Effects of silicon additions and retained austenite on stress corrosion cracking in ultrahigh strength steels
- Massachusetts Inst. of Technology, Cambridge
A study was made of the effects of silicon additions and of retained austenite on the stress-corrosion cracking (SCC) behavior of commercial ultrahigh strength steels (AISI 4340 and 300-M) tested in aqueous solutions. By comparing quenched and tempered structures of 4340 and 300-M (i) at equivalent strength and (ii) at their respective optimum and commercially-used heat-treated conditions, the beneficial role of silicon addition on SCC resistance is seen in decreased Region II growth rates, with no change in K/sub ISCC/. The beneficial role of retained austenite is demonstrated by comparing isothermally transformed 300-M, containing 12% austenite, with conventionally quenched and tempered structures of 300-M and 4340, containing less than 2% austenite, at identical yield strength levels. Here, the isothermally transformed structure shows an order of magnitude lower Region II SCC growth rates than quenched and tempered 300-M and nearly two orders of magnitude lower Region II growth rates than 4340, K/sub ISCC/ values remaining largely unchanged. The results are discussed in terms of hydrogen embrittlement mechanisms for SCC in martensitic high strength steels in the light of the individual roles of hydrogen diffusivity and carbide type.
- OSTI ID:
- 6490540
- Journal Information:
- Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 9:1; ISSN MTTAB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALKALI METAL COMPOUNDS
ALLOYS
AUSTENITE
CARBON ADDITIONS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CHROMIUM ALLOYS
CORROSION
CORROSION PROTECTION
CORROSION RESISTANT ALLOYS
CRACKS
ELEMENTS
ELONGATION
FAILURES
FRACTURES
HALIDES
HALOGEN COMPOUNDS
HEAT TREATMENTS
HYDROGEN COMPOUNDS
IRON ALLOYS
IRON BASE ALLOYS
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
OXYGEN COMPOUNDS
QUENCHING
SEMIMETALS
SILICON
SILICON ADDITIONS
SILICON ALLOYS
SODIUM CHLORIDES
SODIUM COMPOUNDS
STAINLESS STEELS
STEELS
STRESS CORROSION
SURFACES
TEMPERING
WATER
YIELD STRENGTH