ESTABLISHMENT OF THE MECHANICAL
CHARACTERISTICS OF THE DEPOSITED METAL
* Tensile strength: Rm * Resilience........... : K
* Yield point 0,2% : Rp (0,2) * Toughness........... : H
* Elongation: A
1. TENSILE STRENGTH, YIELD POINT AND ELONGATION
TENSILE STRENGTH TEST OF THE STEEL (NF A 03-151)
This test involves subjecting a test-tube to a tensile strength until it breaks in order to determine the mechanical characteristics of the metal.
TENSILE STRENGTH TEST PREMISES
The tube that is subject to an increasing and rectangular stress extends uniformly (elastic elongation) until a certain characteristic value. This value is the tensile strength. If that stress was stopped at that point, the tube would recover its original dimensions. However, if the stress gets harder, the elongation of the tube will be faster and more pronounced until the elongation becomes permanent and the tube breaks.
This test allows us to define three important features of all metals:
* Tensile strength Rm
* Yield point:: Rp 0,2
* Elongation: A %
TENSILE BREAKING STRESS OR TENSILE STRENGTH
It is the value that shows how resistant a material is to a tensile strength:
Rm (Mpa) = F (N) / S (mm2)
This value explains how difficultly or easily a material can elongate:
Rp0,2 (Mpa) = F (N) / S (mm2)
Difference between the original dimensions of the test-tube and its dimensions after breaking. Value expressed in %.
|Rm||Kg/mm2||Mpa||1 Mpa = 1 N/mm2 = 0,102 Kg/mm2|
|Rp 0,2||Kg/mm2||Mpa||1 Mpa = 1 N/mm2 = 0,102 Kg/mm2|
Mpa = Mega pascal
N = Newton
2. RESILIENCE TEST (NF A 03-156)
This test allows us to check how resistante to fatigue a material is.
Resilience= energy absorved during the break (joules) / Surface S0 (cm2)
|KCU||Resilience (U notch)|
|KCV||Charpy resilience (V notch)||Used at temperatures lower than 0ºC|
|KCU||Kg/cm2||daJ/cm2||1 daJ/cm2 = 1,02 Kg/cm2|
|KCV||Kg/cm2||daJ/cm2||1 daJ/cm2 = 1,02 Kg/cm2|
1 daJ = 10 Julios
3. TOUGHNESS TEST
The toughness of a material is seen in its resistance to being penetrated by a tough object. There is a relation between the tensile strength of a metal (Rm) and its toughness.
DIFFERENT TOUGHNESS TESTS
- Brinell test (HB) (NF A 03-152). Penetrator: hard steel ball.
- Rocknell test (HR) (NF A 03-153) HRB. Penetrator: hard steel ball HCR, diamond cone (more usual).
- Vickers test (HV) (NF A 03-154) HV. Penetrator: conic based diamond pyramid
CORRESPONDENCE OF THE MAIN TOUGHNESS UNITS
CORRESPONDENCIA DE LAS PRINCIPALES MEDIDAS DE DUREZA
|Según la Euronorma 8.55.|