High strength steels, processes for making same, and materials resulting therefrom

Abstract

A method is disclosed for Flash Process heat treating lean alloyed steels in strips, sheets, bars, plates, wires, tubes, profiles, work pieces and the like which are converted into multi-phase, multi chemistry armor and advanced high strength steel produced with a minimum of cost, time and effort. The resulting material is a high performance armor with the ability to prevent penetration by a 0.30-caliber M2 armor piercing bullet shot at a 30 degree obliquity, from perpendicular to the plate. Stopping velocity of 2232 feet per second.

What is claimed is: 
     
         1 . A method for treating a steel article to form a high tensile strength, high hardness, and ductile alloy comprising:
 (a) providing a steel article having a material thickness no greater than 1.0 inches (25.4 mm), having an initial microstructure of at least ferrite and/or pearlite and/or spheroidized carbides, being in any condition such as cold rolled to full hard, ¾ hard, ½ hard, ¼ hard, or annealed, and having a chemistry of, by weight, carbon between 0.08 and 0.55%, manganese up to 35.0%, carbide forming elements such as chromium, molybdenum, silicon, titanium, vanadium, columbium, tantalum, cobalt, aluminum, and tungsten up to 25% total weight in combination, nickel less than 8.0%, phosphorus less than 1.0%, and balance iron and other elements and compounds in making steels;   (b) optionally preheating the provided steel article to not more than 700° C. with no temporal limits required on the duration of preheating;   (c) heating the provided steel article from its starting temperature below 700° C. to a peak temperature of at least 1000° C., but not more than 1400° C., at a rate of 30° C. to 3000° C. per second, with a total heating time of less than ten seconds employing induction, radiant, conduction, convection, resistance, or other heating methods;   (d) holding the heated steel article at the selected peak temperature range for less than ten seconds acknowledging the temperature of the steel may remain constant or decrease due to the lack of further heat input during this time;   (e) quenching the heated steel article from the peak temperature range to below 500° C. at a temperature rate reduction of between 100° C. and 3000° C./sec in less than 10 seconds employing quench media such as water, aqueous solutions, oils, molten salts/metals, forced air, or other quenching methods;   (f) optionally interrupting the quenching of the steel article and holding the temperature of the quenched steel article at a temperature between 150° C. and 500° C. for less than thirty minutes;   (g) further cooling of the steel article to below the steel's bainitic and martensitic finish temperatures to form a steel article having at least 5% bainite and at least 60% martensite by volume fraction, a yield strength of at least 1240 MPa (180 KSl), and a tensile strength of at least 1400 MPa (203 KSl).   (h) optionally removing residual quench media from the surface of the quenched steel article;   (i) optionally tempering the quenched steel article, by methods individually or in combination of induction, radiant, conduction, convection, resistance, or liquefied solution heating, or other heating methods at a temperature from 100° C. to 300° C. for less than thirty minutes;   (j) optionally, the steel article can be controlled to have at least 10% to 25% bainite or more; and   (k) resulting in a steel article that must have a velocity 50 th  percentile (V 50 ) protection ballistic limit at 30° obliquity angle at least 2500 feet per second (fps) (762 m/s) with a 0.30 caliber armor piercing round for a thickness of 0.25 inches (6.35 mm) and which other thicknesses will have a passing V50 armor performance velocity as defined by US Army MIL DTL 32332 Class 1.   
     
     
         2 . A method for treating a steel article to form a high tensile strength, high hardness, and ductile alloy to produce Ultra Hard Armor Class 1 comprising:
 (a) providing a steel article having a material thickness no greater than 1.0 inches (25.4 mm), having an initial microstructure of at least ferrite and/or pearlite and/or spheroidized carbides, being in any condition such as cold rolled to full hard, ¾ hard, ½ hard, ¼ hard, or annealed, and having a chemistry of, by weight, carbon between 0.35 and 0.45%, manganese less than 1.0%, carbide forming elements such as chromium, molybdenum, silicon, titanium, vanadium, columbium, tantalum, cobalt, aluminum, and tungsten up to 2.5% total weight in combination, balance iron and other elements and compounds in making steels;   (b) optionally preheating the provided steel article to not more than 700° C. with no temporal limits required on the duration of preheating;   (c) heating the provided steel article from its starting temperature below 700° C. to a peak temperature of at least 1000° C., but not more than 1400° C., at a rate of 100° C. to 3000° C. per second, with a total heating time of less than ten seconds employing induction, radiant, conduction, convection, resistance, or other heating methods;   (d) holding the heated steel article at the selected peak temperature range for less than ten seconds acknowledging the temperature of the steel may remain constant or decrease due to the lack of further heat input during this time;   (e) quenching the heated steel article from the peak temperature range to below 100° C. at a temperature rate reduction of between 100° C. and 3000° C./sec in less than 10 seconds employing quench media such as water, aqueous solutions, oils, molten salts/metals, forced air, or other quenching methods;   (f) further cooling of the steel article to below the steel's bainitic and martensitic finish temperatures to form a steel article having at least 5% bainite and at least 60% martensite by volume fraction, a yield strength of at least 1400 MPa (203 KSl), and a tensile strength of at least 1800 MPa (261 KSl);   (g) optionally removing residual quench media from the surface of the quenched steel article;   (h) optionally tempering the quenched steel article, by methods individually or in combination of induction, radiant, conduction, convection, resistance, or liquefied solution heating or other heating methods, at a temperature from 100° C. to 300° C. for less than thirty minutes;   (i) optionally, the steel article can be controlled to have at least 10% to 25% bainite or more; and   (j) resulting in a steel article that must have a velocity 50 th  percentile (V 50 ) protection ballistic limit at 30° obliquity angle at least 2500 feet per second (fps) (762 m/s) with a 0.30 caliber armor piercing round for a thickness of 0.25 inches (6.35 mm) and which other thicknesses will have a passing V50 armor performance velocity as defined by US Army MIL DTL 32332 Class 1.   
     
