Abstract: A high-Ni alloy having excellent weld-hot-cracking resistance includes, in mass %, Cr: 16-30%, Ni: 18-50%, Al: 0.01-1.0%, and Ti: 0.01-1.5%. In a first aspect of the invention, a relationship between number density of TiC precipitates having 1.0 ?m or more of equivalent circle diameter and Mg content in steel satisfies formula (1) below. In a second aspect of the invention, S average concentration in oxide- and sulfide-inclusions is 0.70 mass % or more. In a third aspect of the invention, mass ratios of CaO, MgO, and Al2O3 in inclusions, where O or S is detected, satisfy formula (2), the mass ratios being respectively calculated from average concentrations of Ca, Mg and Al in the inclusions, (1) number density of TiC (number of pieces/mm2)?463?9.5×Mg concentration in steel (mass ppm) and (2) [CaO?0.6×MgO] (mass %)/[CaO+MgO+Al2O3] (mass %)?0.20.

Abstract: A high-Ni alloy having excellent weld-hot-cracking resistance includes, in mass %, Cr: 16-30%, Ni: 18-50%, Al: 0.01-1.0%, and Ti: 0.01-1.5%. In a first aspect of the invention, a relationship between number density of TiC precipitates having 1.0 ?m or more of equivalent circle diameter and Mg content in steel satisfies formula (1) below. In a second aspect of the invention, S average concentration in oxide- and sulfide-inclusions is 0.70 mass % or more. In a third aspect of the invention, mass ratios of CaO, MgO, and Al2O3 in inclusions, where O or S is detected, satisfy formula (2), the mass ratios being respectively calculated from average concentrations of Ca, Mg and Al in the inclusions, (1) number density of TiC (number of pieces/mm2)?463?9.5×Mg concentration in steel (mass ppm) and (2) [CaO?0.6×MgO] (mass %)/[CaO+MgO+Al2O3] (mass %)?0.20.

Abstract: An alloy material is provided which contains elements including, in mass %, C: 0.010 to 0.10%, Si: more than 0.10% to 0.50% or less, Mn:0.05 to 0.50%, Ni:34.5 to 37.0%, and Nb:0.001 to 1.0%, and which satisfies [T0?T1-2], [C—Nb/7.7-Ta/15?0.045], [Nb-7.7C?0.30], and [Ta-15C?0.30]. Where, each symbol of an element in the above formulas represents a content (mass %) of the corresponding element, T0 represents a Curie temperature (° C.) of the alloy material, and T1 represents a Curie temperature (° C.) of the alloy material after the alloy material is held at 900° C. for one minute and thereafter is cooled under conditions such that an average cooling rate in a temperature range from 600 to 300° C. is 0.2° C./s.

Abstract: A duplex stainless steel and method of manufacturing the same, said steel having an amount of Cr in an extraction residue [Cr] of 0.005 to 0.050% and an amount of Nb in an extraction residue [Nb] of 0.001 to 0.080%, the [Nb]/[Cr] ratio being 0.2 or more. By slow cooling down to 800° C., then fast cooling down to 600° C., it is possible to control the precipitation of chromium nitrides and niobium nitrides, and by making the ratio [Nb]/[Cr] 0.2 or more, it is possible to raise the corrosion resistance. Further, by reducing Mn to less than 2.0% and N to 0.25% or less, then adding a trace amount of Nb, the effect of raising the critical pitting temperature CPT is obtained.

Abstract: The present invention has as its object to expand applications to types of steel having corrosion resistances of SUS 329J1 or more and has as its challenge to obtain duplex stainless steel which has excellent corrosion resistance in an environment with a high chloride ion concentration close to brackish water or seawater and having a high economicalness. The inventors discovered that by reducing Mn to less than 2.0% and N to 0.25% or less, then adding a trace amount of Nb, the effect of raising the critical pitting temperature CPT is easily obtained. Further, they heated steel to which a trace amount of Nb was added for solution heat treatment, then examined the effects on the precipitation of Cr nitrides and Nb nitrides and developed duplex stainless steel raised in pitting resistance of the matrix material. That is, by slow cooling down to 800° C.

