Abstract: A method for manufacturing a steel article having a high magnetic permeability and a low coercive force, comprising the steps of: heating a material consisting essentially of:carbon: from 0.02 to 0.08 wt. %,manganese: from 0.05 to 0.49 wt. %, andthe balance being iron and incidental impurities, to a temperature of at lest 1,000.degree. C.; then hot-working the thus heated material at a finishing temperature of at least 1,000.degree. C. to prepare a steel article and then cooling the thus prepared steel article to a temperature of up to 500.degree. C. at a cooling rate of up to 0.5.degree. C./second; thereby causing crystal grains of the steel article to grow to a grain size of at least 50 .mu.m to impart a high magnetic permeability and a low coercive force to the steel article.

Abstract: A method for manufacturing a steel article having a high toughness and a high strength, which comprises the steps of:using a material comprising:carbon : from 0.020 to 0.049 wt. %,silicon : from 0.10 to 1.00 wt. %,manganese : from 1.00 to 3.50 wt. %,chromium : from 0.50 to 3.50 wt. %,where the total amount of manganese and chromium being from 2.50 to 6.00 wt. %,aluminum : from 0.01 to 0.05 wt. %,boron : from 0.0003 t6o 0.0030 wt .%,titanium : from 0.005 to 0.030 wt. %, andthe balance being iron and incidental impurities, where, the amount of nitrogen as one of the incidental impurities being up to 0.006 wt. %;heating the material to the austenitization temperature region;hot-working the material in the austenitization temperature region to prepare a steel article; andcooling the steel article thus prepared from the austenization temperature region to a temperature of or lower than 300.degree. C. at a cooling rate of from 2 to 100.degree. C.

Abstract: A method for manufacturing a steel article having a high toughness and a high strength, which comprises the steps of:using a material comprising:carbon: from 0.020 to 0.049 wt. %,silicon: from 0.10 to 1.00 wt. %,manganese: from 1.00 to 3.50 wt. %,chromium: from 0.50 to 3.50 wt. %,where the total amount of manganese and chromium being from 2.50 to 6.00 wt. %,vanadium: from 0.02 to 0.20 wt. %,aluminum: from 0.01 to 0.05 wt. %,andthe balance being iron and incidental impurities, where, the amount of nitrogen as one of the incidental impurities being up to 0.006 wt. %;heating the material to the austenization temperature region;hot-working the material in the austenization temperature region to prepare a steel article; andcooling the steel article thus prepared from the austenization temperature region to a temperature of or lower than 300.degree. C. at a cooling rate of from 2.degree. to 100.degree. C./second, thereby imparting a high toughness and a high strength to the steel article.

Abstract: An iron-based shape-memory alloy excellent in a shape-memory property, a corrosion resistance and a high-temperature oxidation resistance, consisting essentially of:chromium: from 5.0 to 20.0 wt. %,silicon: from 2.0 to 8.0 wt. %,at least one element selected from the group consisting of:manganese: from 0.1 to 14.8 wt. %,nickel: from 0.1 to 20.0 wt. %,cobalt: from 0.1 to 30.0 wt. %,copper: from 0.1 to 3.0 wt. %, andnitrogen: from 0.001 to 0.400 wt. %,whereNi+0.5 Mn+0.4 Co+0.06 Cu+0.002 N.gtoreq.0.67 (Cr+1.2 Si)-3,and the balance being iron and incidental impurities.

Abstract: An iron-based shape-memory alloy excellent in a shape-memory property and a corrosion resistance, consisting essentially of:______________________________________ chromium: from 0.1 to 5.0 wt. %, silicon: from 2.0 to 8.0 wt. %, manganese: from 1.0 to 14.8 wt. %, at least one element selected from the group consisting of: nickel: from 0.1 to 20.0 wt. %, cobalt: from 0.1 to 30.0 wt. %, copper: from 0.1 to 3.0 wt. %, and nitrogen: from 0.001 to 0.400 wt. %, where, Ni + 0.5 Mn + 0.4 Co + 0.06 Cu + 0.002 N .gtoreq. 0.67 (Cr + 1.2 Si), and the balance being iron and incidental impurities.

Abstract: A steel which is excellent in mechanical properties after a warm working process is produced by specifying a chemical composition as claimed, subjecting the steel to a controlled rolling under conditions at temperatures of not more than 900.degree. C. and accumulated reduction of more than 30%, leaving it, after the controlled rolling, as it is in the air or performing it to an accelerated cooling wherein the steel is cooled at rate between the air cooling and 100.degree. C./sec until temperatures where a transformation finishes, subsequently reheating the steel to ranges between 400.degree. C. and 750.degree. C., and carrying out the warm working thereon instantaneously or after the air cooling at the temperatures between 250.degree. C. and 750.degree. C.

Abstract: The steel plate having a high tensile strength is manufactured from a steel consisting essentially of 0.04-0.16% by weight of C, 0.02-0.50% by weight of Si, 0.4-1.2% by weight of Mn, 0.2-5.0% by weight of Ni, 0.2-1.5% by weight of Cr, 0.2-1.0% by weight of Mo, 0.01-0.10% by weight of acid soluble Al, 0.03-0.15% by weight of one or more of V, Ti and Nb, 0.015% or less by weight of P, 0.006% or less by weight of S and the balance of iron and inherent impurities. The steel is heated to a temperature above a temperature at which carbo-nitrides of V and Nb and carbides of Ti become complete solid solution state, rolled with total reduction of 40% or more below 950.degree. C., quenched by simultaneous cooling immediately after completion of the rolling from a temperature above (A.sub.3 -50).degree.C. and tempered at a temperature lower than Ac.sub.1 temperature.