Abstract
To avoid failures due to hydrogen embrittlement, it is important to know the amount of hydrogen absorbed by certain steel grades under service conditions. When a critical hydrogen content is reached, the material properties begin to deteriorate. The hydrogen uptake and embrittlement of three different carbon steels (API 5CT L80 Type 1, P110 and 42CrMo4) was investigated in autoclave tests with hydrogen gas (H2) at elevated pressure and in ambient pressure tests with hydrogen sulfide (H2S). H2 gas with a pressure of up to 100 bar resulted in an overall low but still detectable hydrogen absorption, which did not cause any substantial hydrogen embrittlement in specimens under a constant load of 90% of the specified minimum yield strength (SMYS). The amount of hydrogen absorbed under conditions with H2S was approximately one order of magnitude larger than under conditions with H2 gas. The high hydrogen content led to failures of the 42CrMo4 and P110 specimens.
Highlights
When steels are exposed to hydrogen, their mechanical properties can deteriorate.This phenomenon is commonly referred to as hydrogen embrittlement and has been studied for 145 years [1]
The values for hydrogen uptake presented in this work are in good agreement with findings from the literature where similar steel grades were charged in H2 gas [21,37,38,42,43]
The results show no significant temperature influence on the hydrogen absorption of the carbon steels that were tested in autoclaves under wet conditions
Summary
When steels are exposed to hydrogen, their mechanical properties can deteriorate. This phenomenon is commonly referred to as hydrogen embrittlement and has been studied for 145 years [1]. The same authors tested un-notched tensile specimens of the lower strength material and found no significant change in the UTS, while the fracture elongation was reduced at a hydrogen content of 1.2 wt. Ppm for the linepipe steel API X70 This limit, the fracture toughness of the material (YS = 583 MPa) consisting of ferrite and degenerated pearlite decreases in a linear relationship with increasing hydrogen content. Even a hydrogen pressure of 300 bar did not influence the YS and the UTS of the ferritic-pearlitic X80 pipeline steel in slow strain rate tests, while a decrease of the fracture elongation was observed [35]. Álvarez et al [42] charged the bainitic-martensitic 2.25Cr1Mo0.3V (YS = 590 MPa, UTS = 700 MPa) in 195 bar H2 gas at 450 ◦ C and measured a hydrogen content of 4.2 wt. The aim of the presented work is to generate data on the hydrogen uptake of three carbon steels under seven different conditions at two temperatures and to check whether hydrogen embrittlement occurs
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