise common machining processes. This study reports a few case studies, dealing with such problematics, which resulted from underestimation of the knowledge of macrostructure and microstructure of material. It deals with problems such as uncommon surface defects after machining or impossibility to use current technological machining processes when machining new batch of material.

Analysis of Plastic Deformation of Double Reduced Sheets

This paper discusses the causes and the effects of plastic deformation of double reduced sheets under uniaxial and biaxial loading. It focuses on the specific inhomogeneity and localization of plastic deformation, which is analysed in detail. The uniaxial and the hydraulic biaxial tensile tests were used for material testing and the results were compared and evaluated. The final part of the paper deals with the microstructure of material deformations.

Direct Computational Method for Life Prediction of UD Fibre Reinforced Polymers Based-on Plasticity-Damage Simulation

New direct method was developed for fibre reinforced polymers subjected to fatigue loading. Constitutive model is based-on coupled plasticity-damage framework. Microstructure of material is satisfying the periodic conditions. Influence of microstructure has been involved through stress concentration tensor. Plasticity yield surface is described by modified Raghava criterion. Damage of matrix and transverse cracking are governed by quadratic damage surface. Method was examined on the standard example of unidirectional composite plate with carbon-fibre reinforced. Significant reduction of calculation time has been achieved using the direct computational algorithm.

Surface Hardness Changes after Strengthening under Low-Amplitude Loads

This document investigated the changes of the surface hardness of the front axle and transmission gear after strengthening under low-amplitude loads below the fatigue limit (SLAL). The experimental results showed that the strength changes of the front axle after strengthening under low-amplitude loads was almost proportional to hardness, but it was inverse ratio for the transmission gear. There was no difference in the change direction of surface hardness, caused by strengthening or damaging. The reason of surface hardness changes could be due to that the microstructure of material was improved after being strengthening under low-amplitude loads below the fatigue limit.

Effects of Microstructure on Mechanical Properties of HRS Processed SUS316L Stainless Steel

Mechanical milled SUS316L stainless steel powder is applied to hot roll sintering (HRS) process. Microstructure and mechanical properties of the HRS material is investigated. Microstructure of material produced by HRS process consists of the shell and core hybrid microstructure, that is, a shell structure with nano grains and a core structure with work-hardened coarse grains. The fine grain structure corresponding to the shell area has (austenite + sigma) nano duplex structure. Work-hardened structure in the core area composes of an austenite phase. The HRS material demonstrates not only superior strength but also enough elongation. Mechanical properties are strongly influenced by the shell/core structure, such as grain size, shell/core size and/or the volume fraction. The shell and core nano-duplex hybrid microstructure by the HRS process has been proved to be very effective to improve mechanical properties.