Abstract: A method of producing a ferritic heat-resistant steel welded joint, the method including: a multi-layer welding step in which a ferritic heat-resistant steel base material including B at 0.006% by mass to 0.023% by mass is multi-layer welded using a Ni-based welding material for heat-resistant alloy, wherein root pass welding is performed under a welding condition such that a ratio of an area [SBM] that has been melted of the ferritic heat-resistant steel base material to an area [SWM] of a weld metal, in a transverse cross-section of a weldment after the root pass welding but before second pass welding in the multi-layer welding step, satisfies the following formula (1): 0.1?[SBM]/[SWM]??50×[% BBM]+1.3, with respect to a mass percent of B, [% BBM], which is included in the ferritic heat-resistant steel base material.

Abstract: 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.

Abstract: A method of producing a ferritic heat-resistant steel welded joint, the method including: a multi-layer welding step in which a ferritic heat-resistant steel base material including B at 0.006% by mass to 0.023% by mass is multi-layer welded using a Ni-based welding material for heat-resistant alloy, wherein root pass welding is performed under a welding condition such that a ratio of an area [SBM] that has been melted of the ferritic heat-resistant steel base material to an area [SWM] of a weld metal, in a transverse cross-section of a weldment after the root pass welding but before second pass welding in the multi-layer welding step, satisfies the following formula (1): 0.1?[SBM]/[SWM]??50×[% BBM]+1.3, with respect to a mass percent of B, [% BBM], which is included in the ferritic heat-resistant steel base material.

Abstract: There is provided an austenitic heat resistant alloy including a chemical composition that contains, in mass percent: C: 0.04 to 0.18%, Si: 1.5% or less; Mn: 2.0% or less, P: 0.020% or less, S: 0.030% or less, Cu: 0.10% or less, Ni: 20.0 to 30.0%, Cr: 21.0 to 24.0%, Mo: 1.0 to 2.0%, Nb: 0.10 to 0.40%, Ti: 0.20% or less, Al: 0.05% or less, N: 0.10 to 0.35%, and B: 0.0015 to 0.005%, with the balance: Fe and impurities, the austenitic heat resistant alloy satisfying [P+6B?0.040].

Abstract: An austenitic heat-resistant steel weld metal with low high-temperature cracking susceptibility and good creep strength is provided. The austenitic heat-resistant steel weld metal has a chemical composition of, in mass %: 0.06% -0.14% C; 0.1%-0.6%Si; 0.1%-1.8%Mn; up to 0.025% P; up to 0.003% S; 25%-35% Ni; 20%-24% Cr; more than 4.5% and up to 7.5% W; 0.05%-0.5% Nb; 0.05%-0.4% V; 0.1%-0.35% N; up to 0.08% Al; up to 0.08% O; and 0.0005 to 0.005% B, fn1 expressed by the following Equation (1) being not less than 10: fn1=10(Nb+V)+1.5W+20N+1500B?25Si ??(1), where, for Nb, V, W, N, B and Si in Equation (1), the contents of the named elements in mass % are substituted.

Abstract: A welding material for austenitic heat resistant steel is provided that has a chemical composition which consists of, by mass %, C: 0.06 to 0.14%, Si: 0.10 to 0.40%, Mn: 2.0 to 4.0%, P: 0.020% or less, Cu: 2.0 to 4.0%, Ni: 15.0 to 19.0%, Cr: 16.0 to 20.0%, Mo: 0.50 to 1.50%, Nb: 0.30 to 0.60%, N: 0.10 to 0.30%, Al: 0.030% or less, O: 0.020% or less, S: 0 to 0.0030%, Sn: 0 to 0.0030%, Bi: 0 to 0.0030%, Zn: 0 to 0.0030%, Sb: 0 to 0.0030%, As: 0 to 0.0030%, V: 0 to 0.50%, Ti: 0 to 0.50%, Ta: 0 to 0.50%, Co: 0 to 2.0%, B: 0 to 0.020%, Ca: 0 to 0.020%, Mg: 0 to 0.020%, REM: 0 to 0.06%, with the balance being Fe and impurities, and which contains two or more types of element selected from S, Sn, Bi, Zn, Sb and As within a range that satisfies [0.0005?S+Sn+Bi+Zn+Sb+As?0.0030].

