A spot welded joint of at least two steel sheets is provided. At least one of the steel sheets presents yield strength above or equal to 600 MPa, an ultimate tensile strength above or equal to 1000 MPa, uniform elongation above or equal to 15%. The base metal chemical composition includes 0.05≤C≤0.21%, 4.0≤Mn≤7.0%, 0.5≤Al≤3.5%, Si≤2.0%, Ti≤0.2%, V≤0.2%, Nb≤0.2%, P≤0.025%, B≤0.0035%, and the spot welded joint contains a molten zone microstructure containing more than 0.5% of Al and containing a surface fraction of segregated areas lower than 1%, said segregated areas being zones larger than 20 μm.sup.2 and containing more than the steel nominal phosphorus content.

A butt joint deep penetration laser welding method is used for joining facing end sections of flat steel products, each having a carbon content CS<0.02%. In order to improve such a method such that an improved weld quality in terms of geometry and strength is achievable with it, at least one carbon-containing carrier material is inserted into a butt joint gap between the end sections, the carbon content of which is C.sub.T≥20.Math.C.sub.S, preferably C.sub.T≥100.Math.C.sub.S, and/or carbon is inserted into the butt joint gap or applied to at least one end section, such that the volume of the carbon inserted into the butt joint gap corresponds to 1% to 20% of the volume of a melt produced by a butt joint deep penetration laser welding process.

A pulsed laser printing module for a contact lens, comprises a steel mold, a pulsed laser device and a forming case. The steel mold is configured for transferring pigment. The pulsed laser device is configured for transmitting ultrashort laser pulses having pulse time widths less than 10.sup.−9 seconds. The ultrashort laser pulses etch the surface of the steel mold to remove a coating of the steel mold to form an etched layer. The forming case has a lower member and an upper member. The lower member is a concavity, and an inner surface of the lower member is provided with a lower curved surface. The upper member is provided with a protrusion corresponding to the lower member, and an outer surface of the protrusion is provided with an upper curved surface corresponding to the lower curved surface. The protrusion is capable of being placed in a concavity of the lower member to form a gap between the lower curved surface and the upper curved surface.

Method for the manufacture of a galvannealed steel sheet includes the following steps: A) the provision of a pre-coated steel sheet coated with a first coating comprising iron and nickel, such steel sheet having the following chemical composition in weight percent 0.10<C<0.40%, 1.5<Mn<3.0%, 0.7<Si<2.0%, 0.05<Al<1.0%, 0.75<(Si+Al)<3.0% and on a purely optional basis, one or more elements such as Nb≤0.5%, B≤0.005%, Cr≤1.0%, Mo≤0.50%, Ni≤1.0%, Ti≤0.5%, the remainder of the composition making up of iron and inevitable impurities resulting from the elaboration, B) the thermal treatment of such pre-coated steel sheet at a temperature between 600 to 1000° C., C) the hot-dip coating of the steel sheet obtained in step B) with a second coating based on zinc and D) an alloying treatment to form a galvannealed steel sheet.

In a vehicle to which the present joining structure of vehicle steel plates is applied, a third welded portion is set between a first welded portion and a second welded portion, wherein at the first welded portion, a pillar outer rear flange, an SM outer rear flange, a pillar inner rear flange are joined to one another; and at the second welded portion, the pillar outer rear flange and the pillar inner rear flange are joined to each other. At the third welded portion, the pillar outer rear flange and the SM outer rear flange are joined to each other. Accordingly, a tensile load F acting on the pillar outer rear flange is distributed toward the SM outer rear flange side.

A pre-coated steel sheet wherein at least a region at the periphery (7) of at least one (6a,6b) of the opposite faces (6a,6b) of said pre-coated sheet (1,1′) is coated with an additional coating (8) selected for increasing the vapor pressure between the pre-coating (2) and said additional coating (8) during a laser welding method up to a critical pressure at which the pre-coating (2) is ejected away from the weld (14). Preferably, the vaporization temperature of the additional coating (8) is greater than the vaporization temperature of the pre-coating (2) and the additional coating includes gammagene elements like carbon and/or nickel. A steel part obtained by laser welding, preferably butt laser welding, of at least a first and second pre-coated steel sheet (1,1′) as above indicated is also provided.

A method is provided for determining whether post-weld heat treatments should be required for external attachment welds in applications where stress corrosion cracking is a possibility. According to the method, residual stress values are measured in test samples welded at high input heat levels and test samples welded at low input heat levels for a variety of different wall thickness. A threshold residual stress level is determined according to a method of selecting a common pipe used in industry and measuring the residual stress level in the longitudinal seam of the pipe. The measured residual stress values for the high and low heat input welds are compared against the threshold to determine whether for a particular wall thickness, the high and low input data exceeds the threshold, indicating whether post-weld heat treatments are required.

The present invention relates to a pre-stressed steel sheet and a method a method of manufacturing the same.

An embodiment of the present invention provides a pre-stressed steel sheet comprising: a base material; and a plurality of weld lines formed on the base materials, wherein the average spacing between each pair of the weld lines is equal to or greater than five times the width of the weld lines and equal to or less than half the width of the steel sheet.

According to an aspect of the present invention, a pre-stressed steel sheet having improved bendability can be provided, and accordingly when the pre-stressed steel sheet is applied to a structural member such as a girder or beam, the bendability of a structure can be improved.

A cleaning method involves, in a first step, emitting a first laser light toward the surface of a steel material targeted for cleaning to clean the surface of the steel material. Next, in a second step, a second laser light is emitted toward the surface of the steel material to remove an oxide layer formed on the surface of the steel material due to irradiation with the first laser light. In this step, the oxide layer formed on the surface of the steel material is removed, by emitting the second laser light at a power in a range that does not cause a new oxide layer to form on the surface of the steel material.

A weld-line generating apparatus includes a point-cloud-data acquiring unit that acquires 3D point cloud data of workpieces to be welded that are arranged in a predetermined space, an edge extracting unit that extracts 3D point cloud data of edges from the 3D point cloud data acquired by the point-cloud-data acquiring unit, a workpiece point-cloud-data generating unit that generates a 3D point cloud data component of each of the workpiece based on 3D point cloud data that is obtained by removing the 3D point cloud data of edges extracted by the edge extracting unit from the 3D point cloud data acquired by the point-cloud-data acquiring unit, and a weld-line generating unit 24 that generates weld lines for the workpieces based on the 3D point cloud data components of the workpieces generated by the workpiece point-cloud-data generating unit.