Abstract: Disclosed is a process for producing Fe—Ni alloys used for electron gun parts. The alloy consists of: all by weight, 30 to 55% of Ni; 0.05 to 2.00% of Mn; 0.001% to 0.050 of S; and the balance of Fe and inevitable impurities. The process substantially consists of melting, casting, hot working, cold rolling and annealing. The Fe—Ni alloy satisfies 0.0005≦((%Mn)*(%S))≦0.0100. The hot working is carried out at a temperature T defined by the following equation. 1050 ≦ T ⁢   ⁢ ° ⁢   ⁢ C . ≦ 9500 3.

Abstract: A soft cold-rolled steel sheet contains: 0.06 wt. % or less C, 0.1 wt. % or less Si, 0.5 wt. % or less Mn, 0.03 wt. % or less P, 0.03 wt. % or less S, 0.006 wt. % or less N, 0.009 wt. % or less B and the balance being Fe. The method comprises the steps of: continuously casting a steel to produce a slab; hot-rolling the slab to form a hot-rolled steel sheet; cold-rolling the hot-rolled steel sheet to produce a cold-rolled steel sheet; and continuously annealing the cold-rolled steel sheet.

Abstract: A method of and apparatus for manufacturing hot-rolled steel strips from a continuously cast primary material, preferably thin slabs, in a plurality of successive steps in a continuous operation is disclosed. In the invention, thin slabs, which leave an equalizing furnace, are heated above the maximum temperature that can be achieved in the equalizing furnace and are thereafter are broken down in a break-down train, with the broken-down thin slabs being subsequently recrystallized and cooled down to a rolling temperature before being finish-rolled in the finishing train.

Abstract: Cold rolled steel sheet with excellent deep drawability and excellent anti-aging properties, and manufacturing method. The cold rolled steel sheet comprises about C: above 0.015 to 0.150 wt %, Si: 1.0 wt % or less, Mn: 0.01 to 1.50 wt %, P: 0.10 wt % or less, S: 0.003 to 0.050 wt %, Al: 0.001 to below 0.010 wt %, N: 0.0001 to 0.0050 wt %, Ti: 0.001 wt % or more and Ti(wt %)/[1.5.times.S(wt %)+3.4.times.N(wt %)].ltoreq.about 1.0 and B: about 0.0001 to 0.0050 wt %, during annealing, grain growth is improved; Ti is added to form a nitride and a sulfide to avoid precipitation of fine TiC; B is added to precipitate Boron precipitates (Fe.sub.2 B, Fex(C,B)y) in a cooling the hot rolled steel sheet and in cooling step during annealing after cold rolling; a spherical cementite is precipitated and grown in which the Boron series precipitate is a precipitation site.

Abstract: A method of manufacturing a seamless steel pipe having excellent properties with high productivity in on-line processing, and an apparatus in which includes casting and heat treatment unit on-line. In the method the following steps (1) to (6) are successively performed. (1) A round billet is produced by continuous casting machine 1. (2) The billet is cooled to a temperature not higher than a Ar.sub.1 point, then heated and soaked in a furnace 3. (3) The billet is pierced by a piercer 5 at a strain rate of not higher than 200/sec and made into a hollow shell. (4) The hollow shell is elongated and finish rolled to make into a seamless steel pipe at an average strain rate of not lower than 0.01/sec and with a reduction ratio of not lower than 40%, and finishing the rolling at a temperature from 800.degree. C. to 1050.degree. C. (5) The seamless steel pipe is cooled to a temperature not higher than the Ar.sub.3 point at a cooling rate of not lower than 80.degree. C./min.

