Butt welding

About: Butt welding is a research topic. Over the lifetime, 7153 publications have been published within this topic receiving 44467 citations.

Analysis of pulsed Nd:YAG laser welding of AISI 304 steel

Abstract: Pulsed laser welding of AISI 304 stainless steel plate was simulated using commercial finite element software to determine the optimal welding conditions. Due to geometric symmetry, only one plate was modeled to reduce the simulation computation time. User subroutines were created to account for a moving three-dimensional heat source and to apply boundary conditions. The material properties such as conductivity, specific heat, and mass density were determined as functions of temperature. The latent heat was considered within the given temperature range. The three-dimensional heat source model for pulsed laser beam butt welding was designed by comparing the finite element analysis results and experimental data. This successful simulation of pulsed Nd:YAG laser welding for AISI 304 stainless steel will prove useful for determining optimal welding conditions.

Friction Stir Welding of HSLA-65 Steel: Part II. The Influence of Weld Speed and Tool Material on the Residual Stress Distribution and Tool Wear

Abstract: A set of single pass full penetration friction stir bead-on-plate and butt welds in HSLA-65 steel were produced using a range of traverse speeds (50 to 500 mm/min) and two tool materials (W-Re and PCBN). Part I described the influence of process and tool parameters on the microstructure in the weld region. This article focuses on the influence of these parameters on residual stress, but the presence of retained austenite evident in the diffraction pattern and X-ray tomographic investigations of tool material depositions are also discussed. The residual stress measurements were made using white beam synchrotron X-ray diffraction (SXRD). The residual stresses are affected by the traverse speed as well as the weld tool material. While the peak residual stress at the tool shoulders remained largely unchanged (approximately equal to the nominal yield stress (450 MPa)) irrespective of weld speed or tool type, for the W-Re welds, the width of the tensile section of the residual stress profile decreased with increasing traverse speed (thus decreasing line energy). The effect of increasing traverse speed on the width of the tensile zone was much less pronounced for the PCBN tool material.

Fabrication and Engineering Technology for Lightweight Ship Structures, Part 1: Distortions and Residual Stresses in Panel Fabrication

Abstract: An increase in shipboard applications of lightweight structures has been evident over the recent years in both military and commercial vessels. Ship panel distortions generated through various stages of production (e.g., material handling, blast and paint, panel fabrication, subassembly, assembly, outfitting, and erection) have emerged as a major obstacle to the cost-effective fabrication of these lightweight structures. This problem is particularly challenging for naval ships that are built with relatively thin plate and require fair surfaces to maximize hydrodynamic performance and minimize radar signature. With a recent major initiative funded by the U.S. Navy, a comprehensive assessment of the lightweight panel fabrication technology has been undertaken. This assessment took into account the residual stresses of thin plate conditions during the material handling, cutting, fitting, and welding processes. A series of test panels with varying degrees of complexity representing the typical shipboard applications were designed and used to quantify dimensional variations through the entire fabrication processes in a production environment. A light detection and ranging (LIDAR) measurement system was used to analyze panel distortion topography resulting from different processes. Welding attributes, stiffener assembly sequence, and material handling methods were systematically monitored and evaluated to identify areas for fabrication improvement. Advanced computational tools were further developed and used to establish the underlying distortion mechanisms and critical process parameters in these panel structures. Some of the major findings include the following: (1) local buckling is the dominant distortion mechanisms in lightweight panel structures; (2) special care must be exercised in material handling of lightweight structures in preventing long-range permanent deformation; (3) dimensional accuracy from thermal cutting can have a significant impact on buckling distortions, particularly for different thickness combinations in complex panels; (4) any effective mitigation techniques for minimizing buckling distortion should either reduce the buckling driving force (fabrication induced stresses) and/or increase the buckling resistance (e.g., panel geometric parameters and assembly procedures); (5) butt welding of plates to make panels requires a low heat input narrow groove process to minimize distortion prior to fillet welding of stiffeners; (6) precision fillet welding process with automatic seam tracking offers the potential to minimize overwelding.