Single Welded Joints Research Articles

The Comparison between Mechanical Properties of Laser-Welded Ultra-High-Strength Austenitic and Martensitic Steels

The paper investigates experimentally the usability of ultra-high-strength stainless steel and abrasion resistant steel in laser-welded sandwich structures. The fatigue and shear strength of laser joints were investigated using lap joints that were welded using two very different energy inputs. Also the effect of multiple weld tracks was investigated. The properties of separate laser welds were characterized by hardness testing and optical microscopy. Results of the hardness measurements showed that there was softened area at heat-affected-zone and weld metal of the ultra-high-strength stainless steel welds. AR steels weld metal was harder than base metal and there was softened zone in heat-affected-zone of the weld. The shear strength of tested single weld joints of the ultra-high-strength stainless steel was higher compared abrasion resistant steel single weld joints, but stronger joint can be made with multiple weld seams for abrasion resistant steel. Fatigue strength of investigated ultra-high-strength stainless steel lap joint was lower than fatigue strength of abrasion resistant steel lap joint in the low-cycle regime, but there was no practical difference in fatigue limit (10e7 cycles).

Aumento de calidad en uniones soldadas de estructuras de paredes delgadas mediante modelo de simulación

El módulo de cálculo de simulación y el paquete de software solidworks han ayudado a definir la forma y las dimensiones óptimas de uniones soldadas simples que pueden servir de base para calcular los parámetros de proceso de soldadura. Habiendo comparado los modelos con diferentes secciones transversales de soldadura, el autor ha determinado que la altura y el ancho de la soldadura no afectan significativamente la concentración de tensión, y la concentración y el valor de la tensión dependen principalmente de la forma del latido de la raíz y del punto de separación entre las partes soldadas.

Simulation of the creep behaviour of P92 sandwich structures at 650°C with loading transverse to the intermediate layer

Abstract Improving thermal efficiency in modern steam turbines can be achieved by the application of new cooling systems, such as sandwich structures, which enable cooling steam to flow without severe losses during operation. In a preliminary investigation a cooling structure was developed which combines an interlayer of a woven wire mesh between two plane sheets. An exact knowledge of the mechanical behaviour, especially the creep behaviour, of the so called Grid Sheet structures, manufactured from the ferritic chromium steel P92, is essential for an adoption in a new built combined cycle power plant. In order to characterise and simulate the mechanical behaviour of the structures, creep tests with loading transverse to the intermediate layer were carried out and used as a reference for the simulated results. In this work the creep behaviour was simulated with the finite element method using creep law material parameters determined from bulk material. A model for a prediction of the point of time when single weld joints collapse was introduced.

Stress Intensity Factors of Semi-Elliptical Cracks in a Tubular Welded Joint Using Line Springs and 3D Finite Elements

Abstract A tubular welded T-joint containing a series of semi-elliptical cracks of increasing depth located near the chord-brace intersection, has been analyzed using shell elements with the cracks modeled by the line spring concept of Rice and Levy [1]. The same problem has also been modeled with 20-noded bricks allowing the stress intensity factors to be determined by virtual crack extension. The direction of crack growth has been determined both using off-axis virtual crack extension and solutions for kinked cracks, to determine the orientation which maximize either the strain energy release rate G or KI. The calculated crack path agrees with reported experiments [2]. Finally, the stress intensity factors for straight and curved cracks in single welded joints have been compared in terms of their effective depth.