A lead—free solder wire includes a core wire with a first alloy and a shell coating layer with a second alloy. The first alloy may be composed of Bi—Ag, Bi—Cu, Bi—Ag—Cu, or Bi—Sb; and the second alloy may be composed of Sn, In Sn—Ag, Sn—Cu, Sn—Ag—Cu, Sn—Zn, Bi—Sn, Sn—In, Sn—Sb or Bi—In, such that the shell coating layer is applied to a surface of the core wire. In another implementation, the lead free solder wire may include a first wire with a first alloy and a second wire with a second alloy. The first alloy may be composed of Bi—Ag, Bi—Cu, Bi—Ag—Cu, or Bi—Sb; and the second alloy may be composed of Sn, Sn—Ag, Sn—Cu, Sn—Ag—Cu, Sn—Zn, Bi—Sn, Sn—In, Sn—Sb or Bi—In, such that the first alloy of the first wire and the second alloy of the second wire are braided together.

The present invention provides a flux-cored welding wire comprising a shell having a tubular cavity, which accommodates flux. The shell is made of 400 series stainless steels. The deposited metal formed after the welding using the flux-cored welding wire of the present invention has more uniform chemical compositions. Because the loss of chromium during the transition to the deposited metal is less than 0.1%, recourses is saved and welding cost is reduced. The filling ratio of the flux-cored welding wire of the present invention is 5%-25% (preferably 10%-20%). As a result, not only the stability of the compositions in the flux is increased, but also the disadvantages to the manufacture process caused by high filling ratio are avoided. The flux-cored welding wire of the present invention will not be rusty even after it is exposed to the air for a long time.

The present disclosure relates generally to an improved design of a metal-cored welding wire electrode for use on a high deposition rate welding process that resistively preheats the wire prior to being subjected to the welding current. The preheat circuit reduces the welding current drawn by the electrode so that higher wire feed speeds, and thus higher deposition rates, may be obtained. The metal-cored welding wire includes both a higher fill rate (a greater percentage of the welding wire is the granular core) along with added sulfur and an added bead wetting agent. The bead wetting agent may be one or more of selenium, tellurium, arsenic, gallium, bismuth, and tin. The improved metal-cored welding wire leads to an enhanced weld deposit appearance that means the weld deposits are less likely to be rejected as unusable.

Provided is a welding method using a special torch and a flux cored wire, in which the special torch has a suction nozzle between the contact tip and the shield nozzle, and the flux cored wire has a flux filled inside the steel outer casing, and a seam portion where both ends of a metal in a width direction of the steel outer casing are butted or overlapped in a longitudinal direction of the flux cored wire.

Fixed-cutter matrix bits comprising hardfaced elements on the gauge pads, and methods of manufacture and using. An example fixed-cutter matrix bit comprises a matrix bit body, a plurality of cutter elements secured at fixed locations to the matrix bit body, and a plurality of gauge pads disposed on the matrix bit body; wherein at least one of the gauge pads includes a hardfaced exterior surface. The hardfaced exterior surface may comprise a material selected from the group consisting of tungsten, niobium, vanadium, molybdenum, silicon, titanium, tantalum, zirconium, chromium, yttrium, boron, carbon, carbides thereof, nitrides thereof, borides thereof, oxides thereof, silicides thereof, and combinations thereof. The hardfaced exterior surface may be fused to the at least one gauge pad during the infiltration process of manufacturing the matrix bit body.

A flux core wire for a welding method, having a tubular wire sheath, a wire core of flux powder, which is surrounded by the tubular wire sheath, wherein the wire sheath and the wire core have a composition such that during the welding a melt of CuSn.sub.12Ni.sub.2 materialises.

A flux according to the present invention contains a rosin methyl ester in which the flux is a solid or solid-like flux at 25° C., and is used for an inside of a flux-cored solder or an exterior of a flux-coated solder.

The present invention relates to a flux-cored wire which can be used for straight-polarity gas-shielded arc welding, wherein a flux contains one or several types of metal compound powders and, when one or several metal elements constituting the metal compound powders are formed into stable compounds under a high-temperature environment, the relationship between the weighted geometric mean value (Φ) of the work functions of the stable compounds and the wire diameter (D) of the flux-cored wire satisfies the following formula: {1.00≤Φ≤−0.0908D.sup.2+0.5473D+1.547}.

A flux-cored wire for arc welding, including a steel sheath filled with flux, where the wire contains, relative to a total mass of the wire, Cr: 16.0 to 22.0 mass %, Ni: 6.0 to 11.0 mass %, Mn: 0.7 to 2.6 mass %, Si: 0.1 to 1.1 mass %, Zr: 0.2 to 0.8 mass %, Fe: 45.0 to 65.0 mass %, TiO.sub.2: 5.0 to 9.0 mass %, SiO.sub.2: 0.1 to 2.0 mass %, ZrO.sub.2: 0.5 to 3.0 mass %, and Bi: less than 0.0020 mass %. Where by mass %, a Si content is denoted by [Si] and a Zr content is denoted by [Zr], a value of parameter A expressed by A=[Si]+2×[Zr] satisfies 1.4 to 2.5.

An arc welding method includes welding a steel sheet while alternately switching feeding of a welding wire between forward feeding and backward feeding. The welding wire contains, in mass % with respect to a total mass to the welding wire, C: more than 0 and 0.30 or less, Si: 0.01 to 0.30, Mn: 0.5 to 2.5, S: 0.001 to 0.020, Ti: 0.05 to 0.30, and optional elements with the remainder being Fe and unavoidable impurities, and a value obtained by 2×[Ti]/[Si]−50×[S] is more than 1.0. The welding is performed by using a shielding gas containing CO.sub.2 gas in an amount of 80 vol. % or more with respect to a total volume of the shielding gas at a frequency of 40 Hz or more and 200 Hz or less, where one cycle for determining the frequency is one forward feeding and one backward feeding.