test 2 make sure you understand

Question 1

Brittle fracture

Answer 1

Fracture that occurs by rapid crack propagation and without appreciable macroscopic deformation.

Question 2

Corrosion fatigue

Answer 2

A type of failure that results from the simultaneous action of a cyclic stress and chemical attack.

Question 3

creep:

Answer 3

The time-dependent permanent deformation that occurs under stress; for most materials it is important only at elevated temperatures.

Question 4

ductile fracture:

Answer 4

A mode of fracture attended by extensive gross plastic deformation.

Question 5

ductile-to-brittle transition:

Answer 5

The transition from ductile to brittle behavior with a decrease in temperature exhibited by some low-strength steel (BCC) alloys; the temperature range over which the transition occurs is determined by Charpy and Izod impact tests.

Question 6

fatigue:

Answer 6

Failure, at relatively low stress levels, of structures that are subjected to fluctuating and cyclic stresses.

Question 7

fatigue life (Nf):

Answer 7

The total number of stress cycles that cause a fatigue failure at some specified stress amplitude.

Question 8

fatigue limit:

Answer 8

For fatigue, the maximum stress amplitude level below which a material can endure an essentially infinite number of stress cycles and not fail.

Question 9

fatigue strength:

Answer 9

The maximum stress level that a material can sustain without failing, for some specified number of cycles.

Question 10

fracture toughness (Kc):

Answer 10

The measure of a material’s resistance to fracture when a crack is present.

Question 11

impact energy (notch toughness):

Answer 11

A measure of the energy absorbed during the fracture of a specimen of standard dimensions and geometry when subjected to very rapid (impact) loading. Charpy and Izod impact tests are used to measure this parameter, which is important in assessing the ductile-to-brittle transition behavior of a material.

Question 12

intergranular fracture:

Answer 12

Fracture of polycrystalline materials by crack propagation along grain boundaries.

Question 13

stress raiser:

Answer 13

A small flaw (internal or surface) or a structural discontinuity at which an applied tensile stress will be amplified and from which cracks may propagate.

Question 14

thermal fatigue:

Answer 14

A type of fatigue failure in which the cyclic stresses are introduced by fluctuating thermal stresses.

Question 15

transgranular fracture:

Answer 15

Fracture of polycrystalline materials by crack propagation through the grains.