PSI - Issue 36

Olexandr Ivanov et al. / Procedia Structural Integrity 36 (2022) 223–230 Olexandr Ivanov et al. / Structural Integrity Procedia 00 (2021) 000 – 000

226

4

Fig. 2. Scheme of modeling the process of heat propagation during hardfacing.

After theoretical calculations and experimental measurement of the kinetics of temperature change during surfacing, a comparison of these values was performed. Investigation of microstructure was observed with a scanning electron microscopy (SEM) using ZeiSS EVO 40XVP electron microscope. The hardness measurement was observed by means of the average measurements taken from the top surface of the harfacing by Rockwell method, scale “C”. Wear testing with non -fixed abrasion was carried out according to ASTM G65 standard. 3. Results and discussion As was mentioned before, the process of wear-resistant hardfacing can be approximated in the form of a scheme of surfacing of the roller nearby to the edge of the solid plate. Taking into account the equation for a moving heat source on the surface of a semi-infinite body, it was assumed that the heat saturation process from the heated region also ended and the temperature of the points in it stabilized. As a result, a temperature field with constant parameters is formed around the heat source, which moves together with the source. Thus, there is a limit state of heat distribution in the body, in which the heat transfer to the environment is equal in magnitude to the inflow of heat from the source. In this state, the temperature field moving together with the coordinate system (x, y, z) is constant and is called quasi-stationary. The equation for determining the temperature at any point A, taking into account the action of a fictitious source takes the form:

 exp( 1

1

q

v x

 v R

 a v R 2

  

  

 

  

   

  

 +  

  

  

( , , , )

exp

)

exp(

)

T x y z

 =



−

−



−

1

2

(1)

2

2

2

a R

a

R

 

 

1

2

where q is the effective thermal power J (q = IU); λ – thermal conductivity, W/m·°C; v – deposition rate, m/h; l – distance from the edge of the body; a – coefficient of thermal conductivity, m 2 /s.

2 2 1 R x y z = + +

2

(2)

2 ) (2 l y z R x = + − + 2

2

(3)

2



,

a

=

(4)

c



where c is the specific heat, J/g·K; ρ – density, g/cm 3 . The specific heat can be expressed through the Gibbs