A solid wire for electroslag welding, including Fe and, by mass % based on a total mass of the wire: C: more than 0% and 0.03% or less; Si: more than 0% and 0.10% or less; Mn: more than 0% and 0.25% or less; Ni: 10.5%-14.0%; S: more than 0% and 0.010% or less; Al: more than 0% and 0.250% or less; REM: 0.002%-0.080%; and O: more than 0% and 0.0090% or less.

A solid wire for electroslag welding, including Fe and, by mass % based on a total mass of the wire: C: more than 0% and 0.03% or less; Si: more than 0% and 0.10% or less; Mn: more than 0% and 0.25% or less; Ni: 10.5%-14.0%; S: more than 0% and 0.010% or less; Al: more than 0% and 0.250% or less; REM: 0.002%-0.080%; and O: more than 0% and 0.0090% or less.

An austenitic stainless steel having excellent processability and surface characteristics and a method of manufacturing the austenitic stainless steel are disclosed. The austenitic stainless steel includes, by weight %, 0.005% to 0.15% of carbon (C), 0.1% to 1.0% of silicon (Si), 0.1% to 2.0% of manganese (Mn), 6.0% to 10.5% of nickel (Ni), 16% to 20% of chromium (Cr), 0.005% to 0.2% of nitrogen (N), the remainder iron (Fe) and other unavoidable impurities, wherein a degree of Ni surface negative segregation defined by the following Formula (1) is in a range of 0.6 to 0.9.
(C.sub.Ni-Min)/(C.sub.Ni-Ave)  Formula (1), where C.sub.Ni-Min is a minimum concentration of Ni on the surface of the austenitic stainless steel and C.sub.Ni-Ave is an average concentration of Ni on the surface of the austenitic stainless steel.

An austenitic stainless steel having excellent processability and surface characteristics and a method of manufacturing the austenitic stainless steel are disclosed. The austenitic stainless steel includes, by weight %, 0.005% to 0.15% of carbon (C), 0.1% to 1.0% of silicon (Si), 0.1% to 2.0% of manganese (Mn), 6.0% to 10.5% of nickel (Ni), 16% to 20% of chromium (Cr), 0.005% to 0.2% of nitrogen (N), the remainder iron (Fe) and other unavoidable impurities, wherein a degree of Ni surface negative segregation defined by the following Formula (1) is in a range of 0.6 to 0.9.
(C.sub.Ni-Min)/(C.sub.Ni-Ave)  Formula (1), where C.sub.Ni-Min is a minimum concentration of Ni on the surface of the austenitic stainless steel and C.sub.Ni-Ave is an average concentration of Ni on the surface of the austenitic stainless steel.

Described herein are thin metal strips having hot rolled exterior side surfaces characterized as being primarily or substantially free of all prior austenite grain boundaries, or at least primarily or substantially free of all prior austenite grain boundaries, and including elongated surface structure. As a result, because the prior austenite grain boundaries are not primarily or substantially present, all such prior austenite grain boundaries are not susceptible to grain boundary etching due to acid etching or pickling. In particular examples, the thin metal strips undergo hot rolling performed with a coefficient of friction equal to or greater than 0.20 with or without use of lubrication.

A seamless steel pipe of the present invention is a seamless steel pipe having a composition that includes, in mass %, C: 0.02 to 0.12%, Si: 0.010 to 1.00%, Mn: 0.10 to 2.00%, P: 0.050% or less, S: 0.004% or less, Al: 0.010 to 0.100%, Cu: 0.03 to 0.80%, Ni: 0.02 to 0.50%, Cr: 0.55 to 1.00%, Sb: 0.005 to 0.20%, and the balance Fe and incidental impurities, and satisfying the following formula (1),

1.7×Cu*+11×Cr*+3.8×Sb*≥13.5   (1), where Cu*, Cr*, and Sb* represent average concentrations of Cu, Cr, and Sb, respectively, in mass %, as measured in a region 0.5 to 2.0 mm away from an outer surface of the steel pipe, the seamless steel pipe having a yield strength of 230 MPa or more, and a tensile strength of 380 MPa or more.

A seamless steel pipe of the present invention is a seamless steel pipe having a composition that includes, in mass %, C: 0.02 to 0.12%, Si: 0.010 to 1.00%, Mn: 0.10 to 2.00%, P: 0.050% or less, S: 0.004% or less, Al: 0.010 to 0.100%, Cu: 0.03 to 0.80%, Ni: 0.02 to 0.50%, Cr: 0.55 to 1.00%, Sb: 0.005 to 0.20%, and the balance Fe and incidental impurities, and satisfying the following formula (1),

1.7×Cu*+11×Cr*+3.8×Sb*≥13.5   (1), where Cu*, Cr*, and Sb* represent average concentrations of Cu, Cr, and Sb, respectively, in mass %, as measured in a region 0.5 to 2.0 mm away from an outer surface of the steel pipe, the seamless steel pipe having a yield strength of 230 MPa or more, and a tensile strength of 380 MPa or more.

An alloy material is provided that has a chemical composition consisting of, in mass %, C: 0.030% or less, Si: 0.01 to 1.0%, Mn: 0.01 to 2.0%, P: 0.030% or less, S: 0.0050% or less, Cr: 28.0 to 40.0%, Ni: 32.0 to 55.0%, sol. Al: 0.010 to 0.30%, N: more than 0.30% and not more than 0.000214×Ni.sup.2−0.03012×Ni+0.00215×Cr.sup.2−0.08567×Cr+1.927, O: 0.010% or less, Mo: 0 to 6.0%, W: 0 to 12.0%, Ca: 0 to 0.010%, Mg: 0 to 0.010%, V: 0 to 0.50%, Ti: 0 to 0.50%, Nb: 0 to 0.50%, Co: 0 to 2.0%, Cu: 0 to 2.0%, REM: 0 to 0.10%, and the balance: Fe and impurities, and in which Fn1=Mo+(½)W is 1.0 to 6.0, and a yield strength at a 0.2% proof stress is 1103 MPa or more.

An austenitic stainless steel material is provided that has high creep strength even when used at an average operation temperature of more than 600 to 750° C. after welding with higher heat input, and furthermore, has excellent stress relaxation cracking resistance even after use for a long time period at the average operation temperature after welding with higher heat input. The steel material has a chemical composition which consists of, in mass %, C: 0.030% or less, Si: 1.50% or less, Mn: 2.00% or less, P: 0.045% or less, S: 0.0300% or less, Cr: 15.00 to 25.00%, Ni: 8.00 to 20.00%, N: 0.050 to 0.250%, Nb: 0.10 to 1.00%, Mo: 0.05 to 5.00%, and B: 0.0005 to 0.0100%, with the balance being Fe and impurities, and a ratio of the dissolved N amount (mass %) with respect to the content of N (mass %) in the steel material is 0.40 to 0.90.

A welded structure including a base material made of duplex stainless steel and a welded portion formed by welding the base materials to each other, wherein the base material has a predetermined chemical composition, a volume fraction of a ferrite phase in a metallographic structure of a weld metal of the welded portion is 45 to 75%, a ratio of a hardness of the weld metal to a hardness of the base material is 0.80 to 1.20, and an amount of precipitates formed in the ferrite phase of the weld metal is less than 10% in area fraction.