Effect of Temperature and Strain Rate on the Embrittlement Behavior of Heat-Treated Carbon Steel (UNS) G10180

Effect of Temperature and Strain Rate on the Embrittlement Behavior of Heat-Treated Carbon Steel (UNS) G10180

The microstructures of plastically deformed steel have been studied to potentially promote ingress of atomic hydrogen raising its susceptibility to embrittlement. The as- received UNS G10180, heat-treated to about 500oC was investigated to have experienced ductile to brittle transition effect leading to the resultant drop in mechanical duty. The apparent embrittlement of the specimen came after series of controlled pre-stressing by quasi- static loading (fatigue cycling) followed closely by pre-charging of the specimen with hydrogen in an ambient electrochemical environment of hydrochloric acid. Standard tensile test were hydrogenated from 2 to 6 hours and deformed by cold worked to 40%, 50%, 60% and 80%   mechanical and laboratory tests on the dissolution and dissociation mechanism of the ions. The crack length and time of failure at low strain situations was evaluated under the simulated conditions. The results showed that by calculation, pre-charging with hydrochloric acid raised the susceptibility of embrittlement of hydrogen specie by 25%. Increment in temperature of the electrolytic bath by every 25oC for the number of experimental hours further raised the susceptibility of the failure of the metal by 15%. This led to lower tensile strength or low bearing capacity by almost 10% compared to the as-received samples. The strain also decrease due to pre-stress and pre-charging at the temperatures used. It can therefore be said material like UNS steel can fail without apparent deformation in the field assuming if subjected under high temperature and under high loading, complemented by presence of acid attack.

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