Abstract: A high speed tool steel and a manufacturing method therefor are disclosed, in which carbides are formed in the matrix in a uniform manner, thereby obtaining a high toughness and a high abrasion resistance. The high speed tool steel according to the present invention includes a basic composition of W.sub.a Mo.sub.b Cr.sub.c Co.sub.d V.sub.x C.sub.y Fe.sub.z where the subscripts meet in weight %: 5.0%.ltoreq.a.ltoreq.7.0%, 4.0%.ltoreq.b.ltoreq.6.0%, 3.0%.ltoreq.c.ltoreq.5.0%, 6.5%.ltoreq.d.ltoreq.9.5%, 2.2%.ltoreq.x.ltoreq.8.3%, 1.1%.ltoreq.y.ltoreq.2.18%, and 66.52%.ltoreq.z.ltoreq.73.7%. The final structure has carbides uniformly distributed within a martensite matrix, which are mainly MC and M.sub.6 C carbides. The method includes the steps of melting the above-defined alloy composition, gas spraying the melted alloy to form a bulk material, heat treating the bulk material to decompose the M.sub.2 C carbides to stabilize M.sub.6 C carbides and hot working the heat treated bulk material to a desired shape.

Abstract: A ferritic non-ridging stainless steel and process therefor. A chromium alloyed steel melt is deoxidized with a sub-equilibrium amount of titanium and nitrogen and continuously cast into a strip or a slab or cast into an ingot having an as-cast fine equiaxed microstructure substantially free of columnar grains. The as-cast steel contains .ltoreq.0.010% Al, up to 0.08% C, 0.10-1.50% Mn, .ltoreq.0.05% N, .ltoreq.1.5% Si, 8-25% Cr, <2.0% Ni and is deoxidized with titanium, all percentages by weight, the balance Fe and residual elements. Preferably, the titanium is controlled so that (Ti/48)/?(C/12)+(N/14)!>1.5. A hot processed continuous sheet may be formed from a continuously cast slab without surface grinding, may be descaled, cold reduced to a final thickness and recrystallization annealed. An anneal prior to cold reduction is not required to obtain an annealed sheet essentially free of ridging.

Abstract: The subject of the invention is a hot-rolled steel sheet with high strength and high drawability, whose composition, expressed in percentages by weight, is:C.ltoreq.0.12%;0.5.ltoreq.Mn.ltoreq.1.5%;0.ltoreq.Si.ltoreq.0.3%;0.ltoreq.P.ltoreq.0.1%;0.ltoreq.S.ltoreq.0.05%;0.01.ltoreq.Al.ltoreq.0.1%;0.ltoreq.Cr.ltoreq.1%;0.01.ltoreq.Nb.ltoreq.0.1%;0.ltoreq.Ti.sub.eff .ltoreq.0.05%, Ti.sub.eff being the content of titanium not in the form of nitrides, sulfides or oxides; and whose structure comprises at least 75% of ferrite hardened by precipitation of niobium or niobium and titanium carbides or carbonitrides, the remainder of the structure comprising at least 10% of martensite and possibly bainite and residual austenite. The subject of the invention is also processes for manufacturing such sheets.

Abstract: A rotor for steam turbine rotor made of a heat resistant steel having a composition, which contains 0.05 to 0.3% by weight of C, 8.0 to 13.0% by weight of Cr, 1.0% by weight or less (excluding 0%) of Si, 1.0% by weight or less (excluding 0%) of Mn, 2.0% by weight or less (excluding 0%) of Ni, 0.10 to 0.50% by weight of V, 0.50 to 5.0% by weight of W, 0.025 to 0.10% by weight of N, 1.5% by weight or less excluding 0%) of Mo, at least one element selected from the group consisting of 0.03 to 0.25% by weight of Nb and 0.03 to 0.50% by weight of Ta, 0 to 3% of Re, 0 to 5.0% by weight of Co, 0 to 0.05% by weight of B and the balance of Fe and inevitable impurities, and having a ferrite/martensite structure.

