Fatigue crack initiation and growth in a CrMo steel under hydrogen pressure

Abstract

International audienceAlong the hydrogen supply chain, metallic components, such as pressure vessels, compressors and valves, are facing high pressure hydrogen gas. The object of this paper is to address microstructural as well as mechanical aspects of fatigue crack initiation and growth at room temperature in a quenched and tempered (Q&T) low alloy steel under hydrogen pressure in the range 0.5e35 MPa. For such steel, the need to perform tests in-situ under hydrogen pressure is required. The influence of hydrogen gas on the total life in terms of crack initiation and crack propagation is analyzed. The experimental techniques developed to detect crack initiation in a pressure vessel under hydrogen pressure are presented. Thanks to these technical developments the influence of hydrogen gas on the total life duration including crack initiation and crack propagation is analyzed. It is shown that the effect of hydrogen pressure on crack initiation is important. At constant load ratio, the hydrogen pressure effect on fatigue crack growth (FCG) is dependent on the loading amplitude (in terms of DK). These results related to cracking behavior are enriched with information on fracture surfaces appearance. The results presented have been achieved within the European project MATHRYCE [1] dedicated to Material Testing and Recommendations for Hydrogen Components under fatigue. They are part of a process necessary to give a scientific background to the development of a design methodology where hydrogen enhanced fatigue damage is taken into account

Experimental Investigation of the Effect of Hydrogen on Fracture Toughness of 2.25Cr-1Mo-0.25V Steel and Welds after Annealing

“…There are many studies that have been performed on this topic. Briottet et al studied the fatigue crack initiation and growth in Cr–Mo steel under hydrogen pressure and indicated that, with increasing hydrogen pressure, the number of cycles needed to initiate crack formation decreased [ 7 ]. Garcia et al studied the effect of hydrogen on the tensile properties of CrMoV steels by means of the small punch test, and found that the CrMoV steel has a high susceptibility to HE [ 8 ].…”

Determination of the fatigue fracture characteristics of steel MS1700 under corrosion conditions

“…The formation of striations is not influenced by hydrogen (Kanezaki et al, 2008). Nevertheless, many authors have reported difficulties in detecting striations in fracture surfaces influenced by hydrogen (Liu and Atrens, 2017;Colombo et al, 2016;Briottet et al, 2015). Therefore, this result was expected even though it can not be explained using past literature.…”

“…Several authors have proved that hydrogen accelerates this crack nucleation process that reduces the fatigue life of steel. Briottet et al (2015) found a strong decrease in the number of cycles to crack initiation for steel 25CrMo4 (quenched and tempered). Specimens tested in a hydrogen environment showed a reduction in cycles to crack initiation of 10, relative to specimens tested in air.…”

“…It has been proved that defects on specimen increase the stress concentration and the local hydrogen content (Moro et al, 2010). When a crack initiates at a defect, its propagation is initially under the influence of the strain field induced by that defect; after some propagation this influence disappears (Briottet et al, 2015). Several authors have proved that hydrogen accelerates this crack nucleation process that reduces the fatigue life of steel.…”

“…Kanezaki et al (2008) stated that "this fundamental mechanism is not influenced by hydrogen". Nevertheless, many authors have reported difficulties in detecting striations in fracture surfaces influenced by hydrogen (Liu and Atrens, 2017;Colombo et al, 2016;Briottet et al, 2015). Huneau and Mendez (2003) found that the fracture surface morphology in the crack propagation region is dependent on the environment.…”