WELDING RESEARCH NOVEMBER 2016 / WELDING JOURNAL 433-s A B C D creepperformance of the welded furnace roll. The results of the following study were reported in Ref. 22 in which both flux-cored arc welding (FCAW) and EBW were modeled to predict residual stress by inputting the detailed welding information, such as welding parameters and number of weld passes. The same conclusion that EBW without filler metal is an effective method to improve creep-fatigue life was obtained when including weld residual stress. Analysis Procedure Finite Element Model A new design (Fig. 2A) of the furnace roll in the continuous hot-dip coating line was developed and consisted of two journals made of stainless steel 310 (SS310), two end bells made of high-temperature alloys MO-RE®1, and a roll shell made of MO-RE®1. There were two weld types in the roll: the shell weld joining the end bell to the shell and the journal weld joining the journal to the end bell. Because of loading and geometric symmetry, a half three-dimensional (3D) finite element model was used in the analysis and symmetric boundary conditions were applied in the symmetric plane, as shown in Fig. 2B. Heat Transfer Analysis The heat transfer analysis was governed by the following equation: The heat transfer analysis was governed by the following equation: where (T) is the density of material, cp(T) is the specific heat, Kx(T), Ky(T), Kz(T) are the thermal conductivity coefficients for three space directions, T is the temperature, and t is the time elapsed. In the analysis, thermal conductivity was assumed to be the same in all three space directions. Temperature-dependent material properties were included in the finite element model for material stainless steel 310 (Refs. 23, 24), MO-RE1 (Ref. 25), and N117 (Ref. 26). Figure 3A shows that the filler metal has the highest elastic modulus and MO-RE®1 has the lowest elastic modulus among the three materials. Figure 3B shows that N117 has the lowest coefficient of thermal expansion (CTE) among the three materials. Figures 3C–E show comparisons of yield strength, tensile strength, and elongation between the three materials at different tempera- (T)cp (T)T t = x Kx (T)T x + y Ky (T)T y + z Kz (T)T z (1) Fig. 3 — Comparison of material properties between three materials: A — Elastic modulus; B — coefficient of thermal expansion; C — yield strength; D — tensile strength; E — elongation. E
Welding Journal | November 2016
To see the actual publication please follow the link above