A method and apparatus for welding include initiating a pulse welding process includes initiating a welding arc by providing CC type welding power, maintaining the arc by providing CV type power. Then, pulse type welding power is provided. The method and system can be used to start short circuit, or other welding processes by providing short circuit power, or welding power of a given mode, instead of providing pulse power. Also, in one alternative, a method and system of initiating a pulse, short circuit, or given welding process includes initiating a welding arc by providing CC type welding power at least until a pseudo-equilibrium for the arc is established. Then, providing welding power in a pulse, short circuit, or the given mode.

Method and apparatus for welding

Disclosed is a hardfacing alloy capable of withstanding service abrasion of the order of silicious earth particles and weldable on industrial products, such as tool joints and stabilizers used in oil and gas well drilling, and other industrial products. The hardfacing alloy has a low coefficient of friction resulting from excellent metal to metal resistance and significant reduction in industrial wear on industrial products, such as casing wear. Other embodiments of the invention include tool joints having the hardbanding alloy welded to the outer cylindrical surface to its box and pin members and to stabilizer ribs on the stabilizer used in earth boring, such as boring for oil and gas, other industrial products, and methods of applying the hardfacing alloy to their surfaces. The hardfacing alloy does not require any post weld treatment, has primary borides in its microstructure, the carbons in the alloy are tied up in the formation of secondary carbides which add to the abrasion resistance, and have a quadratic crystallographic structure and a hardness of about 1725 Hv comparable to the prior art hardness of the chromium carbide primary carbide alloys of the prior art but is substantially less brittle than C—Cr—Fe hardfacing alloys.

Hardfacing alloy, methods and products

The porosity formation in cold metal transfer (CMT) gas metal arc welding (GMAW) of zinc coated steel is studied over a wide range of the heat inputs (160–250 J mm− 1), which shows low porosity in weld bead (  350 J mm− 1) heat inputs and maximum at medium (250–350 J mm− 1) heat inputs. The high speed imaging of weld pool shows that the highest frequency of zinc vapour escapes at high heat inputs compared to other conditions. Numerous experiments show that size and location of pores along with escaping of zinc vapour are the results of competition of viscosity of weld pool against buoyancy and vapour pressure within the time required to reach solidification temperature. Based on this concept, mechanisms involved in porosity formation, growth and escape phenomena are disclosed, which can help select the optimised welding conditions to obtain porosity free welds in CMT-GMAW of zinc coated steels.

Porosity formation mechanisms in cold metal transfer (CMT) gas metal arc welding (GMAW) of zinc coated steels

The invention relates generally to welding and, more specifically, to welding wires for arc welding, such as Gas Metal Arc Welding (GMAW) or Flux Core Arc Welding (FCAW). In one embodiment, a tubular welding wire includes a sheath and a core. Further, the core includes a carbon source and an agglomerate having a Group I or Group II compound, silicon dioxide, and titanium dioxide. Additionally, the carbon source and the agglomerate together comprise less than 10% of the core by weight.

Systems and methods for welding electrodes

Provided is a welding system and method for controlling a welding system with an improved waveform. In accordance with one aspect of the present invention, a welding system waveform is calibrated such that the welding transfer regularly occurs during short circuits, comprising applying a voltage and a current to a welding electrode, applying an increased voltage and an increased current to the welding electrode, increasing the current to the welding electrode when a short circuit is detected, and maintaining the increased current applied to the welding electrode until a desired time expires after the short circuit is detected or until the short circuit clears, whichever occurs first.

Welding system and method with improved waveform

A metal-core weld wire usable for gas shielded arc welding gapless joints on low carbon and low alloy galvanized and galvanealed steels. The metal-core weld wire includes a low carbon steel sheath surrounding a core composition. In one embodiment, the low carbon steel sheath includes, by total weight of the metal-core weld wire, between approximately 0.01-0.03% C, and the core composition includes, by total weight of the metal-core weld wire, between approximately 0.05-0.20% Ti, between approximately 0.05-1.00% Nb, Fe powder, and Mn to the extent that the metal-core weld wire includes between approximately 0.1-1.0% Mn wherein the metal-core weld wire includes between approximately 0.1-1.0% Si. The core composition is, by total weight of the metal-core weld wire, between approximately 0.001-12.0%. The metal-core weld wire provides, at weld rates up to 150 cm/min, reduced arc ionization potential and spatter, and improved arc stability and shielding. The metal-core weld wire produces, at weld rates up to 150 cm/min, weld deposits having reduced blow holes and porosity, no liquid metal embrittlement, and reduced weld pool surface tension resulting in an improved wetting characteristic.

Metal-core weld wire for welding galvanized steels

An improved metal-core weld wire, usable for joint and surface welding, having a steel sheath with a core, and a core composition disposed in the core of the steel sheath, wherein the core composition is between approximately 0.001-12.0% total weight of the metal-core wire. The metal-core wires of the present invention have improved manufacturability. In another embodiment, the core composition includes iron powder in an amount that provides an oxygen content less than approximately 600 ppm in the metal-core wire for producing weld deposits with improved impact strength properties.

Metal-core weld wire with reduced core fill percentage

PROBLEM TO BE SOLVED: To apply a metal-cored welding wire to a gapless joint of gas shielded arc welding for low carbon low alloy galvanized steel and galvaannealed steel. SOLUTION: A metal-cored welding wire is provided with a low carbon steel sheath around the composition of the core. The sheath contains 0.01-0.03% C in the total weight of the welding wire, with the core component containing 0.05-0.20% Ti and 0.05-1.00% Nb and Fe powder, and with the welding wire containing 0.1-1.0% Mn and 0.1-1.0% Si. The core component is 0.001-12.0% in the total weight of the metal-cored welding wire. This welding wire lowers ionization potential and spatter at the welding speed of 150cm/min, enhances arc stability and arc shield, decreases blow holes and porosity, eliminates liquid metal brittleness, improves wettability, and provides a weld deposition with a reduced weld puddle surface tension.

Roger A. Daemen

Papers

Metal-core weld wire for welding galvanized steels

Metal-core weld wire with reduced core fill percentage

Metal cored welding wire for galvanized steel and galvaannealed steel