#TITLE_ALTERNATIVE#

• Main Author: WIRAWAN (NIM : 13706011): Dosen Pembimbing : Dr. Bambang Widyanto, SIGIT
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/17229
• Institution: Institut Teknologi Bandung

Hydrogen Embrittlement is the phenomenon of decreasing the mechanical strength of metal due to interaction with the environment. Unlike the events in general corrosion, hydrogen embrittlement actually occur when metals are in <br /> <br /> <br /> <br /> <br /> cathodic conditions. When in cathodic conditions, the reduction of hydrogen ions will occur at the surface of the metal. Because of very small size of hydrogen atoms, then hydrogen atom can diffuses into the metal. Specimens used were A516 steel, and to obtain different grain size, grain growth process is carried out with different heating time, heating time that used are 45 minutes (to produce ASTM GRAIN SIZE Number 8), 90 minutes (ASTM GRAIN SIZE Number 7.5), and 120 minutes (ASTM GRAIN SIZE 7). To introduce hydrogen into the materials, the spesimen was treated in hydrogen charging with 0.5 M H2SO4 for electrolite, the current density is 15 &#956;m/cm2, while charging time is 4 hours, and graphite as anodes wan used. Mechanical strength caracterisized was measured by tensile test. From the experiments, decreases of tensile strength on samples <br /> <br /> <br /> <br /> <br /> with ASTM GRAIN SIZE Number 8.5 is 10.9%, in samples with ASTM GRAIN SIZE Number eight is 7.5%, for samples with ASTM GRAIN SIZE 7.5 Number is 5 , 8%, while in samples of ASTM GRAIN SIZE Number 7 was 2.8%. For the reduction of toughness, toughness decrease in the sample with ASTM GRAIN <br /> <br /> <br /> <br /> <br /> SIZE Numbers 8.5 is 29.5%, in samples with ASTM GRAIN SIZE Number 8 is 19.7%, for samples with ASTM GRAIN SIZE Numbers 7.5 is 11.95 %, and samples of ASTM GRAIN SIZE Number 7 is 6.7%. The decrease of mechanical properties have a tendency to decrease for each higher grain size, this was due to <br /> <br /> <br /> <br /> <br /> the greater grain size when the process of grain growth is longer, during the process of grain graowth, grain boundary regions, the density of dislocations and voids decreases, so the place for hydrogen trapped in the materials will be <br /> <br /> <br /> <br /> <br /> reduced. Another factor that have influence in Hydrogen Embrittlement mechanism is the charging time. For 4 hours charging, decreases the strength and toughness were 5.8% and 11.95%) whereas at the time of charging time is 3 hours <br /> <br /> <br /> <br /> <br /> were 3.4% and 7.6%.