     
         3 . A method for treating a steel article to form a high tensile strength, high hardness, and ductile alloy to produce Ultra Hard Armor Class 2 comprising:
 (a) providing a steel article having a material thickness no greater than 1.0 inches (25.4 mm), having an initial microstructure of at least ferrite and/or pearlite and/or spheroidized carbides, being in any condition such as cold rolled to full hard, ¾ hard, ½ hard, ¼ hard, or annealed, and having a chemistry of, by weight, carbon between 0.43 and 0.53%, manganese less than 1.0%, carbide forming elements such as chromium, molybdenum, silicon, titanium, vanadium, columbium, tantalum, cobalt, aluminum, and tungsten up to 1.5% total weight in combination, balance iron and other elements and compounds in making steels;   (b) optionally preheating the provided steel article to not more than 700° C. with no temporal limits required on the duration of preheating;   (c) heating the provided steel article from its starting temperature below 700° C. to a peak temperature of at least 1000° C., but not more than 1400° C., at a rate of 100° C. to 3000° C. per second, with a total heating time of less than ten seconds employing induction, radiant, conduction, convection, resistance, or other heating methods;   (d) holding the heated steel article at the selected peak temperature range for less than ten seconds acknowledging the temperature of the steel may remain constant or decrease due to the lack of further heat input during this time;   (e) quenching the heated steel article from the peak temperature range to below 100° C. at a temperature rate reduction of between 100° C. and 3000° C./sec in less than 10 seconds employing quench media such as water, aqueous solutions, oils, molten salts/metals, forced air, or other quenching methods;   (f) further cooling of the steel article to below the steel's bainitic and martensitic finish temperatures to form a steel article having at least 5% bainite and at least 60% martensite by volume fraction, a yield strength of at least 1400 MPa (203 KSl), and a tensile strength of at least 1800 MPa (261 KSl);   (g) optionally removing residual quench media from the surface of the quenched steel article;   (h) optionally tempering the quenched steel article, by methods individually or in combination of induction, radiant, conduction, convection, resistance, or liquefied solution heating or other heating methods, at a temperature from 100° C. to 300° C. for less than thirty minutes;   (i) optionally, the steel article can be controlled to have at least 10% to 25% bainite or more; and   (j) resulting in a steel article that must have a velocity 50 th  percentile (V 50 ) protection ballistic limit at 30° obliquity angle at least 2700 feet per second (fps) (762 m/s) with a 0.30 caliber armor piercing round for a thickness of 0.25 inches (6.35 mm) and which other thicknesses will have a passing V50 armor performance velocity as defined by US Army MIL DTL 32332 Class 2.   
     
