Fracture Mechanics

8.1 Introduction and Synopsis The development and production of High Strength Low Alloy (HSLA) linepipe steels has been growing rapidly because of their desirable combination of high strength, low temperature toughness, weldablity and low cost. With the advent of the welding as the major method of fabrication, cracking in the heat affected zone has become […]

Implications of real-time CWM

If our prediction that CWM can be done in real-time is correct then CWM is likely to be used routinely in industry. This raises the question of what will be the impact of routine use of CWM in industry. We believe this will dramatically change both engineering and research in the three main components of […]

Real-Time for CWM

Is real-time Computational Welding Mechanics feasible? For the question to have meaning, it is necessary to first specify what we mean by a solution and what errors in the solution are tolerable. We define a solution to be the transient temperature, displacement, strain and stress and microstructure evolution evaluated at each point in space and […]

Analysis of a Weld Structure

Figure 6-5, chapter VI, shows a composite mesh for a weld on a pressure vessel. These meshes do not always conform; i. e., nodes and element faces on either side of the interface need not match. Continuity of temperature or displacement fields across the interface can be maintained by constraints. These constraints are imposed automatically […]

Weld Joint

A weld joint usually joins two or more parts. In any case we assume that the position of any weld joint in space can be associated with a curve in 3D space. This curve is parameterized by distance and hence has a start and stop point. At each point on this curve, a tangent vector […]

Weld Procedure

A weld procedure is a specification for a weld joint defined on a cross-section of the weld joint. It specifies the number of weld passes, the position and shape of the nugget for each pass and the details of the weld process for each pass. The details include the type of weld process, type and […]

Welded Structures and Applications of Welding in Industrial Fields

7.1 Introduction and Synopsis A welded structure is usually designed by a structural engineer who designs the structure but only specifies the requirements of the welded joints. A welding engineer, not the structural engineer, specifies the weld procedure for each joint to meet the requirements specified by the structural engineer. Next a production engineer specifies […]

Computational Analysis

By 3D-FEM analysis for hydrogen diffusion, the heat transfer, stress-strain analysis and transient microstructure distribution must be coupled. This FEM formulation leads to asymmetric equations. Other than that the formulation is straight forward. The value of temperature at the nodes is obtained by solving the associated energy problem. The microstructure is evaluated at the nodes […]

Preheat prediction

Several investigators have developed relationships for predicting preheat levels to avoid the HAZ hydrogen cracking problem. Bibby et al [28] present a review of the predictive methods to assist in managing hydrogen in welding applications. The following method may be used to determine the necessary preheat temperature for steel welding. This method is based on […]

Hydrogen Diffusion in Welds

Hydrogen cracking is an important cause of failures in many welded structures. Given a sufficiently sensitive microstructure, a sufficient hydrogen concentration and a high enough tensile stress state, hydrogen cracking, sometimes called cold cracking, is likely to occur. Hydrogen cracking usually involves delays of minutes to years. If cellulosic electrodes are used, it is usual […]