Article Per Year (5 Year)
p-Index From 2020 - 2025
0
P-Index
This Author published in this journals
All Journal Makara Journal of Technology
Riza Iskandar
Jurusan Fisika, FMIPA Universitas Padjadjaran, Jl. Raya Bandung-Sumedang KM. 21 Jatinangor
Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Electrical & Electronics Engineering Engineering Materials Science & Nanotechnology Mechanical Engineering

Published : 3 Documents Claim Missing Document
Claim Missing Document
Check
Articles

Found 3 Documents
Search

 1 
Residual Stress Measurements on the TIG Weld Joint of 57Fe15Cr25Ni Austenitic Steel for Structural Material Applications by Means X-Ray Diffraction Techniques Parikin, Parikin; Ismoyo, Agus Hadi; Iskandar, Riza; Dimyati, Arbi
Makara Journal of Technology Vol. 21, No. 2
Publisher : UI Scholars Hub

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Measurements of residual stress on the 57Fe25Cr15Ni steel plate with no-filler TIG-welding process were carried out. This work was conducted to determine the nature of weld ability in synthesized steel. The bulks were formed in a dimension of 30x20x7 mm3 to ease data retrieval. Results show that the largest residual stress occurred in the weld metal area, amounting to 82.40 MPa with lattice stretching of 0.18%. Conversely, the values decreased to 65.92 MPa and a stretch of 0.14% in the HAZ area. This residual stress is a tensile stress that can reduce the mechanical strength of the material since it adds to the applied loads. This was confirmed by microstructure observations. The carbon content was very high in the dark lines. Weaken materials usually start from this side and could initiate the intergranular cracks that rapidly migrate among its grain boundaries.
Microstructures and Hardness of TIG Welded Experimental 57Fe15Cr25Ni Steel Parikin, Parikin; Dani, Mohammad; Rivai, Abu Khalid; Ismoyo, Agus Hadi; Iskandar, Riza; Dimyati, Arbi
Makara Journal of Technology Vol. 22, No. 2
Publisher : UI Scholars Hub

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

The microstructures and hardness of tungsten inert gas (TIG) welded experimental 57Fe15Cr25Ni steel were investigated through optical–scanning electron microscopy analyses and with a hardness tester, respectively. The welding process restructured the constituent atoms into regular and irregular crystal lattices. Rapid cooling of the weld metal allowed the formation of a dendritic (columnar) structure, with porous grains. By contrast, slow cooling influenced HAZ and led to the formation of grain structures. The crystal lattice became more organized and larger than other zones. Meanwhile, the base metal formed circular nets that covered large area inside thick and thin grain boundaries. The diffraction patterns revealed texturing in the weld metal. The crystallite orientation changed from (111) to (200) and (220) planes. The weld metal profile broadened (amorphous) and had full width at half maximum (fwhm) value larger than those in HAZ and the base metal. The weld metal possessed hardness of 121 HV, which is slightly lower than the hardness of the base metal (130 HV). HAZ exhibited the highest hardness value (152 HV). Hardening was influenced by carbon and outer oxygen migration to the grain boundaries, which formed colonies, i.e., chromium carbide, aluminum carbide, aluminum oxide, silicone oxide, and silicon carbide (precipitation hardening). Welding (heat) may change the microstructure and hardness of HAZ and the weld metal region, which would be brittle and very critical in responding to applied loads.
Comprehensive Inspection on the Experimental Ferritic Stainless Steel by Means of Transmission Electron Microscopy and Neutron Diffraction Techniques Parikin, Parikin; Dani, Mohammad; Iskandar, Riza; Jahja, Aziz Khan; Insani, Andon; Mayer, Joachim
Makara Journal of Technology Vol. 23, No. 3
Publisher : UI Scholars Hub

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

The field of physical metallurgy is one of the primary beacons that guide alloy developments for multipurpose materials such as the in-core structure materials for pressure vessel components and heat exchangers. The surface microstructure of new ferritic steel with significant local constituent materials was characterized by high resolution powder neutron diffractometer (HRPD) and transmission electron microscope (TEM), combined with the energy dispersive X-ray spectroscopy (EDX). The alloy contains73% Fe, 24% Cr, 2% Si, 0.8% Mn, and 0.1% Ni, in %wt. The charge materials were melted by the casting techniques. The neutron diffractograms obtained shows five dominant diffraction peaks at (110), (200), (211), and (220) reflection planes, which is a typical structure for a body centered tetragonal system. The pattern also included some unidentified peaks which were verified to be Al2O3.54SiO2, Cr23C6, and SiC crystals. A piece of alloy which taken from the middle of the ferritic ingots was also characterized by the HRPD; no unidentified peaks were observed. Results from the scanning transmission electron microscopy (STEM) combined with EDX analyses confirmed the neutron identified phase distributions. Also, oxides and carbides were observed to form mainly close to the surface of the steel. Cracks and pores which probably formed during the preparations were also identified close to the surface. Although the ferritic steel was successfully synthesized and characterized, some unidentified phases and defects could still be found in the produced ingots.
Co-Authors Abu Khalid Rivai Agus Hadi Ismoyo Andon Insani Arbi Dimyati Jahja, Aziz Khan Joachim Mayer, Joachim Mohammad Dani Parikin Parikin