Equilibrium and growth characteristics of hydrogen-induced intergranular cracking in phosphorus-doped and high purity steels

Journal Article · Mon Sep 01 04:00:00 EDT 1986 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(86)90119-7· OSTI ID:6965336

Kameda, J

By means of fracture mechanics analyses, acoustic emission techniques, and fracture surface analyses by scanning Auger microscopy and X-rays, it was determined how segregated phosphorus, yield strength and grain size affect equilibrium and growth characteristics of hydrogen-induced intergranular cracking in high strength steels. The effect of yield strength on the threshold stress intensity was found to be greater than those of phosphorus segregation and grain size. The intergranular phosphorus segregation greatly accelerated the growth rate of hydrogen-induced intergranular cracking and caused a large number of acoustic signals to be emitted during the crack growth. The crack growth rate increased in a steel with segregated phosphorus and slightly decreased in high purity steels, where only occasional acoustic emissions were measured during the cracking process, by increasing grain size. Fracture surface analyses indicated more featureless intergranular fracture facets and higher levels of residual strain in the lattice adjacent to the fracture surface in the phosphorus-doped steel than in the high purity steels. These results suggest that while in steels with segregated impurities, the macrocrack tends to grow by rapid formation of intergranular microcracking which gives rise to dislocation emissions at the growing crack tip. In high purity steels, slow growth of intergranular microcracking proceeds which is accompanied by either the absence or mitigation of dislocation generation at the crack tip.

• Research Organization: Ames Lab., Iowa State Univ., Ames, IA (US)
• OSTI ID: 6965336
• Journal Information: Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 34:9; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CRACK PROPAGATION
CRYSTAL DEFECTS
CRYSTAL DOPING
CRYSTAL GROWTH
CRYSTAL STRUCTURE
DISLOCATIONS
ELEMENTS
EMBRITTLEMENT
FRACTURE MECHANICS
GRAIN SIZE
HYDROGEN EMBRITTLEMENT
IRON ALLOYS
IRON BASE ALLOYS
LINE DEFECTS
MECHANICAL PROPERTIES
MECHANICS
MICROSTRUCTURE
NONMETALS
PHOSPHORUS
SIZE
STEELS
STRESS INTENSITY FACTORS
STRUCTURAL CHEMICAL ANALYSIS
YIELD STRENGTH