Heat treatment No.	Quenching temperature, ˚C	The first cryogenic treatment, QC	The first tempering, QCT	The second cryogenic treatment, QCTC	The second tempering, QCTCT	Volume percentage of retained austenite	Widths of martensite laths, mm
Heat treatment No.	Quenching temperature, ˚C	The first cryogenic treatment, QC	The first tempering, QCT	The second cryogenic treatment, QCTC	The second tempering, QCTCT	Volume percentage of retained austenite	Widths of martensite laths, mm
Quenching	1040˚C/1h					16.9	-
C	1040˚C/1h	−75˚C/2h				4.1	255
D	1040˚C/1h	−75˚C/2h	510˚C/2h			3.3	200
E	1040˚C/1h	−75˚C/2h	510˚C/2h	−75˚C/2h		2.7	76
F	1040˚C/1h	−75˚C/2h	510˚C/2h	−75˚C/2h	510˚C/2h	2.5	66