Abstract: This invention provides a ferritic heat-resistant steel having excellent HAZ softening resistance characteristics and exhibiting a high creep strength up to a high temperature of not lower than 500.degree. C., and a method of producing such a steel, the steel comprising in terms of mass %, 0.01 to 0.30% of C, 0.02 to 0.80% of Si, 0.20 to 1.50% of Mn, 0.50 to 5.00% of Cr, 0.01 to 1.50% of Mo, 0.01 to 3.50% of W, 0.02 to 1.00% of V, 0.01 to 0.50% of Nb, 0.001 to 0.06% of N, one or both of 0.001 to 0.8% of Ti and 0.001 to 0.8% of Zr, wherein a value (Ti+Zr) in (Cr, Fe, Ti, Zr) of a M.sub.23 C.sub.6 type carbide in the steel is 5 to 65%, and the present invention provides a method of producing the same.

Abstract: The subject of the invention is a hot-rolled steel sheet with high strength and high drawability, whose composition, expressed in percentages by weight, is:C.ltoreq.0.12%;0.5.ltoreq.Mn.ltoreq.1.5%;0.ltoreq.Si.ltoreq.0.3%;0.ltoreq.P.ltoreq.0.1%;0.ltoreq.S.ltoreq.0.05%;0.01.ltoreq.Al.ltoreq.0.1%;0.ltoreq.Cr.ltoreq.1%;0.03.ltoreq.Ti.sub.eff .ltoreq.0.15%, Ti.sub.eff being the content of titanium not in the form of nitrides, sulfides or oxides;0.ltoreq.Nb.ltoreq.0.05%; and whose structure comprises at least 75% of ferrite hardened by precipitation of Ti or Ti and Nb carbides or carbonitrides, the remainder of the structure comprising at least 10% of martensite and possibly bainite and residual austenite. The subject of the invention is also processes for manufacturing such sheets.

Abstract: High-strength high-ductility steel whose chemical composition, by weight, comprises from 0.15% to 0.35% of carbon, from 0% to 3% of silicon, from 0% to 3% of aluminium, from 0.1% to 4.5% of manganese, from 0% to 9% of nickel, from 0% to 6% of chromium, from 0% to 3% of the sum of tungsten divided by two plus molybdenum, from 0% to 0.5% of vanadium, from 0% to 0.5% of niobium, from 0% to 0.5% of zirconium, at most 0.3% of nitrogen and, optionally, from 0.0005% to 0.005% of boron, optionally from 0.005% to 0.1% of titanium, optionally at least one element taken from Ca, Se, Te, Bi and Pb in contents less than 0.2%, the balance being iron and impurities resulting from smelting; the chemical composition furthermore satisfying the relationships: 1%.ltoreq.Si+Al.ltoreq.3% and 4.6.times.(%C)+1.05.times.(%Mn)+0.54.times.(%Ni)+0.66.times.(%Mo+%W/2)+0.5 .times.(%Cr)+K.gtoreq.3.8 where K=0.5 when the steel contains boron, K=0 when the steel does not contain boron.

Abstract: A method for manufacturing an alloy sheet for a shadow mask is provided which includes: (i) annealing a hot-rolled sheet containing Fe and Ni at a temperature of 910.degree. to 990.degree. C.; (ii) cold-rolling the annealed hot-rolled sheet from step (i) to produce a cold-rolled sheet; (iii) crystallization annealing of the cold-rolled sheet from step (ii); (iv) cold-rolling the annealed cold rolled sheet from step (iii); (v) finish recrystallization annealing step of the cold-rolled sheet of step (iv); (vi) finish cold-rolling of the sheet from step (v) at a cold-rolling reduction ratio R (%) satisfying the following equations: 16.ltoreq.R.ltoreq.75 and 6.38 D-133.9.ltoreq.R.ltoreq.6.38 D-51.0 wherein D is the average austenite grain size in .mu.m; (vii) softening annealing the sheet from step (vi) at a temperature of 720.degree. to 790.degree. C. for 2 to 40 minutes before press-forming and at conditions of temperature T in .degree.C. and time t in minutes which satisfy the following equation :T.gtoreq.-53.