Abstract: A Ni-based heat resistant alloy of the present invention contains predetermined amounts of C, Si, Mn, P, S, N, O, Ni, Co, Cr, Mo, W, B, Al, Ti, Nb, REM, Mg, Ca, and the balance of Fe and impurities, wherein [0.1?Mo+W?12.0], [1.0?4×Al+2×Ti+Nb?12.0], and [P+0.2×Cr×B<0.035] are satisfied, a shortest distance from a center portion to an outer surface portion of a cross section of an alloy member is 40 mm or more, the cross section being perpendicular to a longitudinal direction of the alloy member, an austenite grain size number at the outer surface portion is ?2.0 to 4.0, a total content of Al, Ti and Nb which are present as precipitates obtained by extraction residue analysis satisfies [(Al+Ti+Nb)PB/(Al+Ti+Nb)PS?10.0], and [YSS/YSB?1.5] and [TSS/TSB?1.2] are satisfied at a normal temperature.

Abstract: The NiCrFe alloy according to the present invention has a chemical composition consisting of, in mass %, C: 0.03 to 0.15%, Si: not more than 1.00%, Mn: not more than 2.00%, P: not more than 0.040%, S: not more than 0.0050%, Cr: 18.0 to 25.0%, Ni: 25.0 to 40.0%, Ti: 0.10 to 1.60%, Al: 0.05 to 1.00%, N: not more than 0.020%, O: not more than 0.008%, and rare earth metal (REM): 0.001 to 0.100%, with the balance being Fe and impurities, the chemical composition satisfying Formulae (1) to (3): 0.50?Ti+48Al/27?2.20 ??(1) 0.40?Ti/(Ti+48Al/27)?0.80 ??(2) ?[REM/(A(REM))]?S/32?2/3.O/16?0 ??(3) where, each symbol of element in the formulae is substituted by the content (mass %) of the corresponding element, and A(REM) in Formula (3) is substituted by the atomic weight of each rare earth metal.

Abstract: A welded joint is obtained by using a welding material having a composition: Cr: 15.0 to 30.0%; and Ni: 40.0 to 70.0%, including: a base material having a composition: C: 0.03 to 0.075%; Si: 0.6 to 2.0%; Mn: 0.05 to 2.5%; P: up to 0.04%; S: up to 0.015%; Cr: more than 16.0% and less than 23.0%; Ni: not less than 20.0% and less than 30.0%; Cu: 0.5 to 10.0%; Mo: less than 1%; Al: up to 0.15%; N: 0.005 to 0.20%; O: up to 0.02%; Ca: 0 to 0.1%; REM: 0 to 0.15%; V: not less than 0% and less than 0.5%; and Nb: 0 to 2%, a balance being Fe and impurities and a first-layer weld metal including Fe content from 10 to 40%, all % by mass.

Abstract: An objective of the present invention is to provide an austenitic stainless steel that is excellent in polythionic acid SCC resistance and also excellent in creep ductility. An austenitic stainless steel according to the present invention includes a chemical composition consisting of, in mass %, C: 0.030% or less, Si: 0.10 to 1.00%, Mn: 0.20 to 2.00%, P: 0.040% or less, S: 0.010% or less, Cr: 16.0 to 25.0%, Ni: 10.0 to 30.0%, Mo: 0.1 to 5.0%, Nb: 0.20 to 1.00%, N: 0.050 to 0.300%, sol.Al: 0.0005 to 0.100%, and B: 0.0010 to 0.0080%, with the balance being Fe and impurities, and satisfying Formula (1): B+0.004?0.9C+0.017Mo2?0??(1) where symbols of elements in Formula (1) are to be substituted by contents of corresponding elements (mass %).

Abstract: An austenitic stainless steel includes base metal and a coating film formed on at least part of a surface of the base metal, a chemical composition of the base metal containing, in mass percent: C: 0.05% or less; Si: 1.0% or less; Mn: 2.0% or less; P: 0.040% or less; S: 0.010% or less; O: 0.020% or less; N: less than 0.050%; Ni: 12.0 to 27.0%; Cr: 15.0% or more to less than 20.0%; Cu: more than 3.5% to 8.0% or less; Mo: more than 2.0% to 5.0% or less; Co: 0.05% or less; Sn: 0.05% or less, V: 0 to 0.5%, Nb: 0 to 1.0%, Ti: 0 to 0.5%, W: 0 to 5.0%, Zr: 0 to 1.0%, Al: 0 to 0.5%, Ca: 0 to 0.01%, B: 0 to 0.01%, REM: 0 to 0.01%, and the balance: Fe and impurities, wherein a chemical composition at a maximum-Cr depth where a concentration of Cr in the coating film reaches a maximum satisfies, in at %, [(Cr+Ni+Cu+Mo)/Fe?1.0].

