A rail comprises a predetermined chemical composition. In a hardness distribution in a region from a rail head surface to a depth of 16.0 mm, a part having higher hardness than V1 that is minimum hardness in a first internal region is present in a second internal region, and hardness of the rail head surface is HBW 400 to 520 and average hardness in the region from the rail head surface to the depth of 16.0 mm is HBW 350 or more.

A drill string component, in particular a drilling collar component, an MWD component, or an LWD component for use in oilfield technology and particularly in deep drilling, is provided. A method of making a drill string component, and a steel alloy useful in making a drill string component, are also provided.

A drill string component, in particular a drilling collar component, an MWD component, or an LWD component for use in oilfield technology and particularly in deep drilling, is provided. A method of making a drill string component, and a steel alloy useful in making a drill string component, are also provided.

An NPR steel material for rock bolt and a production method thereof are disclosed. The NPR steel material for rock bolt has a composition, in weight percent, consisting of: C: 0.4-0.7%, Mn: 15-20%, Si: ≤0.1%, Cu: ≤0.03%, Cr: ≤0.01%, Ni: ≤0.02%, S: ≤0.001%, P: ≤0.001%, and the rest being Fe and unavoidable impurity elements. The NPR steel material for rock bolt and the production method thereof effectively solve the problem that rock bolts in the prior art have low tensile strength and low effective elongation. The NPR steel material for rock bolt has a yield strength adjustable in the range of 500-1100 MPa, and an elongation adjustable in the range of 10-80%.

The present invention relates to a wire rod of which softening heat treatment can be omitted, and a manufacturing method therefor. One embodiment of the present invention provides a wire rod of which softening heat treatment can be omitted, and a manufacturing method therefor, the wire rod comprising, by wt %, 0.2-0.45% of C, 0.02-0.4% of Si, 0.3-1.5% of Mn, 0.3-1.5% of Cr, 0.02-0.05% of Al, 0.01-0.5% of Mo, 0.01% or less of N, and the balance of Fe and other inevitable impurities, and having a microstructure consisting of, by area %, 40% or more of proeutectoid ferrite based on an equilibrium phase, 40% or more of regenerated pearlite and bainite, and 20% or less of martensite, and wherein the colony average size of the pearlite in the region amounting to ⅖ to ⅗ of the diameter is 5 μm or less.

A wire rod and steel wire having superior magnetic characteristics and a method for manufacturing same, wherein the wire rod and the steel wire can be used in transformers, vehicles, electric or electronic products, or the like which require low iron loss and high permeability. Provided are a wire rod and steel wire having superior magnetic characteristics and a method for manufacturing same, wherein the wire rod or the steel wire comprises, by wt %, 0.03 to 0.05% of C, 3.0 to 5.0% of Si, 0.1 to 2.0% of Mn, 0.02 to 0.08% of Al, 0.0015 to 0.0030% of N, and the remainder being Fe and unavoidable impurities. The wire rod and steel wire having directional properties may be provided by a general manufacturing process without using expensive alloying elements and without having to add a manufacturing facility.

A wire rod and steel wire having superior magnetic characteristics and a method for manufacturing same, wherein the wire rod and the steel wire can be used in transformers, vehicles, electric or electronic products, or the like which require low iron loss and high permeability. Provided are a wire rod and steel wire having superior magnetic characteristics and a method for manufacturing same, wherein the wire rod or the steel wire comprises, by wt %, 0.03 to 0.05% of C, 3.0 to 5.0% of Si, 0.1 to 2.0% of Mn, 0.02 to 0.08% of Al, 0.0015 to 0.0030% of N, and the remainder being Fe and unavoidable impurities. The wire rod and steel wire having directional properties may be provided by a general manufacturing process without using expensive alloying elements and without having to add a manufacturing facility.

To provide a steel for bolts with excellent delayed fracture resistance and cold forgeability while maintaining the strength as a steel material, and also to provide a bolt producing from such a steel for bolts.

The steel for bolts according to the present invention includes, in percent by mass: 0.20 to 0.40% of C; 1.5 to 2.5% of Si; 0.20 to 1.5% of Mn; more than 0% and 0.03% or less of P; more than 0% and 0.03% or less of S; 0.05 to 1.5% of Cr; 0.01 to 0.10% of Al; 0.0003 to 0.01% of B; 0.002 to 0.020% of N; and one or two elements selected from the group consisting of 0.02 to 0.10% of Ti and 0.02 to 0.10% of Nb, with the balance being iron and inevitable impurities.

To provide a steel for bolts with excellent delayed fracture resistance and cold forgeability while maintaining the strength as a steel material, and also to provide a bolt producing from such a steel for bolts.

The steel for bolts according to the present invention includes, in percent by mass: 0.20 to 0.40% of C; 1.5 to 2.5% of Si; 0.20 to 1.5% of Mn; more than 0% and 0.03% or less of P; more than 0% and 0.03% or less of S; 0.05 to 1.5% of Cr; 0.01 to 0.10% of Al; 0.0003 to 0.01% of B; 0.002 to 0.020% of N; and one or two elements selected from the group consisting of 0.02 to 0.10% of Ti and 0.02 to 0.10% of Nb, with the balance being iron and inevitable impurities.

The present invention relates to a method for manufacturing a round-rod shaped alloy ingot by hot forging, containing suspending a primary alloy ingot having a round-rod shape in a columnar mold while one end of the primary alloy ingot is held, pouring a molten metal formed of a heat-retaining metal into the columnar mold so as to apply a coating of the heat-retaining metal to the entire circumference of the primary alloy ingot, to obtain a forging alloy ingot, taking the forging alloy ingot out from the columnar mold, then subjecting the forging alloy ingot to a hot forging while an end portion of the forging alloy ingot is gripped as a gripping portion, and removing the coating of the heat-retaining metal.