Abstract: A high-precision method for evaluating creep damage of high tension heat resistant steel used in high temperature exposed apparatuses involves comparing particle size behavior varying with creep damage progress of crystal grains having a crystal orientation difference of about 2 degrees or more, preferably 3 degrees or more at an evaluated part on the basis of a working curve or a working map prepared in advance by looking for the relation of grain sizes to creep damage extent. A high-precision apparatus evaluates the creep damage of high tension heat resistant steel used in high temperature exposed apparatuses.

Abstract: A welding method and a welded joint for high strength, temperature resistant steels produce the same strength as the base metal in the welded joint, thereby resolving strength problems in the heat affected area by making a simple change to the welding method. Additionally, this advantage is extended to high strength ferrite heat resistant steels by providing a multi-pass buildup welding method for such high strength ferrite heat resistant steels. A multi-layered cap 15a fusion area extends past the heat affected area 13 that lies outside groove 11, and the surface area of the foregoing extension that is required to impart the same level of creep strength as is inherent in the base metal is based on the relationship between the groove width and the base metal thickness shown as hatched area in FIG. 1(B).

Abstract: The present invention provides a high-precision method for evaluating creep damage of high tension heat resistant steel used in high temperature exposing apparatuses comprising comparing particle size behavior varying with creep damage progress of crystal grains having a crystal orientation difference of about 2 degrees or more, preferably 3 degrees or more at an evaluated part on the basis of a working curve or a working map prepared in advance by looking for the relation of grain sizes to creep damage extents, and also provides a high-precision apparatus for evaluating creep damage of high tension heat resistant steel used in high temperature exposing apparatuses comprising a measuring means for measuring particle size variation behavior of crystal grains or sub grains having a crystal orientation difference of about 2 degrees or more with regard to a specimen at the evaluated part of high tension heat resistant steel and a working curve or a working map prepared in advance by looking for the relation of th

Abstract: This invention provides a welding method and a welded joint for high strength, temperature resistant steels that produces the same strength as the base metal in the welded joint, thereby resolving the strength problems in the heat affected area by making a simple change to the welding method, and additionally, to extend this advantage to high strength ferrite heat resistant steels by providing a multi-pass buildup welding method for such high strength ferrite heat resistant steels. The multi-layered cap 15a fusion area extends past the heat affected area 13 that lies outside groove 11, and the surface area of the foregoing extension that is required to impart the same level of creep strength as is inherent in the base metal is based on the relationship between the groove width and the base metal thickness shown as hatched area in FIG. 1(B).

Abstract: A high strength, low alloy, heat resistant steel having excellent weldability has an average crystal grain diameter of at most 110 &mgr;m and consists essentially of, by mass %: C: 0.03-0.15%, Si: at most 1%, Mn: at most 2%, P: at most 0.03%, S: at most 0.03%, Ni: at most 0.5%, Cu: at most 0.5%, Cr: 1.8-2.8%, V: 0.1-0.3%, Nb: 0.01-0.08%, Mo: 0.05-0.35%, W: 1.2-1.8%, Ti: 0.001-0.05%, B: 0-0.02%, Al: at most 0.1%, O: at most 0.1%, N: in an amount satisfying the formula [%N]≦[%Ti]+5[%B]+0.004, and a remainder of unavoidable impurities.

Abstract: Disclosed is a heat-resisting steel comprising 0.05 to 0.15% by weight of carbon, 0.01 to 0.1% by weight of silicon, 0.01 to 1% by weight of manganese, 8 to 11% by weight of chromium, 0.1 to 0.8% by weight of nickel, 0.1 to 0.3% by weight of vanadium, a total of 0.01 to 0.2% by weight of niobium and tantalum, 0.001 to 0.01% by weight of nitrogen, 0.01 to 0.5% by weight of molybdenum, 0.9 to 3.5% by weight of tungsten, 0.1 to 4.5% by weight of cobalt, 0.001 to 0.01% by weight of boron, and the balance being iron and incidental impurities, as well as other similar heat-resisting steels. Thus, this invention provides heat-resisting steels which are 12Cr steel-based materials having excellent high-temperature strength and can be used at steam temperatures of 593.degree. C. or above, and forged steel products such as steam turbine rotors for high-temperature use.