Abstract: This alloying element-saving hot rolled duplex stainless steel material contains, by mass %, C: 0.03% or less, Si: 0.05% to 1.0%, Mn: 0.5% to 7.0%, P: 0.05% or less, S: 0.010% or less, Ni: 0.1% to 5.0%, Cr: 18.0% to 25.0%, N: 0.05% to 0.30% and Al: 0.001% to 0.05%, with a remainder being Fe and inevitable impurities, wherein the alloying element-saving hot rolled duplex stainless steel material is produced by hot rolling, a chromium nitride precipitation temperature TN is in a range of 960° C. or lower, a yield strength is 50 MPa or more higher than that of a hot rolled steel material which is subjected to a solution heat treatment, and the alloying element-saving hot rolled duplex stainless steel material is as hot rolled state, and is not subjected to a solution heat treatment. This clad steel plate includes a duplex stainless steel as a cladding material, the duplex stainless steel has the above composition, and the chromium nitride precipitation temperature TN is in a range of 800° C. to 970° C.

Abstract: One aspect of this duplex stainless steel contains, in mass %, C: 0.03% or less, Si: 0.05% to 1.0%, Mn: 0.1% to 7.0%, P: 0.05% or less, S: 0.0001% to 0.0010%, Ni: 0.5% to 5.0%, Cr: 18.0% to 25.0%, N: 0.10% to 0.30%, Al: 0.05% or less, Ca: 0.0010% to 0.0040%, and Sn: 0.01% to 0.2%, with the remainder being Fe and inevitable impurities, wherein a ratio Ca/O of the amounts of Ca and O is in a range of 0.3 to 1.0, and a pitting index PI shown by formula (1) is in a range of less than 30, PI=Cr+3.3Mo+16N??(1).

Abstract: A nitrogen-rich two-phase stainless steel that has corrosion resistance equal to that of standard type of two-phase stainless steel and is not susceptible to corrosion in a welding heat-affected part, wherein the austenite phase area ratio is 40-70%, the PI value expressed by formula (1) is 30-38, the NI value expressed by formula (2) is 100-140, and the ?pre expressed by formula (3) is 1350-1450. (1) PI=Cr+3.3Mo+16N (2) NI=(Cr+Mo)/N.

Abstract: The present invention provides a lean duplex stainless steel able to suppress the drop in corrosion resistance and toughness of a weld heat affected zone comprising, by mass %, C: 0.06% or less, Si: 0.1 to 1.5%, Mn: 2.0 to 4.0%, P: 0.05% or less, S: 0.005% or less, Cr: 19.0 to 23.0%, Ni: 1.0 to 4.0%, Mo: 1.0% or less, Cu: 0.1 to 3.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, O: 0.007% or less, N: 0.10 to 0.25%, and Ti: 0.05% or less, having a balance of Fe and unavoidable impurities. An Md30 value is 80 or less, an Ni-bal is ?7.1 to 4, an austenite phase area percentage is 40 to 70%, and a 2×Ni+Cu is 3.5 or more: Md30=551?462×(C+N)?9.2×Si?8.1×Mn?29×(Ni+Cu)?13.7×Cr?18.5×Mo?68×Nb; Ni-bal=(Ni+0.5Mn+0.5Cu+30C+30N)?1.1(Cr+1.5Si+Mo+W)+8.2 and N(%)?0.37+0.03×(Ni-bal).

Abstract: One aspect of this duplex stainless steel contains, in mass %, C: 0.03% or less, Si: 0.05% to 1.0%, Mn: 0.1% to 7.0%, P: 0.05% or less, S: 0.0001% to 0.0010%, Ni: 0.5% to 5.0%, Cr: 18.0% to 25.0%, N: 0.10% to 0.30%, Al: 0.05% or less, Ca: 0.0010% to 0.0040%, and Sn: 0.01% to 0.2%, with the remainder being Fe and inevitable impurities, wherein a ratio Ca/O of the amounts of Ca and O is in a range of 0.3 to 1.0, and a pitting index PI shown by formula (1) is in a range of less than 30, PI=Cr+3.3Mo+16N??(1).

Abstract: The present invention provides duplex stainless steel superior in corrosion resistance in a chloride environment and impact properties suitable as a material for pumps for seawater desalination plants, facilities and equipment, and materials for chemical tanks, that is, duplex stainless steel characterized by containing, by mass %, C: 0.06% or less, Si: 0.05 to 3.0%, Mn: 0.1 to 6.0%, P: 0.05% or less, S: 0.010% or less, Ni: 1.0 to 10.0%, Cr: 18 to 30%, Mo: 5.0% or less, Cu: 3.0% or less, N: 0.10 to 0.40%, Al: 0.001 to 0.08% or less, Ti: 0.003 to 0.05%, Mg: 0.0001 to 0.0030%, and O: 0.010% or less, having a product of an activity coefficient fN of N, Ti content, and N content fN×Ti×N of 0.00004%2 or more, and having a product of Ti content and N content Ti×N of 0.008%2 or less.