Abstract: An Fe-Mn vibration damping alloy steel having a mixture structure of .epsilon., .alpha.' and .gamma.. The alloy steel consists of iron, manganese from 10 to 24% by weight and limited amounts of impurities. The alloy steel is manufactured by preparing an ingot at a temperature of 1000.degree. C. to 1300.degree. C. for 12 to 40 hours to homogenize the ingot and hot-rolling the homogenized ingot to produce a rolled alloy bar or plate, performing solid solution treatment on the alloy steel at 900.degree. C. to 1100.degree. C. for 30 to 60 minutes, cooling the alloy steel by air or water, and cold rolling the alloy steel at a reduction rate of greater than 0% and below 30% at around room temperature.

Abstract: A tool steel composition including, expressed by weight: 2.5% to 5.8% Cr, not more than 1.3% V, not more than 0.8% Si, with an Mo content lying in the range 0.75% to 1.75%, and not more than 0.35% Si, when the Mo content is 2.5% to 3.5%, with 0.3% to 0.4% by weight of C. Also disclosed is a method of preparing and of shaping such steels, as well as parts obtained thereby.

Abstract: A high pressure-low pressure single cylinder turbine rotor is disclosed which is characterized by being formed of a steel of a composition having, by weight, a C content of from 0.10 to 0.35%, a Si (silicon) content of not more than 0.3% (not including 0%), a Mn (manganese) content of not more than 1.0% (not including 0%), a Ni content of from 1.0 to 2.0%, a Cr (chromium) content of from 1.5 to 3.0%, a Mo content of from 0.9 to 1.3%, a V (vanadium) content of from 0.10 to 0.35%, a Nb (niobium) content of from 0.01 to 0.15%, a W content of from 0.1 to 1.5%, and the balance of Fe (iron) and inevitable impurities, the inevitable impurities having a P content of not more than 0.005%, a S content of not more than 0.001%, an As content of not more than 0.008%, a Sb content of not more than 0.004%, and a Sn content of not more than 0.008%.

Abstract: The present invention relates to a steam turbine comprising a rotor shaft integrating high and low pressure portions provided with blades at the final stage thereof having a length not less than 30 inches, wherein a steam temperature at first stage blades is 530.degree. C., a ratio (L/D) of a length (L) defined between bearings of the rotor shaft to a diameter (D) measured between the terminal ends of final stage blades is 1.4 to 2.3. This rotor shaft is composed of heat resisting steel containing by weight 0.15 to 0.4% C, not more than 0.1% Si, 0.05 to 0.25% Mn, 1.5 to 2.5% Ni, 0.8 to 2.5% Cr, 0.8 to 2.5% Mo and 0.15 to 0.35% V and, further, the heat resisting steel may contain at least one of Nb, Ta, W, Ti, Al, Zr, B, Ca, and rare earth elements.

Abstract: A thermal refiningless, hot-rolled steel exhibits impact strength in excess of 10kgf.multidot.m/cm.sup.2 and contains, expressed in terms of weight percent, 0.30-0.50% carbon, 0.15-0.60% silicon, 0.80-1.60% manganese, up to 0.02% phosphorus, up to 0.015% sulfur, 0.07-0.20% vanadium, 0.015-0.06% aluminum, 0.005-0.015% nitrogen, up to 0.0015% oxygen, the balance iron and unavoidable impurities. The steel of the above-identified property and composition is produced by casting a steel product of predetermined cross-sectional shape; heating the steel product up to a temperature of 1,100.degree.-1,250.degree. C.; hot-rolling the heated steel product at a final rolling temperature of 850.degree.1,000.degree. C.; normalizing the hot-rolled steel product at a temperature of 880.degree.-950.degree. C.; and cooling the normalized steel product down to 300.degree. C. at a cooling speed of 5.degree.-100.degree. C./min.