Abstract: This invention provides a welding material for low chromium (Cr) ferritic heat-resisting steel having high toughness, wherein the chemical composition of welding metal comprises, in weight %, carbon (c) 0.04-0.1%, silicon (Si) 0.1-0.6%, manganese (Mn) 0.1-0.6%, phosphorus (P) 0.0005-0.03%, sulfur (S) 0.0005-0.015%, chromium (Cr) 1.75-2.5%, nickel (Ni) 0.01-0.8%, molybdenum (Mo) 0.05-1.5%, vanadium (V)0.01-0.5%, tungsten (W) 0.05-2%, niobium (Nb) 0.01-0.2%, tantalum (Ta) 0.01-0.5%, aluminum (Al) 0.003-0.05%, boron (B) 0.0001-0.01%, nitrogen (N) 0.003-0.03%, and the remainder comprises iron and inevitable impurities. The welding material satisfies the following formula: C+Cr/20+Mo/15+V/10+W/7+5B.ltoreq.0.8%. According to this invention, the welding material is suitable for welding low Cr ferritic heat-resisting steels having high strength such as those used in steam generators and heat exchangers of boilers, etc.

Abstract: This invention provides low-Cr ferritic steels and low-Cr ferritic cast steels having excellent high-temperature strength and weldability. These low-Cr ferritic steels and low-Cr ferritic cast steels consist essentially of, on a weight percentage basis, 0.03 to 0.12% C, 0.05 to 0.7% Si, 0.05 to 1% Mn, 0.002 to 0.025% P, 0.001 to 0.015% S, 0.3 to 3% Cr, 0.01 to 1% Ni, 0.05 to 3% Mo, 0.01 to 0.5% V, 0.1 to 3% W, 0.01 to 0.2% Nb, 0.02 to 1.5% Re, 0.003 to 0.05% Al, 0.0001 to 0.01% B, 0.003 to 0.03% N, and the balance being Fe and incidental impurities, and have excellent high-temperature strength and weldability.

Abstract: A low Mn-low Cr ferritic heat resistant steel consisting essentially of, in weight %: 0.02-0.20% C, up to 0.7% Si, less than 0.1% Mn, up to 0.8% Ni, 0.8-3.5% Cr, 0.01-3.0% W, 0.1-0.5% V, 0.01-0.20% Nb, 0.001-0.05% Al, 0.0005-0.05% Mg, 0.0005-0.01% B, less than 0.05% N, up to 0.03% P, up to 0.015% S, 0.001-0.05% Ti and the balance Fe and incidental impurities, wherein the B content is defined so as to satisfy the following formula (14/11)B>N-N(V/51)/{(C/12)+(N/14)}-N(Nb/93)/{(C/12)+(N/14)}-N(Ti/48)/{C/12 )+(N/14)}. The steel can further contain optionally 0.01-1.5% Mo, and/or one or more elements selected from the group consisting of 0.01-0.2% La, 0.01-0.2% Ce, 0.01-0.2% Y, 0.01-0.2% Ca, 0.01-0.2% Ta and 0.01-0.2% Zr. The steel can be used in place of the austenitic steels or high Cr ferritic steels, since it has remarkably improved toughness, workability and weldability, and excellent creep properties at elevated temperatures.

Abstract: A method of forming a weld joint between an austenitic stainless steel and a ferritic steel. The ferritic steel contains 0.03 to 0.12% carbon, 0.70% or less silicon, 0.10 to 1.50% manganese, 0.030% or less phosphorus, 0.015% or less sulphur, 1.50 to 3.50% chromium, 0.40% or less molybdenum, 1.00 to 3.00% tungsten, 0.10 to 0.35% vanadium, 0.01 to 0.10% niobium, 0.030% or less Sol. aluminum, 0.020% or less boron, and 0.030% or less nitrogen.

Abstract: A low-Cr ferritic steel with improved toughness as well as creep strength is disclosed, which consists essentially of, by weight %:C: 0.03-0.12%, Si: 0.70% or less, Mn: 0.10-1.50%,Ni: 2.0% or less, Cr: 1.50-3.50%, W: 1.0-3.0%,V: 0.10-0.35%, Nb: 0.01-0.10%,B: 0.00010-0.020%, N: 0.005% or less,Al: 0.005% or less,Ti: not less than 0.001% but less than 0.05%,Cu: 0.10-2.50%,at least one of La, Ce, Y, Ca, Zr, Ta each in an amount of 0-0.20%, and Mg in an amount of 0-0.05%,Mo in an amount of 0-0.40%, anda balance of Fe and incidental impurities including P: not more than 0.030% and S: not more than 0.015%.

