Abstract: A high toughness, ultra high-strength steel having an excellent stress corrosion cracking resistance with a yield stress of not less than 110 kgf/mm.sup.2, which comprises 0.06-0.20 wt % of C, not more than 0.35 wt % of Si, 0.05-1.0 wt % of Mn, 8-11 wt % of Ni, 0.2-2.5 wt % of Cr, 0.7-2.5 wt % of Mo, 0.05-0.2 wt % of V, 0.01-0.08 wt % of Al, not more than 0.005 wt % of N, not more than 0.003 wt % of O, provided that the value of Al (%).times.N (%).times.10.sup.4 is not more than 1.5, and the balance being substantially Fe and inevitable impurities.

Abstract: A high-strength steel for valve springs, consisting of 0.50-0.70 wt. % of carbon, 1.50-2.50 wt. % of silicon, 0.50-1.20 wt. % of manganese, 1.50-2.50 wt. % of nickel, 0.50-1.00 wt. % of chromium, 0.20.0.50 wt. % of molybdenum, 0.15-0.25 wt. % of vanadium, and the balance being iron and inevitably included inclusions. Also disclosed is a process for producing such a high-strength steel, which includes a step of minimizing oxygen in a melt of the steel, so as to reduce the oxygen content of the steel to 15 ppm or less, and a step of adding calcium to the melt and thereby controlling the form of the inclusions. The process may further include a step of minimizing titanium and nitrogen in the melt, so as to reduce the titanium and nitrogen content of the steel to 50 ppm or less, and 60 ppm or less, respectively.

Abstract: A low-alloy steel suitable for use in caster shells for continuous aluminum casting operations. It has a lower carbon and chromium content than prior art steels, and exhibits high yield strength at elevated temperatures, excellent toughness over the entire temperature range of aluminum casting, and decreased heat checking.

Abstract: A method for manufacturing a low-alloy steel product having a very high hardenability in relation to its alloying content is disclosed. The method includes the steps of melting the steel; adding thereto a micro-alloying ingredient selected from group consisting of aluminum, titanium, and aluminum and titanium together; superheating the melt to a temperature of at least 1625.degree. C., holding the melt at the temperature level for at least two minutes; teeming and casting the melt to form ingots and hot-working the ingots to form a low alloy steel product of the following composition:______________________________________ Element Wt % ______________________________________ C 0.3-0.55 Mn 0.3-1.5 Si trace-1.0 Cr .75-1.8 Ni trace-2.0 Mo 0.05-0.4 V 0.05-0.15 P 0.03 Max S trace-0.05 Al 0.04-0.1 or Ti 0.015-0.08 or Al + Ti 0.04-0.

Abstract: A continuously cast steel consisting of0.32 to 1.0% carbon0.20 to 3.0% manganese,up to 2.0% silicon,max. 0.05% phosphorus,max. 0.05% sulphur,0.002 to 0.008% nitrogen,0.015 to 0.08% zirconium,0.010 to 0.10% aluminium,up to 3.5% chromium,up to 3.5% nickel andup to 0.5% molybdenumrest iron and unavoidable impurities, wherein the zirconium: nitrogen ratio being 7:1 to 10:1 and the austenite grain size being ASTM 6 or a smaller grain size number.

Abstract: Isotropic tool steel consisting essentially of necessary elements as tool steel, less than 0.005 weight % of S and less than 30 ppm of O, the balance being substantially Fe. The necessary elements are, by weight, 0.10-0.70% of C, 2.00% or less of Si, 2.00% or less of Mn, 7.00% or less of Cr, 0.20-12.00% of W and/or Mo alone or in combination (1/2W+Mo), 3.00% or less of V. They may further include at least one of 4.00% or less of Ni, 6.50% or less of Co and 0.20% or less of N. The isotropic tool steel has cleanliness with respect to non-metallic inclusions defined by JIS G 0555 of dA60.times.400.ltoreq.0.010% and d(B+C)60.times.400.ltoreq.0.020%, and a ratio of transverse direction toughness to longitudinal direction toughness of more than 0.70. Since it is highly resistant to the generation and propagation of cracks and fracture, dies for hot working made therefrom can enjoy a long life.

Abstract: A superplastic hot working method for a duplex-phase, nitrogen-containing ferrous alloy and stainless steel, and a superplastic duplex-phase ferrous alloy are disclosed. The ferrous alloy comprises: at least one of Si and Mn in an amount of not less than 0.5% and not less than 1.7%, respectively; and N: at least 0.01% in solid solution, wherein Si eq and Mn eq which are defined as:Si eq=Si+(2/3)(Cr+Mo), and Mn eq=Mn+2 Ni+60 C+50 N,satisfy the formula:(5/6)(Si eq)-15/2.ltoreq.Mn eq.ltoreq.(11/5)(Si eq)-77/5,and its superplastic hot working is carried out by deforming the alloy heated to 700.degree.-1200.degree. C. at a strain rate of 1.times.10.sup.-6 S.sup.-1 to 1.times.10.sup.0 S.sup.-1. In another aspect, superplastic hot working of a duplex-phase stainless steel comprising Cr: 10.0-35.0%, Ni: 2.0-18.0%, Mo: 0-6.0%, and N: 0.005-0.3% and having the values of Si eq and Mn eq as above is carried out by deforming the steel at a strain rate of from 1.times.10.sup.-6 S.sup.-1 to 1.times.10.sup.1 S.sup.

Abstract: A method for manufacturing a low-alloy steel product having a very high hardenability in relation to its alloying content is disclosed. The method includes the steps of melting the steel; adding thereto a micro-alloying ingredient selected from the group consisting of aluminum, titanium, and aluminum and titanium together; superheating the melt to a temperature of at least 1625.degree. C., holding the melt at that temperature level for at least two minutes; teeming and costing the melt to form ingots and hot-working the ingots to form a low alloy steel product.

Abstract: A heat-resisting steel suitable for use in valve parts of internal combustion engine is disclosed, which consists essentially by weight percentage of 0.3-0.5% of C, more than 1.0% to 2.5% of Si, 0.1-2.0% of Mn, 0.5-7.0% of Cr, 0.3-2.0% of Mo and 0.1-1.0% of V as basic ingredients, at least one of 0.3-2.0% of Cu and 0.001-0.05% of REM as sub-ingredients and if necessary, at least one of 0.1 to less than 2.0% of Ni, 0.1-1.5% of W and 0.03-1.0% of Nb+Ta, and the balance of Fe and inevitable impurities.