Microtreatment of iron-based alloy, apparatus and method therefor and articles resulting therefrom

Abstract

Iron-based alloys and articles in strips, sheets, workpieces and the like are converted into high strength steel with a minimum of cost, time and effort, including producing dual phase materials. This is achievable by extremely rapid micro-treating of low, medium, and high carbon iron-based alloys and articles by rapid heating and rapid cooling at least a portion of the alloy/article. This heating step involves nearly immediately heating the iron-based alloy to a selected temperature above its austenite conversion temperature. Then, the alloy is immediately quenched, also at an extremely fast rate, on at least a portion of the iron-based alloy in a quenching unit adjacent the heating unit. This procedure forms high strength alloy in a desired area, depending upon where the treatment was performed.

What is claimed is: 
     
         1 . A method for rapidly micro-treating an iron-based alloy to form at least one phase of a high strength alloy, said method comprising the steps of:
 providing an iron-based alloy having a first micro-structure with an austenite conversion temperature, said first microstructure being capable of being transformed to an iron-based alloy having a second micro-structure;   rapidly heating the iron-based alloy to a selected temperature above its austenite conversion temperature; and   immediately quenching at least a portion of the iron-based alloy in a quenching unit adjacent the heating unit to form at least one phase of a high strength alloy upon being rapidly heated to said selected temperature and then being rapidly quenched.   
     
     
         2 . The method of  claim 1 , wherein the resulting high strength iron-based alloy includes at least one portion of a material including at least 55% of a second microstructure selected from the group consisting of bainite, coalesced bainite, ferrite, martensite, pearlite, austenite, and Colascite. 
     
     
         3 . The method of  claim 1 , wherein the iron-based alloy is a low carbon steel which contains carbon in a range of between 0.001 percent carbon by weight (wt %) to 4 percent carbon by weight (wt %). 
     
     
         4 . The method of  claim 1 , wherein the iron-based alloy is in a form selected from the group consisting of wire, strips, sheets, any 2-dimensional continuous cross-section, 3-dimensionally variable workpieces, articles, hollow tubes and combinations thereof. 
     
     
         5 . The method of  claim 1 , further comprising an additional step of pre-heating the iron-based alloy to a temperature below the austenitic conversion temperature in a range of about 315° C. to about 705° C. 
     
     
         6 . The method of  claim 1 , wherein the heating is accomplished by a heating unit selected from the group consisting of gas torches, electric resistance heaters, fluidized beds, electric furnaces, plasma furnaces, microwave ovens, open environment propane forges, gas fired units, solid fuels, high temperature salt baths, torches and any combination thereof. 
     
     
         7 . The method of  claim 6 , wherein the heating unit transfers heat by a way selected from the group consisting of radiation, conduction, convection, induction and any combination thereof. 
     
     
         8 . The method of  claim 1 , wherein the rate of heating is from 260° C./sec to 3000° C./sec. 
     
     
         9 . The method of  claim 6 , wherein the heating unit includes propane gas torch heads. 
     
     
         10 . The method of  claim 1 , wherein the selected temperature is at least between about 723° C. to about 1450° C. 
     
     
         11 . The method of  claim 1 , wherein the selected temperature is at least between about 900° C. to about 1300° C. 
     
     
         12 . The method of  claim 1 , wherein the step of quenching the heated alloy is accomplished by a quenching means selected from the group consisting of water, water-containing aqueous solutions, oil, molten salt, brine solutions, gases including air, powders and any combination thereof. 
     
     
         13 . The method of  claim 1  in which quenching is accomplished at a rate of 315° C./sec to 6,000° C./sec. 
     
     
         14 . Apparatus for micro-treating a low, medium, or high carbon iron-based alloy workpiece of a first microstructure having an austenitic conversion temperature to form at least one phase of a high strength alloy, comprising:
 a micro-heating unit for rapidly heating at least a portion of the low carbon iron-based alloy workpiece to a selected temperature, said micro-heating unit being capable of rapidly heating the workpiece to a temperature above the austenitic conversion temperature;   a quenching unit positioned adjacent the micro-heating unit for rapidly quenching the heated iron-based alloy; and   a control unit for controlling and transporting the iron-based alloy workpiece through the micro-heating unit and the quenching unit during the rapid heating and rapid quenching to form at least one phase of a high strength alloy upon being rapidly heated to said selected temperature and then being rapidly quenched.   
     
     
         15 . The apparatus of  claim 14 , wherein the selected temperature is at least between about 723° C. to about 1450° C. 
     
     
         16 . The apparatus of  claim 14 , wherein the heating unit is selected from the group consisting of electric resistance heaters, fluidized beds, electric furnaces, plasma furnaces, microwave ovens, open environment propane forges, gas fired units, solid fuels, high temperature salt baths, torches and any combination thereof. 
     
     
         17 . The apparatus of  claim 14 , wherein the heating unit is selected from the group consisting of stationary heating heads, heated warm forms, heated sheet stamp dies, heated conventional dies, heated progressive dies, heated line dies, heated roll forming dies, heated four slide dies, heated hydroforming units, side-to-side movable heaters, hinged movable heaters, heated environment pressure form units, and combinations therefore. 
     
     
         18 . The apparatus of  claim 14 , wherein the quenching unit adapts a quenching means selected from the group consisting of water, water-containing aqueous solutions, oil, molten salt, brine solutions, air, and powders. 
     
