Heating of a Metal Layer by a Scanning Laser Beam

APPENDIXThermal-Physical Copper Parameters

Here, we give values of parameters and coefficients in the dependences of thermal physical characteristics on temperature T, given in Kelvin, and their modification for the relative temperature θ = T/Twork in two operating ranges, Twork = 293 K and Twork = 1300 K < Tmelt = 1356.55 K, based on data [2124]

Copper density: ρ0 = 8890 [kg m–3],

ρ1 = 0.362 [kg m–3 K–1],

ρ(T) = 8890 – (8890 – 8680)(T – Tn)/(600 – 20) for Tn = 293 K, ρ(T) = ρ0 + ρ1(T – Tn) = ρ0[1 + \(\rho _^}\)(θ – θп)], \(\rho _^}\) = 0.012 (0.0529) for Twork = 293 (1300) K.

Heat capacity: cp = 0.381 [kJ/(kg K)],

\(c_}^}\) = 1.419 × 10–4 [kJ/(kg K2)],

\(_}}\)(T) = 0.374 + (0.414 – 0.374)(T – Tn)/(573 – 293),

\(_}}\) = cp/1.02 = 0.374 [kJ/(kg K)],

\(_}}\)(T) = \(_}}\) + \(c_}^}\)(T – Tn) = \(_}}\)[1 + \(c_^}\)(θ – θп)],

\(c_^}\) = 0.1115.

Thermal conductivity coefficient:

κ(T) = k(θ) = κ0–κ1T + κ2T2 – κ3T3,

ki = (–1)iκi\(T_}}}^\), [kj] = W m–1 K–1, κ0 = 427,

κ1 = 0.147, κ2 = 1.14 × 10–4, κ3 = 4.7 × 10–8,

[κj] = W m–1 K–(j+1), k(θ) = κ0(1 + k1θ + k2θ2 + k3θ3),

k1 = –0.101, k2 = 0.0229, k3 = –0.00276 for Twork = 293 K and k1 = –0.448, k2 = 0.4508,

k3 = –0.241 for Twork = 1300 K.

Convective (Newtonian) heat transfer:

Heat transfer with gas,

αg(T) = h0– h1T + h2T2 – h3T3,

[\(_}}_}\)] = Jm–3 K–1, h0 = 0, h1 = 0.003, h2 = 10–6,

h3 = 10–9, [hj] = W m–2 K–(j+1), [CN] = W m–2 K–1,

cN(T) = 1 + c1θ + c2θ2 + c3θ3, c1 = –0.11,

c2 = 0.0107, c3 = –0.00314 for Twork = 293 K, and c1 = –0.488, c2 = 0.0475, c3 = –0.0139 for Twork = 1300 K. cN(Tamb = 293 K) = 0.898.

Heat exchange with a steel substrate

αsub = \(_}\;}}}}_}}}}\) = const, CFe = 30 [W m–2 K–1].

Radiation heat transfer:

αR = 4.54 × 10–8 [W m–2 K–4], βR = 0.143.

Absorption coefficient:

1 – R(T) = B0b(θ) = B0 + B1T + B2T2, B0 = 0.028, B1 = 1.5 × 10–5, |B2| < 10-8,

[Bj] = K–j, b(θ) = 1 + b1(θ) + b2(θ)2, b1 = 0.157,

|b2| < 0.031.

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