Crack determination

Made by Voronova O.Y.

Scientific supervisor – Volchuc V.N.

Language supervisor – Kuznecova E.S.

Crack

Can be defined as an extreme defect, being a region with completely broken atomic bonds (bank of cracks) and partly broken atomic bonds (crack tip).

Fracture

Ductile fracture Brittle fracture

General Information

-Experimental determination

 of crack

-structural features

-specimen “compact” model

-stress intensity

Fragility is not a property

The influence of structural features

O brittle fractures;O larger grains of ferrite;O distribution of cementite (Fe3C);O impurities effect.

The effect of additives

-oxygen,nitrogen,phosphoru

s,

sulfur,silicon

-vanadium,cobalt ,chromium

-manganese,copper,nickel

Standard sample

Parameter of fracture toughness -is a property of material characterizes its viscosity or ability to slow down the destruction

Stress intensity

   - characteristic of fracture

toughness in plane deformation (MP

a × m1/2);B - specimen thickness (mm);

W - width of specimen (mm);

P - cycle loading;a - initial crack length (mm).

(29.6(-185.5(+655.7(-1017()

Thank you for your attention!