Abstract: There is provided a welding structure member excellent in corrosion resistance in an environment where high-concentration sulfuric acid condenses, the welding structure member including base material having a chemical composition containing, in mass percent, C?0.05%, Si?1.0%, Mn?2.0%, P?0.04%, S?0.01%, Ni: 12.0 to 27.0%, Cr: 15.0% or more to less than 20.0%, Cu: more than 3 0% to 8.0% or less, Mo: more than 2.0% to 5.0% or less, Nb?1.0%, Ti?0.5%, Co?0.5%, Sn?0.1%, W?5.0%, Zr?1.0%, Al?0.5%, N<0.05%, Ca?0.01%, B?0.01%, and REM?0.01%, with the balance: Fe and unavoidable impurities, and the welding structure member including including weld metal having a chemical composition containing, in mass percent, C?0.10%, Si?0.50%, Mn?3.5%, P?0.03%, S?0.03%, Cu?0.50%, Ni: 51.0 to 69.0%, Cr: 14.5 to 23.0%, Mo: 6.0 to 17.0%, Al?0.40%, Ti+Nb+Ta?4.90%, Co?2.5%, V?0.35%, and W?4.5%, with the balance: Fe and unavoidable impurities.

Abstract: There is provided a welding structure member excellent in corrosion resistance in an environment where high-concentration sulfuric acid condenses, the welding structure member including base material having a chemical composition containing, in mass percent, C?0.05%, Si?1.0%, Mn?2.0%, P?0.04%, S?0.01%, Ni: 12.0 to 27.0%, Cr: 15.0% or more to less than 20.0%, Cu: more than 3.0% to 8.0% or less, Mo: more than 2.0% to 5.0% or less, Nb?1.0%, Ti?0.5%, Co?0.5%, Sn?0.1%, W?5.0%, Zr?1.0%, Al?0.5%, N<0.05%, Ca?0.01%, B?0.01%, and REM?0.01%, with the balance: Fe and unavoidable impurities, and the welding structure member including weld metal having a chemical composition containing, in mass percent, C?0.10%, Si?0.50%, Mn?3.5%, P?0.03%, S?0.03%, Cu?0.50%, Ni: 51.0 to 80.0%, Cr: 14.5 to 23.0%, Mo?0.10%, Al?0.40%, Ti+Nb+Ta?4.90%, Co?2.5%, V?0.35%, and W?4.5%, with the balance: Fe and unavoidable impurities.

Abstract: A welded joint is obtained by using a welding material having a composition: Cr: 15.0 to 30.0%; and Ni: 40.0 to 70.0%, including: a base material having a composition: C: 0.03 to 0.075%; Si: 0.6 to 2.0%; Mn: 0.05 to 2.5%; P: up to 0.04%; S: up to 0.015%; Cr: more than 16.0% and less than 23.0%; Ni: not less than 20.0% and less than 30.0%; Cu: 0.5 to 10.0%; Mo: less than 1%; Al: up to 0.15%; N: 0.005 to 0.20%; O: up to 0.02%; Ca: 0 to 0.1%; REM: 0 to 0.15%; V: not less than 0% and less than 0.5%; and Nb: 0 to 2%, a balance being Fe and impurities and a first-layer weld metal including Fe content from 10 to 40%, all % by mass.

Abstract: A duplex stainless steel containing, by mass %: C: not more than 0.03%, Si: not more than 0.3%, Mn: not more than 3.0%, P: not more than 0.040%, S: not more than 0.008%, Cu: 0.2 to 2.0%, Ni: 5.0 to 6.5%, Cr: 23.0 to 27.0%, Mo: 2.5 to 3.5%, W: 1.5 to 4.0%, and N: 0.24 to 0.40%, the balance being Fe and impurities, wherein a ? phase susceptibility index X (=2.2Si+0.5Cu+2.0Ni+Cr+4.2Mo+0.2W) is not more than 52.0; a strength index Y (=Cr+1.5Mo+10N+3.5W) is not less than 40.5; and a pitting resistance equivalent PREW (=Cr+3.3(Mo+0.5W)+16N) is not less than 40. This duplex stainless steel is excellent in corrosion resistance and embrittlement cracking resistance.

Abstract: A duplex stainless steel containing, by mass %: C: not more than 0.03%, Si: not more than 0.3%, Mn: not more than 3.0%, P: not more than 0.040%, S: not more than 0.008%, Cu: 0.2 to 2.0%, Ni: 5.0 to 6.5%, Cr: 23.0 to 27.0%, Mo: 2.5 to 3.5%, W: 1.5 to 4.0%, and N: 0.24 to 0.40%, the balance being Fe and impurities, wherein a ? phase susceptibility index X (=2.2Si+0.5Cu+2.0Ni+Cr+4.2Mo+0.2W) is not more than 52.0; a strength index Y (=Cr+1.5Mo+10N+3.5W) is not less than 40.5; and a pitting resistance equivalent PREW (=Cr+3.3(Mo+0.5W)+16N) is not less than 40. This duplex stainless steel is excellent in corrosion resistance and embrittlement cracking resistance.