Abstract: A high-nitrogen ferritic heat-resisting steel with high vanadium content comprises, in weight percent, 0.01-0.30% C, 0.02-0.80% Si, 0.20-1.00% Mn, 8.00-13.00% Cr, 0.005-1.00% Mo, 0.20-1.50% W, 0.30-2.00% V, and 0.10-0.50% N and being controlled to include less than 0.020% Nb, the balance being Fe and unavoidable impurities. A method of producing the steel comprises melting and equilibrating the steel components in an atmosphere of a mixed gas of a prescribed nitrogen partial pressure or nitrogen gas and thereafter casting or solidifying the resulting melt in an atmosphere controlled to have a total pressure of not less than 2.77 bar and a nitrogen partial pressure of not less than 1.0 bar, with the relationship between the nitrogen partial pressure p and the total pressure P beingP>2.77pthereby obtaining sound ingot free of blowholes.

Abstract: A high-nitrogen ferritic heat-resisting steel with high niobium content comprises, in weight per cent, 0.01-0.30% C, 0.02-0.80% Si, 0.20-1.00% Mn, 8.00-13.00% Cr, 0.005-1.00% Mo, 0.20-1.50% W, 0.05-1.00% V, over 0.12 up to 2.00% Nb and 0.10-0.50%N, the balance being Fe and unavoidable impurities. A method of producing the steel comprises melting and equilibrating the steel components in an atmosphere of a mixed gas of a prescribed nitrogen partial pressure or nitrogen gas and thereafter casting or solidifying the resulting melt in an atmosphere controlled to have a total pressure of not less than 2.5 bar and a nitrogen partial pressure of not less than 1.0 bar, with the relationship between the nitrogen partial pressure p and the total pressure P beingP>2.5p.

Abstract: A low-alloy steel consists essentially, on a weight basis, of: C: 0.03-0.12%, Si: at most 0.7%, Mn: 0.1-1.5%, Ni: at most 0.8%, P: at most 0.03%, S: at most 0.015%, Cr: 1.5-3.5%, W: 1-3%, V: 0.1-0.35%, Nb: 0.01-0.1%, B: 0.0001-0.02%, N: less than 0.005%, Al: less than 0.005%, Ti: 0.001-0.1%, optionally one or more elements selected from the group consisting of: La, Ce, Y, Ca, Zr, and Ta: 0.01-0.2%, Mg: 0.0005-0.05%, and Mo: 0.01-0.4%, and a balance of Fe and incidental impurities, wherein the Ti and Ni contents satisfy the following inequality:0.080.gtoreq.Ti(%)-(48/14).times.N(%).gtoreq.0.003.The steel has improved creep strength at high temperatures and improved toughness. It can be substituted for expensive austenitic stainless steels or high-Cr ferritic steels.

Abstract: A high-nitrogen ferritic heat-resisting steel comprises, in weight percent, 0.01-0.30% C, 0.02-0.80% Si, 0.20-1.00% Mn, 8.00-13.00% Cr, 0.50-3.00% W, 0.005-1.00% Mo, 0.05-0.50% V, 0.02-0.12% Nb and 0.10-0.50% N and is controlled to include not more than 0.050% P, not more than 0.010% S and not more than 0.020% O, the balance being Fe and unavoidable impurities. The steel may optionally comprise (A) one or both of 0.01-1.00% Ta and 0.01-1.00% Hf and/or (B) one or both of 0.0005-0.10% Zr and 0.01-0.10% Ti. A method of producing the steel comprises melting and equilibrating the steel components in an atmosphere of a mixed gas of a prescribed nitrogen partial pressure or nitrogen gas and thereafter casting or solidifying the melt in an atmosphere controlled to have a nitrogen partial pressure of not less than 1.0 ata and a total pressure of not less than 4.0 ata, with the relationship between the partial pressure p and the total pressure P.sub.t being10.sup.P <P.sub.t.sup.0.37 +log.sub.10 6.

