A Transient Thermal Model for Friction Stir Weld. Part II: Effects of Weld Conditions

Abstract

In Part II of this series of articles, the transient thermal model, which was introduced in Part I, is used to explore the effects of welding conditions on the heat generation and temperature. FSW of the 6061-T651 aluminum alloy is modeled to demonstrate the model. The following two steps are adopted to study the influence of welding conditions on the heat generation and temperature. First, the thermal model is used to compute the heat generation and temperature for different welding conditions, the calculated results are compared with the reported experimental temperature, and a good agreement is observed. Second, the analytical method is used to explore the approximate functions describing the effect of welding conditions on the heat generation and temperature. Based on the computed results, we discuss the relationship between the welding conditions, heat generation, temperature, and friction coefficient, and propose a relationship map between them for the first time at the end.

Nomenclature

D _p , D _s :

pin, shoulder diameter (mm)

E :

weld heat input (J/mm)

h _p :

pin length (mm)

K :

curve fitting slope

L :

characteristic length (mm)

M :

torque (Nm)

P :

pressure (Pa)

q :

heat generation rate (J mm⁻³)

Q _P , Q _s , Q _total :

pin, shoulder and total heat generation (W)

R _p , R _s :

pin, shoulder radius (mm)

r :

radius (mm)

T :

temperature (K)

T _melt :

melting point (K)

T _p :

temperature in pin/matrix interface (K)

$\overline{{T_{p} }}$ :

temperature (K), $T_{{p, { \max }}} < \overline{{T_{p} }} < T_{{p, { \min }}}$

T _s :

temperature in shoulder/matrix interface (K)

$\overline{{T_{s} }}$ :

temperature (K), $T_{{s, { \max }}} < \overline{{T_{s} }} < T_{{s, { \min }}}$

$T_{\text{center}}^{s}$ :

temperature at the SC (K)

$T_{\text{center}}^{p}$ :

temperature at the PC (K)

t _d :

dissolution time (s)

v :

advancing speed (mm min⁻¹)

x,y,z :

coordinate axes

β :

pin contact coefficient for treaded pin

μ ₀ :

curve fitting intercept

μ :

comprehensive friction coefficient

$\theta$ :

angle (rad)

$\omega$ :

rotation rate (rpm)

$\pi$ :

Pi