     
         19 . The apparatus of  claim 14 , wherein the heating unit includes propane torches having blaster nozzles and a valve control operably connected to said blaster nozzles for effecting heating control. 
     
     
         20 . The apparatus of  claim 14 , wherein the quenching unit includes a water bucket with water therein as a quenching medium to cool the low carbon iron-based alloy and a chiller connected to the water bucket to keep the water at a suitable temperature. 
     
     
         21 . The apparatus of  claim 14 , further comprising a heat resistant insulator located between the heating unit and quenching unit to insulate the heating unit from the quenching unit and to straighten the moving low carbon iron-based alloy while it is being heated and quenched. 
     
     
         22 . Apparatus for micro-treating an article made of a low, medium, or high carbon iron-based alloy having an austenitic conversion temperature to form a high strength steel article, comprising:
 a movable head heating unit having a rapid heating rate for heating the carbon iron-based alloy to a selected temperature below its;   a quenching unit positioned adjacent the heating unit for rapidly quenching the heated low carbon iron-based alloy;   spaced first and second tensioning units positioned on opposite sides of said heating and quenching units for moving said low carbon iron-based alloy article through said heating and quenching units, and   a computer control unit for controlling and adjusting the feed rate of the first tensioning unit, the draw rate of the second tensioning unit, the heating rate of the heating unit and the cooling rate of the quenching unit, whereby the low carbon iron-based alloy has a varying thickness.   
     
     
         23 . The apparatus of  claim 22 , wherein the selected temperature is at least between about 1040° C. to about 1270° C. 
     
     
         24 . The apparatus of  claim 22 , wherein the movable heating unit is selected from the group consisting of electric resistance heaters, fluidized beds, electric furnaces, plasma furnaces, microwave ovens, open environment propane forges, gas fired units, solid fuels, high temperature salt baths, torches and any combination thereof. 
     
     
         25 . The apparatus of  claim 22 , wherein the movable heating unit includes propane torches having blaster nozzles and a valve control operably connected to said blaster nozzles for effecting heating control. 
     
     
         26 . The apparatus of  claim 22 , wherein the quenching unit adapts a quenching means selected from the group consisting of water, water-containing aqueous solutions, oil, molten salt, brine solutions, air, and powders. 
     
     
         27 . The apparatus of  claim 22 , wherein the quenching unit includes a water bucket with water therein as a quenching medium to cool the low carbon iron-based alloy and a chiller connected to the water bucket to keep the water bucket at suitable temperature. 
     
     
         28 . The apparatus of  claim 22 , further comprising a heat resistant insulator located between the heating and quenching units to insulate the heating unit from the quenching unit and to straighten the moving strip steel while it is being heated and quenched. 
     
     
         29 . The apparatus of  claim 22 , wherein the first and second tensioning units are selected from the group consisting of drawing rollers, drive capstans, and elongation drives. 
     
     
         30 . Apparatus for micro-treating an iron-based alloy workpiece having an austenitic conversion temperature, comprising:
 a set of gas fired torches having a heating rate of 420° C. to 4,000° C. per second for heating the iron-based alloy workpiece to a first selected temperature above the austenitic conversion temperature;   a water cooling unit connected to a chiller to maintain an ambient temperature water, said unit being positioned adjacent the gas fired torches for rapidly quenching the heated iron-based alloy;   spaced first and second set of tensioning rollers positioned on opposite sides of the gas fired torches and the water bucket for moving said heated iron-based alloy workpiece through the gas fired torches and the water bucket,   a heat resistant insulator located between the gas fired torches and the water bucket to insulate the heating unit from the quenching unit and to straighten the moving the iron-based alloy workpiece while heated and quenched; and   a control unit for controlling the heating rate of the gas fired torch and the cooling rate of the water bucket, whereby the iron-based alloy forms into high strength steel.   
     
     
         31 . The apparatus of  claim 30 , wherein the first selected temperature is at least between about 1040° C. to about 1270° C. 
     
     
         32 . The apparatus of  claim 30 , wherein the set of gas fired torches including propane torches have blaster nozzles and a valve control operably connected to said blaster nozzles for effecting heating control. 
     
     
         33 . The apparatus of  claim 30 , wherein the water cooling unit includes a water bucket with water therein to quench the heated iron-based alloy and a water holding reservoir to collect additional water from the water bucket. 
     
     
         34 . The apparatus of  claim 30 , wherein the first and second set of tensioning rollers are hydraulic pressure powered. 
     
     
         35 . The apparatus of  claim 30 , wherein the heat resistant insulator includes a ceramic plate and a carbon sheet wrapping around the ceramic plate. 
     
     
         36 . The apparatus of  claim 30 , wherein the control unit is computer controlled. 
     
     
         37 . A method of making a single layer automobile panel, comprising:
 providing a micro-treated integral single layer steel sheet with bainite formed in a portion thereof, and the sheet being made of varying thicknesses by heating up to a selected temperature and immediately quenching under various tension; and   stamping the steel sheet to form a door panel having a front pillar and a rear pillar,   
       whereby the front pillar and rear pillar of the automobile panel includes sufficient bainite formed therein to increase strength and formability of the front and rear pillars. 
     
     
         38 . The method of  claim 37 , wherein the selected temperature is at least between about 1040° C. to about 1270° C.