Abstract: This invention aims at obtaining a cold steel sheet having excellent cold formability irrespective of a high N content in order to re-utilize a scrap steel generated from scraps. A steel sheet comprising not greater than 0.1% of C, 60 to 150 ppm of N, not greater than 0.4% of Mn satisfying the relation Mn/S.gtoreq.7, not greater than 0.030% of S, not greater than 0.1% of Al and not greater than 0.08% of Ti satisfying the relation N (%)--Ti/3.42 (%).ltoreq.0.007, wherein the size of TiN in the weight at least 1/2 of the total TiN weight is 0.05 to 10 .mu.m, is obtained. When production is made by continuous annealing, Ti is added so as to satisfy the relation N (%)--Ti/3.42 (%).ltoreq.0.004% and furthermore, high temperature winding is effected in hot rolling or B is added.When production is made by box annealing, the Ti content is adjusted so as to satisfy the relation 0.002%.ltoreq.N (%)--Ti/3.42 (%).ltoreq.0.

Abstract: Rolled articles such as hot rolled or cold rolled and annealed sheet and/or strip include effective amounts of vanadium in low carbon steels to produce an improved bake hardenable product especially adapted for automotive use. The use of vanadium in the alloy steel chemistry controls bake hardenability, permits solution annealing at lower temperatures in its manufacturing sequence and specifies a composition range which is more easily cast within desired limits and causes less variation in final mechanical properties.

Abstract: Improved steel strapping and method for producing comprising adding to a steel composition of about 0.25 to about 0.34 wt. % carbon, about 1.20 to about 1.55 wt. % manganese and up to about 0.035 wt. % silicon, an addition consisting of about 0.20 to about 0.25 wt. % vanadium, or 0.35 to about 0.45 wt. % molybdenum, or about 0.35 to about 0.45 wt. % molybdenum plus about 0.12 to about 0.18 wt. % vanadium, casting, hot rolling and cold rolling the steel to strapping form and austempering the steel strapping.

Abstract: A fully killed steel has a composition that is tailored to meet a 50 KSI minimum yield strength after hot rolling and accelerated cooling. The steel has a carbon content in the range of from about 0.05 to about 0.10 percent or from about 0.15 to about 0.27 percent, from about 0.005 to about 0.020 percent titanium, from about 0.004 to about 0.015 percent nitrogen, from 0 to about 0.02 percent vanadium, and the remainder iron plus incidental impurities. The steel is continuously cast, hot rolled to plate, and cooled to a temperature of less than about 1100.degree. F. at a cooling rate lying in a cooling rate band extending from about 2.degree. to about 14.degree. F./sec at 2 inches plate thickness, from about 7.degree. to about 26.degree. F./sec at 1 inch plate thickness, and from about 13.degree. to about 45.degree. F./sec at 1/2 inch plate thickness.

Abstract: A high yield ratio-type, hot rolled high strength steel sheet excellent in both formability and spot weldability, containing not less than 5% of retained austenite, and a process for producing the same are provided. The steel sheet contains 0.05 to less than 0.15% by weight or 0.15 to less than 0.30% by weight of C, 0.5 to 3.0% by weight of Si, 0.5 to 3.0% by weight of Mn, more than 1.5 to 6.0% by weight of Si and Mn in total, not more than 0.02% by weight of P, no more than 0.01% by weight of S, and 0.005 to 0.10% by weight of Al, the balance essentially being Fe, and is composed of three phases of ferrite, bainite and retained austenite as a microstructure, and having a ratio (V.sub.F /d.sub.F) of ferrite volume fraction (V.sub.F) to ferrite grain size (d.sub.F) of not less than 20 (not less than 7 in case of 0.15 to less than 0.30% by weight of C), a volume fraction of retained austenite having grain sizes of not more than 2 .mu.

Abstract: The invention relates to a process for the production of very hard armour plates from steel slabs, wherein the slabs are hot rolled to a final thickness above 50 mm and then hardened and possibly tempered. The characterizing feature of the invention is that a continuously cast slab is produced from a steel having0.25 to 0.32% C0.05 to 0 75% Si0.10 to 1.50% Mn0.90 to 2.00% Cr0.10 to 0.70% Mo1 20 to 4 50% Ni0.01 to 0.08% Almax 0.015% Pmax 0.005% Smax 0.012% Nresidue Fe, including usual impurities,the slab then being heated to a temperature of 1150.degree. C. or higher and heated through, whereafter following cooling in air and by the spraying of its two wide sides with pressurized water, the slab is hot rolled with a surface temperature in the range of 1050.degree. to 900.degree. C. in shaping passes having an individual deformation of .epsilon..sub.h >0.1 and with a shape factor SF>0.40 to the final thickness.

