Effect of Hydrogen on the Mechanical Properties of High Strength Steels
Master thesis
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https://hdl.handle.net/11250/2826360Utgivelsesdato
2021Metadata
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Sammendrag
The main purpose of this experiment is to compare the mechanical properties of hydrogen charged and uncharged samples. This thesis work started with the machining samples of AISI 1074 rectangular bar into tensile test specimen. This whole process involved cutting, machining, heat treatment, tempering and this results to 17 samples for tensile test. To obtain this all the specimens were heated at 900 degree Celsius for 30 minutes and quenched into the oil. Later on different samples were tempered at different temperature as per the selection. They were split into 3 groups, where 2 groups were hydrogen charged with different time durations. Vickers hardness test is used to measure hardness of different samples. The next step is to induced hydrogen inside the samples for certain period of time by placing into the electrolyte with distilled water 3.5 wt. % Nacl. The sample had each an incubation period of between 14-20 days assuming sufficient hydrogen diffusion after 2 weeks. The samples from group 2 and group 3 were hydrogen charged which is done by designing and machining a canister to surround the specimen during testing where group 1 were tested in air with normal strain rate. This samples underwent normal tensile test to determine the elastic modulus, yield strength of the material. And the other group of rods were immersed inside the 3.5 wt. % NaCl and subjected to the cathodic protection, where titanium electrode were used as counter electrode for the diffusion of hydrogen inside the sample. Results were compared between all series shows clear indication of hydrogen embrittlement in group 2 and group 3.