1. Slightly higher tempering temperature may be applicable and/or
2. Double tempering may be applicable. The second tempering temperature shall be lower than the first tempering temperature; then air cool to ambient temperature.
I believe the low impact test absorbing energy is induced by high mechanical properties.
Normally the mechanical properties and impact test absorbing energy values after heat treatment have a balloon effect. That is, the increased mechanical properties produce the decreased impact absorbing energy and the increased impact absorbing energy produces the decreased mechanical properties.
[Required Properties of SCPL31 in JIS G5152]
Min. impact test absorbing energy (mean/ min. one) : 21J/17J at -100C
MSTS : 480 N/mm²
MSYS : 275 N/mm²
1. Slightly higher tempering temperature may be applicable and/or
2. Double tempering may be applicable. The second tempering temperature shall be lower than the first tempering temperature; then air cool to ambient temperature.
I believe the low impact test absorbing energy is induced by high mechanical properties.
Normally the mechanical properties and impact test absorbing energy values after heat treatment have a balloon effect. That is, the increased mechanical properties produce the decreased impact absorbing energy and the increased impact absorbing energy produces the decreased mechanical properties.
[Required Properties of SCPL31 in JIS G5152]
Min. impact test absorbing energy (mean/ min. one) : 21J/17J at -100C
MSTS : 480 N/mm²
MSYS : 275 N/mm²