Abstract: A high-nitrogen ferritic heat-resisting steel comprises, in weight per cent, 0.01-0.30% C, 0.02-0.80% Si, 0.20-1.00% Mn, 8.00-13.00% Cr, 0.50-3.00% W, 0.005-1.00% Mo, 0.05-0.50% V, 0.02-0.12% Nb and 0.10-0.50% N and is controlled to include not more than 0.050% P, not more than 0.010% S and not more than 0.020% O, the balance being Fe and unavoidable impurities. The steel may optionally comprise (A) one or both of 0.01-1.00% Ta and 0.01-1.00% Hf and/or (B) or both of 0.0005-0.10% Zr and 0.01-0.10% Ti. A method of producing the steel comprises melting and equilibrating the steel components in an atmosphere of a mixed gas of a prescribed nitrogen partial pressure or nitrogen gas and thereafter casting or solidifying the melt in an atmosphere controlled to have a nitrogen partial pressure of not less than 1.0 ata and a total pressure of not less than 4.0 ata, with the relationship between the partial pressure p and the total pressure P.sub.t being10.sup.P <P.sub.t.sup.0.37 +log.sub.10 6.

Abstract: High strength heat-resistant low alloy steels have a chemical composition of, on weight basis, a carbon content of 0.03-0.12%, a silicon content not higher than 1%, a manganese content of 0.2-1%, a phosphor content not higher than 0.03%, a sulfur content not higher than 0.03%, a nickel content not higher than 0.8%, a chromium content of 0.7-3%, a molybdenum content of 0.3-0.7%, a tungsten content of 0.6-2.4%, a vanadium content of 0.05-0.35%, a niobium content of 0.01-0.12% and a nitrogen content being 0.01-0.05% with the balance of iron and inevitable impurities, wherein the molybdenum content and the tungsten content satisfy the relationship 0.8%.ltoreq.(Mo+1/2W)%.ltoreq.1.5%; or a carbon content of 0.03-0.12%, a silicon content not higher than 1%, a manganese content of 0.2-1%, a phosphor content not higher than 0.03%, a sulfur content not higher than 0.03%, a nickel content not higher than 0.8%, a chromium content of 0.7-3%, a molybdenum content of 0.3-1.5%, a vanadium content of 0.05-0.

Abstract: An automatic structure analyzing/processing apparatus for surface structure of material includes a structure observing device for observing structure of a surface of material to produce an electrical image signal thereof, a sample stage disposed opposite to the observing means an image processing device for converting the image signal from the structure observing device to digital signal and expanding or contracting a desired image reproduced from a memory means or combining a plurality of images reproduced from the memory means to produce an image signal, the memory device storing the digital signal processed by the image processing device, and a display device for displaying the image signal produced from the image processing device as an image, whereby the structure of the surface of material is stored in the memory as the image and examination of the structure can be made readily in a short time.

Abstract: A high-strength high-Cr ferritic, heat-resistant steel exhibiting improved high-temperature, long-term creep strength and a process for producing the same are disclosed. The steel consists essentially of, by weight %:______________________________________ C: not more than 0.2%, Si: not more than 1.0%, Mn: 0.1-1.5%, P: not more than 0.03%, S: not more than 0.03%, Ni: not more than 1.0%, Cr: 5.0-15%, Mo: 0.02-3.0%, W: not more than 4.0%, sol. Al: 0.05-0.04%, N: not more than 0.07%, ______________________________________at least one of V: 0.01-0.4% and Nb: 0.01-0.3%, B: 0-0.02%,at least one of Ca, Ti, Zr, Y, La, and Ce: 0-0.2%, andthe balance Fe and incidental impurities,A.sub.cl point defined by Formula (1) below being 820 or higher.

Abstract: A method of evaluating residual life of a heat-resistant steel member after and during service at high temperature and stress makes use of a residual life evaluation diagram which is obtained beforehand on a plurality of samples of the heat-resistant steel and which represents the relationship between the life consumption and a parameter which indicates the life consumed. The parameter may be data concerning the density of an alloy element such as molybdenum and chromium, or the state of degradation in the metallurgical structure and/or state of precipitation of carbides.