In this paper the temperature distribution of welded plates under unstationary states is studied.
When the welding arc, whose voltage is V volt and current intensity I amp., starts from the origin and runs along the x-axis positive-wards which a constant velocity υ cm/sec, temperature rise θ°C of a point (x, y) is expressed by following equations,
(1) During Welding
θ=q/4πλe^{-υ/2x ξ} ………(a)
ξ=x-υt, α=a²+υ²/4, γ=α/4K(ξ²+y²)
(2) After Welding
θ=q/4πλ e^-υ/2Kωα(T+τ)Sxτ(γ) ………(b)
ω=x-υ(T+τ), α=α²+υ²/4_k, γ²=α/4_K(ω²+y²)
where
q: heat quantity given from the arc to the plate per unit time per unit thickness of the plate,
q=η×024⋅V⋅I⋅1 b
η=0.6-0.65
cal/cm/sec
b : the thickness of the plate, cm
t : time after the welding is commenced, sec
T : time interval of welding, sec
τ : time after the welding is finished, sec
λ : heat conductivity of the pate, cal/cm/sec/°C
k : thermal difusivity of the plate, cm²/sec
a²: coefficient of cooling α²=2E/c∂b 1/sec
E : heat loss from the surface of the plate per unit time, unit surface area and per unit temperature difference, cal/cm²/sec/°C
c : specific heat of the plate, cal/g/°C
ρ : density of the plate, g/cm³
and
n₂Sn₁(y)=∫e/ξ^-ξ-γ/ξdξ ………(c)
The value of nS₀(γ)=∫e/ξ^-ξ-γ/ξdξ is showed in Table 1. nS₀(γ) is already calculaced, when γ≤1. But as in practical problems we often need the value of it, when γ>1 so we added the table of nS₀(γ), when γ=1.10-35.0.

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