Fatigue cracking in materials with brittle surface coatings

Journal Article · Thu Jul 15 04:00:00 EDT 1993 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(93)90315-J· OSTI ID:6348449

Suresh, S; Sugimura, Y; Ogawa, T ^[1]

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1. Brown Univ., Providence, RI (United States)

Ceramic coatings enhance the resistance of metal alloys to wear, oxidation, thermal exposure, corrosion, erosion and delamination in a variety of structural, optical, electrical , electronic and bioengineering applications. Recent experimental work on steel-steel bimaterials has shown that the conditions for the growth or arrest of a fatigue crack, which approaches the interface between the two steels perpendicularly, are determined by whether the crack propagates to the interface from the weaker or the stronger material. Specifically, it is found that as the fatigue crack advances toward the interface from the weaker steel, the interaction of the crack-tip plastic zone with the interface results in the arrest of the crack. However, when the fatigue crack is propagated from the stronger to the weaker steel, crack growth occurs unimpeded through the interface. In this paper, the authors present additional experimental and mechanistic descriptions of fatigue crack growth normal to interfaces. They then apply the mechanisms underlying these experiments to the design of fatigue-resistant surface coatings for alloys. In particular, they demonstrate experimentally that a fatigue crack emanating from the brittle outercoating and advancing into the substrate can be arrested and/or deflected by proper choices of ductile interlayers. Experimental results of fatigue crack profiles and high-cycle fatigue lives are presented for two different coated materials: a steel coated with a Cr[sub 2]O[sub 3] layer and a steel coated with a Cr[sub 2]O[sub 3] outerlayer and a soft Ni-Al interlayer. The paper also includes a brief discussion of the application of proposed concepts to nitrided titanium alloys.

• OSTI ID: 6348449
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 29:2; ISSN SCRMEX; ISSN 0956-716X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALLOYS
CERAMICS
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COATINGS
CRACK PROPAGATION
DESIGN
DUCTILITY
FATIGUE
INTERFACES
IRON ALLOYS
IRON BASE ALLOYS
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PROTECTIVE COATINGS
STEELS
TENSILE PROPERTIES
TRANSITION ELEMENT COMPOUNDS