Abstract: A high-strength spring steel has a high fatigue limit and is characterized by restricting the number of oxide particle inclusion having a diameter of not less than 10 .mu.m in steel to not more than 12 particles/100 mm.sup.2.

Abstract: An abrasion-resistant steel having excellent surface property consists essentially of 0.1 to 0.45 wt. % C, 0.1 to 1 wt. % Si, 0.1 to 2 wt. % Mn, 0.04 wt. % or less P, 0.04 wt. % or less S, 0.1 to 1 wt. % Ti, 0.0015 to 0.01 wt. % N, and the balance being Fe and inevitable impurities, the steel including at least 400 TiC precipitates of 0.5 .mu.m or more in particle size per 1 mm.sup.2 and the steel having Ti* of 0.05 wt. % or more and less than 0.4 wt. % the Ti* being defined by the equations of Ti*=Ti(a)-[Ti], Ti(a)=Ti-{(48/14)N+(48/32)S}, log[Ti][C]=(-10580/T)+4.38, [Ti]=4.times.[C]+{Ti(a) -4.times.C}.A method for producing an abrasion-resistant steel having excellent surface property comprising the steps of: preparing a molten steel having the composition specified above; casting continuously the molten steel to produce slab, coarse particles of TiC being precipitated in the slab; hot-working the slab to produce a hot-rolled steel sheet at 1300.degree. C. or less; and quenching the hot-rolled steel sheet.

Abstract: A steel containing predetermined components is rolled in a recrystallization temperature region or a non-recrystallization temperature region of an austenite and is subsequently subjected to repeated hot bending. Alternatively, a surface layer portion is cooled during rolling of the steel described above to an .alpha. single phase or a .gamma./.alpha. dual phase temperature region, rolling is then effected and is finished at the point of time when the surface temperature of the plate rises above an Ac.sub.3 point due to recuperative heat, and repeated bending is carried out. Still alternatively, the steel described above is rolled to a cumulative reduction ratio of at least 20% in the non-recrystallization temperature region and is then subjected to repeated bending. Further alternatively, the surface layer portion is cooled during hot rolling of the steel described above to an .alpha. single or .gamma./.alpha.

Abstract: The method makes possible the production of iron aluminide raw materials which consist of a Fe.sub.3 Al-base alloy containing 18-35% Al, 3-15% Cr, 0.2-0.5% B and/or C, and altogether 0-8% of the following alloying additives: Mo, Nb, Zr, Y and/or V, as well as iron as dominant remainder. In accordance with the invention additives are added to the melt of a known alloy, from which dispersed crystallites, dispersoids, are formed which thanks to good wettability become upon solidification, embedded in the monocrystalline phase. From the solid alloy, through hot rolling at a temperature between 650.degree. and 1000.degree. C., a fine grain structure may be generated.

Abstract: A vibration damping alloy has a mixed structure of martensite and austenite. The alloy steel is iron-based to which 14-22% by weight of manganese is added. The vibration damping alloy is manufactured by mixing electrolytic iron and manganese in a molten state. The molten mixture, containing 14-22% of manganese with the remainder of iron, is cast as an ingot. The ingot is homogenized at 1000.degree.-1300.degree. C. for 20-40 hours and then hot rolled at 900.degree.-1100.degree. C. for 20 minutes to 90 minutes. The ingot is cooled with air or water.

