Study of hydrogen embrittlement in lath martensitic steels
Hydrogen assisted brittle fracture was characterized in lath martensitic steels. Hydrogen assisted intergranular fracture and transgranular brittle fracture were the main interests of this study, since these two brittle fracture modes control susceptibility to hydrogen embrittlement. The sources of metallurgical flaws that result in brittle fracture were identified and modifications to overcome these flaws are suggested. First, the source of intergranular fracture was identified in 5.5 Ni steel. High resolution scanning Auger spectroscopy analysis showed that impurity segregation on grain boundaries was the main cause of intergranular cracking. Next, the microstructural feature resulting in hydrogen assisted transgranular brittle fracture was characterized in 5.5 Ni steel and HY 130 steel. Fracture surfaces generally followed martensite lath boundaries. Interlath microcracks were found frequently in the substructure just beneath the fracture surface. 5.5 Ni steel was three-step (QLT) heat treated to introduce precipitated austenite along the lath boundaries. Experimental results showed, however, that the precipitated austenite decreased the toughness and the ductility in the presence of hydrogen.
- Research Organization:
- California Univ., Berkeley (USA)
- OSTI ID:
- 6872760
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103 -- Metals & Alloys-- Mechanical Properties
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
BRITTLENESS
CARBON ADDITIONS
CRACKS
CRYSTAL STRUCTURE
EMBRITTLEMENT
FRACTURE PROPERTIES
GRAIN BOUNDARIES
HEAT TREATMENTS
HYDROGEN EMBRITTLEMENT
IRON ALLOYS
IRON BASE ALLOYS
MARTENSITE
MECHANICAL PROPERTIES
MICROSTRUCTURE
STEELS