Effect of the mechanical properties and mode loading on the mechanical behaviour of weldment: a numerical analysis

Abstract

Welding is used to realize permanent assembly in mechanical structures to assure the continuity of the parts to be assembled contrary to the other assembly techniques which have physical or chemical discontinuities. Generally, crack evolution depends on several intrinsic and extrinsic parameters of material. The aim of this work is to analyse the severity of crack defects on the mechanical behaviour of Welded joints. The cracks are considered located in the weld metal. The J-integral method was used to analyse the fracture behaviour of these structures by the two-dimensional finite element method using Cast3M code. The effect of the mechanical properties, the mismatching and the crack size on the J-integral values was highlighted. A good correlation between the FEM simulations and the literature analysis results was observed. We note that the loading mode affects directly the J-integral value and consequently on the mechanical behaviour of the weldment.

Effect of the Heat Input and Ageing Treatment on Microstructure and Mechanical Properties of AISI 317L Stainless Steel Dissimilar Welded Joints

“…From the quantitative analysis showed in Table 6, it is also possible to infer that the welded joint using heat input of 8 kJ/cm and AHT time of 100 hours was the most critical condition due to its greater amount of deleterious phases. According to the literature 40 , the precipitation of 𝜎 and 𝜒 phases is prone to reduce the toughness and elongation of duplex stainless steels.…”

“…In fact, all tensile samples failed in the HAZ and HAZ/FZ transition region in the ductile mode. It is known that during the thermal cycles arising from the welding process, the HAZ changes chemically, physically and metallurgically, which consequently deteriorates the microstructure and mechanical properties of the material 40 .…”

“…This behaviour may be mainly attributed to the lower concentration of δ-ferrite in the HAZ of the welded joints with 4 KJ/cm compared with the welded joint using 8 KJ/cm (see Figures 1 and 2). According to several works [38][39][40][41] , higher percentage of the δ-ferrite in the HAZ significantly facilitates the hydrogen-induced embrittlement, being this hard phase the preferential path for cracks propagation.…”

“…This is may be related to the increase in the precipitation of the 𝜎 phase with the increase of the AHT time. In several cases, the greater precipitation of this phase affects the welded joint's tensile strength and hardnesst due to the dispersion of hard 𝜎 phase particles into the ferrite and/or austenite grains 40,42,43 . However, it is worthwhile mentioning that the tensile properties results indicate that even though the precipitation of 𝜎 phase increases with the AHT time, its volume fraction is not enough to produce a significant loss of ductility.…”

Effect of Tool Design on the Mechanical Properties of Bobbin Friction Stir Welded High-Density Polyethylene Sheets: Experimental Study

“…The aim of these tests is to evaluate weld resistance by looking at the hardness in the Nugget, TMAZ and HAZ zones and in the base material that is not affected by the process, particularly the hardness in and around the heat-affected zone. Most welding studies [37][38][39][40][41][42][43] focus on this region. The knowledge of his behavior may help us to evaluate the fragility of the weld and to determine if it has the required strength.…”