Abstract: New low-alloy steel compositions and rotor shafts for electric machines made from them are described. High nickel and chromium contents ensure high strength and toughness, while other components, notably silicon and other impurities, are kept low with the result that magnetic properties remain good. One aspect provides a steel with the following proportions by weight:C 0.15 to 0.3%Si <0.1%Mn <1%Ni 3 to 5%Cr >2%, <3.5%(Mo+W) 0.1 to 1.0%, W being optionalV 0.03 to 0.35%,and the remainder substantially Fe.Other aspects are also described.

Abstract: In composition of Fe-Ni alloy preferably used for lead frames in production of IC, specified amount of Be is added to the basic composition for increase in mechanical strength whilst maintaining the low thermal expansion characteristic of the conventional Fe-Ni alloys.

Abstract: An Fe-Ni alloy sheet for a shadow mask, which consists essentially of:nickel: from 34 to 38 wt. %,silicon: from 0.01 to 0.15 wt. %,manganese: from 0.01 to 1.00 wt. %, andthe balance being iron and incidental impurities.The surface portion of the alloy sheet has a silicon (Si) segregation rate, as expressed by the following formula, of up to 10%: ##EQU1## and a center-line mean roughness (Ra) of the alloy sheet satisfies the following formula:0.3 .mu.m<.ltoreq.Ra .ltoreq.0.7 .mu.m.The above-mentioned Fe-Ni alloy sheet is manufactured by preparing an Fe-Ni alloy sheet having the chemical composition and the silicon segregation rate as described above, and imparting a center-line mean roughness (Ra) which satisfies the above-mentioned formula onto the both surfaces of the alloy sheet by means of a pair of dull rolls during the final rolling of the alloy sheet for said preparation.

Abstract: In order to produce sheet possessing good forming properties, in particular for rotationally symmetrical deep-drawings, a low-carbon steel containing not more that 0.009% N is alloyed with 0.01 to 0.94% Ti and in certain cases with 0.01 to 0.06% Nb and continuously cast. The plate slabs are heated to a temperature above 1120 degrees Celsius, rolled to obtain a hot strip above the Ar.sub.3 point, and would at 520.+-.100 degrees Celsius. After cold rolling to the desired fine sheet thickness, the steel strip is annealed by recrystallizaiton, skin-passes and made into sheets.

Abstract: A bake hardening cold-rolled steel sheet which has good bake hardenability, good dent resistance, and low yield ratio which contributes to the shape-fixability of the steel sheet. The steel is suitable for the outer panel of an automobile. The process for manufacturing the steel sheets includes the following steps:(1) preparing a melting steel which contains 0.02 to 0.06% carbon by weight, 0.60% to 1.40% manganese by weight, 0.5% silicon by weight at most, 0.1% phosphorus by weight at most, 0.1% aluminum by weight at most, 0.01% nitrogen by weight at most, 0.1% titanium by weight at most, and 50 ppm of boron at most;(2) preparing steel ingots by continuous casting the melting steel;(3) hot rolling the steel ingots to hot-rolled bands;(4) coiling the hot-rolled bands at temperature ranging from 560.degree. C. to 720.degree. C.;(5) after cold rolling, soaking the steel sheets at temperature ranging from 780.degree. C. to 900.degree. C.

Abstract: Air-hardenable steels of duplex bainite/martensite microstructure consisting essentially of 0.10 to 0.7% C, 0.1 to 2% Si, 2.1 to 3.5% Mn, 0.0005 to 0.005% B, up to 3.5% Cr and preferably containing Cr in amount of at least 0.1%, balance Fe except for incidental impurities. Optional elements are up to 1.5% W, 1.0% Mo, 0.15% V, 0.2% S, 0.1% Ca, 0.1% Pb, 0.1% Ti and 0.2% total rare earths. At least 1.0% Cr is especially preferred and if below such amount, total Mn and Si is at least 3% and in such case, if C is under 0.47%, at least 0.6% Si is present. The steels are hardenable to R.sub.c 2o to R.sub.c 58 and have a hardenable diameter in the range between 35 mm and 80 to 100 mm by air-cooling only, together with good strength, toughness and fatigue- and wear-resistance.