     
         4 . A method for treating a radially symmetric steel article to form a high tensile strength, high hardness, and ductile alloy, comprising:
 (a) providing a radially symmetric steel article in a bowl-like shape having a material thickness no greater than 0.5 inches (12.7 mm), having an initial microstructure of at least ferrite and/or pearlite and/or spheroidized carbides, being in any condition such as cold rolled to full hard, ¾ hard, ½ hard, ¼ hard, or annealed, and having a composition of, by weight, carbon between 0.05 and 0.55%, manganese up to 35.0%, carbide forming elements such as chromium, molybdenum, silicon, titanium, vanadium, columbium, tantalum, cobalt, aluminum, and tungsten up to 25% total weight in combination, nickel less than 8.0%, phosphorus less than 1.0%, and balance iron and other elements and compounds in making steels;   (b) placing, fixturing, and holding the radially symmetric steel article in a rotating heat/quench apparatus with integral induction heating coils and quench apparatus;   (c) rotating the steel article at a rate of at least 6 revolutions per minute   (d) optionally preheating the provided rotating radially symmetric steel article to not more than 700° C. with no temporal limits on the duration of preheating in the rotating heat/quench apparatus;   (e) heating the provided rotating radially symmetric steel article from its starting temperature below 700° C. to a peak temperature of at least 1000° C., but not more than 1400° C., at a rate of 30° C. to 3000° C. per second, with a total heating time of less than ten seconds employing induction, radiant, conduction, convection, resistance, or other heating methods known to those skilled in the art;   (f) holding the rotating heated radially symmetric steel article at the selected peak temperature range for less than ten seconds acknowledging the temperature of the steel may remain constant or decrease due to the lack of further heat input during this time;   (g) quenching the rotating heated radially symmetric steel article, while it rotates or remains in a static position after ceasing rotation, from the peak temperature range to below the steel's bainitic and martensitic finish temperatures at a temperature rate reduction of between 100° C. and 3000° C./sec in less than 10 seconds employing quench media such as water, aqueous solutions, oils, molten salts/metals, forced air, or other quenching methods known to those skilled in the art to form a radially symmetric steel article having at least 5% bainite and at least 60% martensite by volume fraction, a yield strength of at least 600 MPa, and a tensile strength of at least 800 MPa.   (h) removing residual quench media from the surface of the quenched radially symmetric steel article;   (i) optionally rotating the steel article at a rate of at least 6 revolutions per minute   (j) optionally tempering the quenched steel article, by methods individually or in combination of induction, radiant, conduction, convection, resistance, or liquefied solution heating, at a temperature from 100° C. to 300° C. for less than thirty minutes;   (k) optionally, the steel article can be controlled to have at least 10% to 25% bainite or more   (l) optionally performing secondary forming operations such as stamping, flanging, trimming, piercing, and other methods of forming steel known to those skilled in the art to create a finished Flash Process heat/quenched steel article.   
     
     
         5 . A method for treating a stainless steel article to form a high tensile strength, high hardness, and ductile alloy to produce stainless High Hard Armor comprises:
 (a) providing a stainless steel article having a material thickness no greater than 1.0 inches (25.4 mm), having an initial microstructure of at least ferrite and/or pearlite and/or spheroidized carbides, being in any condition such as cold rolled to full hard, ¾ hard, ½ hard, ¼ hard, or annealed, and having a chemistry of, by weight, carbon between 0.10 and 0.40%, manganese less than 1.0%, chromium between 12.0 and 14.0%, other carbide forming elements such as molybdenum, silicon, titanium, vanadium, columbium, tantalum, cobalt, aluminum, and tungsten up to 5% total weight in combination, balance iron and other elements and compounds in making steels;   (b) optionally preheating the provided stainless steel article to not more than 700° C. with no temporal limits required on the duration of preheating;   (c) heating the provided stainless steel article from its starting temperature below 700° C. to a peak temperature of at least 1000° C., but not more than 1400° C., at a rate of 100° C. to 3000° C. per second, with a total heating time of less than ten seconds employing induction, radiant, conduction, convection, resistance, or other heating methods known to those skilled in the art;   (d) holding the heated stainless steel article at the selected peak temperature range for less than ten seconds acknowledging the temperature of the steel may remain constant or decrease due to the lack of further heat input during this time;   (e) quenching the heated stainless steel article from the peak temperature range to below 100° C. at a temperature rate reduction of between 100° C. and 3000° C./sec in less than 10 seconds employing quench media such as water, aqueous solutions, oils, molten salts/metals, forced air, or other quenching methods known to those skilled in the art;   (f) further cooling of the stainless steel article to below the steel's bainitic and martensitic finish temperatures to form a stainless steel article having at least 5% bainite and at least 60% martensite by volume fraction, a yield strength of at least 1400 MPa (203 KSl), and a tensile strength of at least 1800 MPa (261 KSl).   (g) optionally removing residual quench media from the surface of the quenched stainless steel article;   (i) optionally tempering the quenched stainless steel article, by methods individually or in combination of induction, radiant, conduction, convection, resistance, or liquefied solution heating or other heating methods known to those skilled in the art, at a temperature from 100° C. to 300° C. for less than thirty minutes;   (j) optionally, the stainless steel article can be controlled to have at least 10% to 25% bainite or more   (k) resulting in a stainless steel article that must have a velocity 50 th  percentile (V 50 ) protection ballistic limit at 30° obliquity angle at least 2197 feet per second (fps) (762 m/s) with a 0.30 caliber armor piercing round for a thickness of 0.245 inches (6.25 mm) and which other thicknesses will have a passing V50 armor performance velocity as defined by US Army MIL DTL 46100E.