Abstract: A welding wire for austenitic stainless steel welding contains, in percent by mass, C: 0.005 through 0.05%, Si: 0.1 through 1.0%, Mn: 1.0 through 3.5%, Cr: 25.0 through 28.0%, Ni: 16.0 through 23.9%, Mo: 1.6 through 3.0%, Cu: 0.1 through 0.5%, Al: 0.001 through 0.02%, and N: more than 0.30 through 0.50%, limiting O to 0.03% or less, P to 0.03% or less, and S to 0.005% or less, and having a ratio of a Cr equivalent to Ni equivalent (Cr equivalent/Ni equivalent) within a range between 0.85 and 1.2 and a PI value of 35 or more, the remainder being iron and unavoidable impurities.

Abstract: A nitrogen-rich two-phase stainless steel that has corrosion resistance equal to that of standard type of two-phase stainless steel and is not susceptible to corrosion in a welding heat-affected part, wherein the austenite phase area ratio is 40-70%, the PI value expressed by formula (1) is 30-38, the NI value expressed by formula (2) is 100-140, and the ?pre expressed by formula (3) is 1350-1450. (1) PI=Cr+3.

Abstract: This alloying element-saving hot rolled duplex stainless steel material contains, by mass %, C: 0.03% or less, Si: 0.05% to 1.0%, Mn: 0.5% to 7.0%, P: 0.05% or less, S: 0.010% or less, Ni: 0.1% to 5.0%, Cr: 18.0% to 25.0%, N: 0.05% to 0.30% and Al: 0.001% to 0.05%, with a remainder being Fe and inevitable impurities, wherein the alloying element-saving hot rolled duplex stainless steel material is produced by hot rolling, a chromium nitride precipitation temperature TN is in a range of 960° C. or lower, a yield strength is 50 MPa or more higher than that of a hot rolled steel material which is subjected to a solution heat treatment, and the alloying element-saving hot rolled duplex stainless steel material is as hot rolled state, and is not subjected to a solution heat treatment. This clad steel plate includes a duplex stainless steel as a cladding material, the duplex stainless steel has the above composition, and the chromium nitride precipitation temperature TN is in a range of 800° C. to 970° C.

Abstract: An austenitic stainless steel hot-rolled steel material can be provided which has sea-water resistance and strength superior to conventional steel. Low-temperature toughness can be maintained, which is preferable in a structural member of speedy craft. The steel material can include an austenitic stainless steel hot-rolled steel material which excels in the properties of corrosion resistance, proof stress, and low-temperature toughness. In such austenitic stainless steel hot-rolling steel material, e.g., PI [=Cr+3.3(Mo+0.5W)+16N] ranges from 35 to 40, ? cal [=2.9 (Cr+0.3Si+Mo+0.5W)?2.6 (Ni+0.3Mn+0.25Cu+35C+20N)?18] ranges from ?6 to +2, and a 0.2% proof stress at room temperature is not less than 550 MPa, Charpy impact value measured using a V-notch test piece at ?40° C. is not less than 100 J/cm2, and the pitting potential measured in a deaerated aqueous solution of 10% NaCl at 50° C. (Vc?100) is not less than 500 mV (as it relates to saturated Ag/AgCl).

Abstract: This martensitic stainless steel contains, in terms of percent by mass: C: 0.003% to 0.03%; Si: 0.01% to 1.0%; Mn: 3.0% to 6.0%; P: 0.05% or less; S: 0.003% or less; Ni: 1.0% to 3.0%; Cr: 15.0% to 18.0%; Mo: 0% to 1.0%; Cu: 0% to 2.0%; Ti: 0% to 0.05%; N: 0.05% or less; Al: 0.001% to 0.1%; and O: 0.005% or less, with a remainder being Fe and inevitable impurities, wherein a total amount of C and N is in a range of 0.060% or less, ?max represented by the formula 1 is in a range of 80 or more, and ?pot represented by the formula 2 is in a range of 60 to 90. ?max=420×C %+470×N %+23×Ni %+9×Cu %+7×Mn %?11.5×Cr %?11.5×Si %?52×Al %+189??Formula 1 ?pot=700×C %+800×N %+10×(Mn %+Cu %)+20×Ni %?9.3×Si %?6.2×Cr %?9.3×Mo %?74.4×Ti %?37.2×Al %+63.2??Formula 2 Here, C %, N %, Ni %, Cu %, Mn %, Cr %, Si %, A1%, Mo %, and Ti % represent the contents (mass %) of the respective elements.

