Abstract An elongated steel workpiece is quickly heat treated in a single heat treatment, by passing it between spaced electrodes and applying a current to the steel between the electrodes thereby to heat it above the austenitic transformation temperature at a heating rate of at least 50* per second, preferably 200* to 100,000*C. per second, holding it at such annealing temperature for at most 300 seconds, preferably 0.04 to 3 seconds, so as to recrystallize the ferrite while dissolving substantially none of the carbides. The annealing temperature is no more than 85% and preferably 50-75% of the melting temperature of the steel in Kelvin degrees. The material is then quenched below the austenitic transformation temperature to prevent austenitic transformation and carbide precipitation.
A PROCESS FOR THE RAPID HEAT TREATMENT OF COLD WORKED STEEL, COMPRISING HEATING THE STEEL AT THE RATE OF AT LEAST 50*C PER SECOND TO A TEMPERATURE ABOVE THE AUSTENITIC TRANSFORMATION TEMPERATURE, HOLDING THE STEEL AT SAID TEMPERATURE FOR A TIME AT MOST 300 SECONDS TO RECRYSTALLIZED THE FERRITE WITHOUT SUBSTANTIAL DISSOLUTION OF THE CARBIDES PRESENT IN THE STEEL, AND QUENCHING THE STEEL FROM SAID TEMPERATURE TO A TEMPERATURE BELOW THE AUSTENITIC TRANSFORMATION TEMPERATURE TO PREVENT THE OCCURENCE OF AUSTENITIC TRANSFORMATION AND CARBODE PRECIPITATION.
Claim 2
Dependent Claim
84 words
A PROCESS FOR THE RAPID HEAT TREATMENT OF COLD WORKED STEEL, COMPRISING HEATING THE STEEL AT THE RATE OF AT LEAST 50*C PER SECOND TO A TEMPERATURE ABOVE THE AUSTENITIC TRANSFORMATION TEMPERATURE, HOLDING THE STEEL AT SAID TEMPERATURE FOR A TIME AT MOST 300 SECONDS TO RECRYSTALLIZED THE FERRITE WITHOUT SUBSTANTIAL DISSOLUTION OF THE CARBIDES PRESENT IN THE STEEL, AND QUENCHING THE STEEL FROM SAID TEMPERATURE TO A TEMPERATURE BELOW THE AUSTENITIC TRANSFORMATION TEMPERATURE TO PREVENT THE OCCURENCE OF AUSTENITIC TRANSFORMATION AND CARBODE PRECIPITATION.
Claim 3
Dependent Claim
16 words
A process as claimed in claim 1, in which said heating rate is 200*-100,000*C. per second.
Claim 4
Dependent Claim
14 words
A process as claimed in claim 1, said time being 0.04 to 3 seconds.
Claim 5
Dependent Claim
25 words
A process as claimed in claim 1, said temperature being no more than 85% of the melting temperature of the steel measured in Kelvin degrees.
Claim 6
Dependent Claim
22 words
A process as claimed in claim 1, said temperature being 50-75% of the melting temperature of the steel measured in Kelvin degrees.
Claim 7
Dependent Claim
56 words
A process as claimed in claim 1, in which said steel is in the form of an elongated workpiece and said heating is performed by passing said workpiece between and in electrical contact with a spaced pair of electrodes, and passing a current through said workpiece between said electrodes thereby electrically resistively to heat said workpiece.