A degradable, high-strength zinc composition suitable for use in producing degradable tools and components for in use in oil and gas and related application fields.

A degradable, high-strength zinc composition suitable for use in producing degradable tools and components for in use in oil and gas and related application fields.

A plated steel material comprising a steel base material and an Al—Zn—Mg-based plating layer formed on a surface of the steel base material, wherein the plating layer has a predetermined chemical composition, and in a surface structure of the plating layer, there is, by area ratio, 2.0% or more of an acicular Al—Zn—Si—Ca phase.

A plated steel material comprising a steel base material and an Al—Zn—Mg-based plating layer formed on a surface of the steel base material, wherein the plating layer has a predetermined chemical composition, and in a surface structure of the plating layer, there is, by area ratio, 2.0% or more of an acicular Al—Zn—Si—Ca phase.

A plated steel including a plated layer on a surface of a steel, in which Expression 1 of 0≤Cr+Ti+Ni+Co+V+Nb+Cu+Mn 0.25 and Expression 2 of 0≤Sr+Sb+Pb+B+Li+Zr+Mo+W+Ag+P≤0.50 are satisfied, and Expression 3 of I(MgZn.sub.2 (41.31°))/IΣ(MgZn.sub.2)≤0.265 and Expression 6 of 0.150≤{I(MgZn.sub.2 (20.79°))+I(MgZn.sub.2 (42.24°))}/IΣ(MgZn.sub.2) are further satisfied in an X-ray diffraction pattern of a surface of the plated layer measured using Cu-Kα rays under a condition that an X-ray output is 40 kV and 150 mA.

A plated steel including a plated layer on a surface of a steel, in which Expression 1 of 0≤Cr+Ti+Ni+Co+V+Nb+Cu+Mn 0.25 and Expression 2 of 0≤Sr+Sb+Pb+B+Li+Zr+Mo+W+Ag+P≤0.50 are satisfied, and Expression 3 of I(MgZn.sub.2 (41.31°))/IΣ(MgZn.sub.2)≤0.265 and Expression 6 of 0.150≤{I(MgZn.sub.2 (20.79°))+I(MgZn.sub.2 (42.24°))}/IΣ(MgZn.sub.2) are further satisfied in an X-ray diffraction pattern of a surface of the plated layer measured using Cu-Kα rays under a condition that an X-ray output is 40 kV and 150 mA.

A method for manufacturing a hot-rolled and coated steel sheet having a thickness between 1.8 mm and 5 mm. The method contains the steps of: providing a semi-product having a composition containing: 0.04%≤C≤0.38%, 0.40%≤Mn≤3%, 0.005%≤Si≤0.70%, 0.005%≤Al≤0.1%, 0.001%≤Cr≤2%, 0.001%≤Ni≤2%, 0.001%≤Ti≤0.2%, Nb≤0.1%, B≤0.010%, 0.0005%≤N≤0.010%, 0.0001%≤S≤0.05%, 0.0001%≤P≤0.1%, Mo≤0.65%, W≤0.30%, Ca≤0.006%, hot-rolling with a final rolling temperature FRT, to obtain a hot-rolled steel product having a thickness between 1.8 mm and 5 mm, then cooling down to a coiling temperature T.sub.coil satisfying: 450° C.≤T.sub.coil≤T.sub.coilmax with T.sub.coilmax=650−140×fγ, T.sub.coilmax being expressed in degrees Celsius and fγ designating the austenite fraction just before the coiling, and coiling to obtain a hot-rolled steel substrate, pickling and coating the hot-rolled steel substrate with Al or an Al alloy by continuous hot-dipping in a bath, to obtain a hot-rolled and coated steel sheet containing a hot-rolled steel sheet and an Al or an Al alloy coating, having a thickness between 10 and 33 μm, on each side of the hot-rolled steel sheet.

Provided are: an arc welding method that suppresses occurrences of blow holes in initial parts and final parts in a Zn plated steel sheet and reduces the occupancy ratio for blow holes in the welded part as a whole; and a welded joint.

A method which allows process-stable hot-dip coating of Ni-alloy steel flat products in a cost- and resource-effective manner, including the following steps: a) provision of a steel flat product obtained by cold- or hot-rolling; b) within 1-30 s, heating the steel flat product to a holding temperature between 700 and 1100° C., under a heating atmosphere of N2; c) holding the steel flat product at the holding temperature for a holding duration of 10-120 s under a holding atmosphere of N2; d) cooling the steel flat product from the holding temperature to a strip inlet temperature of 430-800° C.; and e) passing the steel flat product through an inlet zone, in which an inert or reducing inlet atmosphere predominates, and passing the steel flat product through a melt bath, wherein TP1>TP2>TP4.

A method which allows process-stable hot-dip coating of Ni-alloy steel flat products in a cost- and resource-effective manner, including the following steps: a) provision of a steel flat product obtained by cold- or hot-rolling; b) within 1-30 s, heating the steel flat product to a holding temperature between 700 and 1100° C., under a heating atmosphere of N2; c) holding the steel flat product at the holding temperature for a holding duration of 10-120 s under a holding atmosphere of N2; d) cooling the steel flat product from the holding temperature to a strip inlet temperature of 430-800° C.; and e) passing the steel flat product through an inlet zone, in which an inert or reducing inlet atmosphere predominates, and passing the steel flat product through a melt bath, wherein TP1>TP2>TP4.