Abstract: An austenitic stainless steel hot-rolled steel material can be provided which has seawater resistance and strength superior to conventional steel. Low-temperature toughness can be maintained, which is preferable in a structural member of speedy craft. The steel material can include an austenitic stainless steel hot-rolled steel material which excels in the properties of corrosion resistance, proof stress, and low-temperature toughness. In such austenitic stainless steel hot-rolling steel material, e.g., PI [=Cr+3.3(Mo+0.5W)+16N] ranges from 35 to 40, ? cal [=2.9 (Cr+0.3Si +Mo+0.5W)?2.6 (Ni+0.3Mn+0.25Cu+35C+20N)?18] ranges from ?6 to +2, and a 0.2% proof stress at room temperature is not less than 550 MPa, Charpy impact value measured using a V-notch test piece at ?40° C. is not less than 100 J/cm2, and the pitting potential measured in a deaerated aqueous solution of 10% NaCl at 50° C. (Vc'100) is not less than 500 mV (as it relates to saturated Ag/AgCl).

Abstract: An austenitic stainless steel hot-rolled steel material can be provided which has sea-water resistance and strength superior to conventional steel. Low-temperature toughness can be maintained, which is preferable in a structural member of speedy craft. The steel material can include an austenitic stainless steel hot-rolled steel material which excels in the properties of corrosion resistance, proof stress, and low-temperature toughness. In such austenitic stainless steel hot-rolling steel material, e.g., PI [=Cr+3.3(Mo+0.5W)+16N] ranges from 35 to 40, ? cal [=2.9(Cr+0.3Si+Mo+0.5W)?2.6(Ni+0.3Mn+0.25Cu+35C+20N)?18] ranges from ?6 to +2, and a 0.2% proof stress at room temperature is not less than 550 MPa, Charpy impact value measured using a V-notch test piece at ?40° C. is not less than 100 J/cm2, and the pitting potential measured in a deaerated aqueous solution of 10% NaCl at 50° C. (Vc?100) is not less than 500 mV (as it relates to saturated Ag/AgCl).

Abstract: The present invention provides a lean duplex stainless steel able to suppress the drop in corrosion resistance and toughness of a weld heat affected zone and is characterized by containing, by mass %, C: 0.06% or less, Si: 0.1 to 1.5%, Mn: 2.0 to 4.0%, P: 0.05% or less, S: 0.005% or less, Cr: 19.0 to 23.0%, Ni: 1.0 to 4.0%, Mo: 1.0% or less, Cu: 0.1 to 3.0%, V: 0.05 to 0.5%, Al: 0.003 to 0.050%, 0: 0.007% or less, N: 0.10 to 0.25%, and Ti: 0.05% or less, having a balance of Fe and unavoidable impurities, having an Md30 value expressed by formula (1) of 80 or less, having an Ni-bal expressed by formula (2) of ?8 to ?4, having a relationship between the Ni-bal and the N content satisfying formula (3), having an austenite phase area percentage of 40 to 70%, and having a 2×Ni+Cu of 3.5 or more: Md30=551?462×(C+N)?9.2×Si?8.1×Mn?29×(Ni+Cu)?13.7×Cr?18.5×Mo?68×Nb ??(1) Ni-bal=(Ni+0.5Mn+0.5Cu+30C+30N)?1.1(Cr+1.5Si+Mo+W)+8.2 ??(2) N(%)?0.37+0.

Abstract: An austenitic stainless steel hot-rolled steel material can be provided which has sea-water resistance and strength superior to conventional steel. Low-temperature toughness can be maintained, which is preferable in a structural member of speedy craft. The steel material can include an austenitic stainless steel hot-rolled steel material which excels in the properties of corrosion resistance, proof stress, and low-temperature toughness. In such austenitic stainless steel hot-rolling steel material, e.g., PI [=Cr+3.3(Mo+0.5W)+16N] ranges from 35 to 40, ? cal [=2.9(Cr+0.3Si+Mo+0.5W)?2.6(Ni+0.3Mn+0.25Cu+35C+20N)?18] ranges from ?6 to +2, and a 0.2% proof stress at room temperature is not less than 550 MPa, Charpy impact value measured using a V-notch test piece at ?40° C. is not less than 100 J/cm2, and the pitting potential measured in a deaerated aqueous solution of 10% NaCl at 50° C. (Vc'100) is not less than 500 mV (as it relates to saturated Ag/AgCl).