#TITLE_ALTERNATIVE#

• Main Author: LINDRA (NIM 13701009), YUDI
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/11663
• Institution: Institut Teknologi Bandung

Cast heat resistant austenitic stainless steels, H series (HK, HP, Micro-alloyed HP), produced by centrifugal casting are used extensively in a broad range of high temperature applications. Under the influence of temperature and stresses, the heat resistant materials will creeping, where materials microstructures change by transformations, segregations, and precipitations.<p>In this research, microstructure and hardness of four stress-rupture test samples were investigated. Specimen 1, 2, and 3 were exposed at constant temperature of 1140 K (867 oC) with varying load; 1290 N (specimen 1), 1495 N (specimen 2), and 2000 N (specimen 3). Specimen 4 was exposed to 1173 K (900 oC) and 2800 N. Microstructural changes in the HPNb-Modified were examined using both Optical Microscope and Scanning Electron Microscope (SEM) respectively. Quantitative phase measurement was conducted to measure carbides volume fraction and the grain size. Hardness test conducted by using microvickers and Rockwell C methods.<p>Microstructure investigation result shows the existence of microvoids due to grain boundary sliding, the formation of secondary carbide, and grain growth. Grain growth will decreases the hardness of materials.<p>Hardness of each specimen increased compared to that of as cast specimen. The hardness increases from 89 HRC to 91 HRC, 95 HRC, 97 HRC, dan 98 HRC. The increase in hardness is caused by the increase in carbide volume fraction, from 5,4 to 10, 12, 13, dan 14%, due to thermal and mechanical loads. <br />