A steel sheet for the manufacture of a press hardened part is provided, having a composition of: 0.15%≤C≤0.22%, 3.5%≤Mn<4.2%, 0.001%≤Si≤1.5%, 0.020%≤Al≤0.9%, 0.001%≤Cr≤1%, 0.001%≤Mo≤0.3%, 0.001%≤Ti≤0.040%, 0.0003%≤B≤0.004%, 0.001%≤Nb≤0.060%, 0.001%≤N≤0.009%, 0.0005%≤S≤0.003%, 0.001%≤P≤0.020%. A microstructure has less than 50% ferrite, 1% to 20% retained austenite, cementite, such that the surface density of cementite particles larger than 60 nm is lower than 10{circumflex over ( )}7/mm.sup.2, and a complement of bainite and/or martensite, the retained austenite having an average Mn content of at least 1.1*Mn %. Press-hardened steel part obtained by hot forming the steel sheet, and manufacturing methods thereof.

Disclosed herein are embodiments of a powder feedstock, such as for bulk welding, which can produce welds. The powder feedstock can include high levels of boron, and may be improved over previously used cored wires. Coatings can be formed from the powder feedstock which may have high hardness in certain embodiments, and low mass loss under ASTM standards.

An arc welding method includes performing welding by using a gas and a solid wire. The gas contains Ar. The solid wire includes a steel core wire and a copper plating film formed on a surface of the steel core wire, and the copper plating film has an average grain diameter of 600 nm or less.

The present invention relates to a flux-cored wire for positive polarity gas-shielded arc welding use, in which a flux contains a metal powder and also contains BaF.sub.2 and SrF.sub.2 and AlF.sub.3 and/or CaF.sub.2 as fluorides wherein the content of BaF.sub.2 is 1.0 to 4.5%, the content of SrF.sub.2 is 2.0% or less, the content of CaF.sub.2 is 0.45% or less and the content of AlF.sub.3 is 0.70% or less, at least one of metal elements constituting the flux and the fluorides is a strong deoxidizing metal element having a specified standard formation Gibbs energy, and the content of each of an oxide and a carbonate in the flux is 0.5% or less.

The present disclosure relates to a method for producing a tubular welding electrode comprising the steps of providing a strip of metal material having a length and first and second surfaces, wherein at least the first surface of the strip is at least substantially coated with nickel or a nickel alloy and then copper or a copper alloy, forming the strip into a “U” shape along the length, filling the “U” shape of the strip with a granular powder flux, and mechanically closing the “U” shape to form a sheath of nickel- and copper-coated metal material that substantially encases the granular powder flux, thus forming a tubular welding electrode. In certain embodiments, the metal material may be steel. In certain other embodiments, the metal material may be nickel or a nickel alloy, which may be at least substantially coated with copper or a copper alloy.

A sheet blank includes a core substrate having a generally planar shape with opposed first and second sides. The core substrate is made of high-strength steel containing at least two of ferrite, martensite, bainite, and austenite and having an ultimate tensile strength of at least 490 MPa. A respective decarburized layer of the high-strength steel is formed on each of the first and second sides of the core substrate, wherein each respective decarburized layer contains a minimum ferrite content of at least 80 volume % ferrite and has a respective thickness of 5 to 100 microns. A respective transition layer of the high-strength steel may be formed between the core substrate and each respective decarburized layer, with each transition layer having a respective inner transition layer abutting the core substrate and a respective outer transition layer abutting the respective decarburized layer.

A series of welding filler wires with innovative composition design for fusion welding precipitation-hardened lightweight austenitic Fe—Mn—Al—C alloys. The first class of the welding filler wires is composed of 23-34 wt. % Mn, 7.5-11.5 wt. % Al, 1.35-1.95 wt. % C, with the balance being essentially Fe. After fusion welding, there are high-density of nano-sized (˜3-5 nm) (Fe,Mn).sub.3AlC carbides (κ-carbides) uniformly distributed within the austenite dendrite cells in the fusion zone (FZ). The amount of nano-sized (˜6-10 nm) κ-carbides existing within the eutectic regions is significantly increased and the size of the austenite dendrite cells is substantially reduced. The second class of welding filler wires has the composition of 23-34 wt. % Mn, 7.5-11.5 wt. % Al, 1.40-1.95 wt. % C, 0.1-2.5 wt. % Ti, 0.1-3.0 wt. % Nb, 0.1-2.5 wt. % V, with the balance being essentially Fe. The microstructure of the FZ in the as-welded condition results in formation of substantial amount of nano-sized (˜6-10 nm) face-centered-cubic structured ductile Ti-rich Ti-carbides, Nb-rich Nb-carbides and V-rich V-carbides within the eutectic regions. These carbides are extremely hard (2000˜3500 Hv), enhancing hardness of the obtained FZ.

An automobile undercarriage part of the present invention is an automobile undercarriage part including a welded joint in which a first steel sheet and a second steel sheet are overlapped and a fillet weld is formed between an end surface of the first steel sheet and a surface of the second steel sheet, in which a chemical composition of a weld metal that forms the welded joint contains, with respect to a total mass of the weld metal, by mass %, C: 0.02% to 0.20%, Si: more than 0% to less than 0.10%, Mn: 0.3% to 2.0%, Al: 0.002% to 0.30%, Ti: 0.005% to 0.30%, P: more than 0% to 0.015%, and S: more than 0% to 0.030%, and the following formula (1) and formula (2) are satisfied.

[Al]+[Ti]>0.05   Formula (1)

7×[Mn]−112×[Ti]−30×[Al]≤4.0   Formula (2)

A series of welding filler wires with innovative composition design for fusion welding precipitation-hardened lightweight austenitic Fe—Mn—Al—C alloys. The first class of the welding filler wires is composed of 23-34 wt. % Mn, 7.5-11.5 wt. % Al, 1.35-1.95 wt. % C, with the balance being essentially Fe. After fusion welding, there are high-density of nano-sized (˜3-5 nm) (Fe,Mn).sub.3AlC carbides (κ-carbides) uniformly distributed within the austenite dendrite cells in the fusion zone (FZ). The amount of nano-sized (˜6-10 nm) κ-carbides existing within the eutectic regions is significantly increased and the size of the austenite dendrite cells is substantially reduced. The second class of welding filler wires has the composition of 23-34 wt. % Mn, 7.5-11.5 wt. % Al, 1.40-1.95 wt. % C, 0.1-2.5 wt. % Ti, 0.1-3.0 wt. % Nb, 0.1-2.5 wt. % V, with the balance being essentially Fe. The microstructure of the FZ in the as-welded condition results in formation of substantial amount of nano-sized (˜6-10 nm) face-centered-cubic structured ductile Ti-rich Ti-carbides, Nb-rich Nb-carbides and V-rich V-carbides within the eutectic regions. These carbides are extremely hard (2000˜3500 Hv), enhancing hardness of the obtained FZ.

The disclosed technology generally relates welding electrodes, and more particularly to covered consumable welding electrodes. In an aspect, a consumable welding electrode comprises a core wire comprising a steel composition and a coating formed on the core wire. The coating comprises weld metal alloying elements comprising Fe, C, Mn, Si, Ni, Mo, V and Cr that are arranged such that an undiluted weld metal formed from the covered welding electrode has a combination of high tensile strength and high impact strength.