Proper Ac3 formula

[Dalinus]

Hello,

Our customer demands Ac3 value for his final heat treatment of our castings. We asked him according to which formula, although the material chemistry is his, he wants it from us.

Can anyone guide me, which of "dozens" Ac3 formulas could be used for low alloyed steel with the folowing chemistry:

C 0,49-0,54%
Mn 0,40-0,60%
Si 1,00-1,30%
Cr 0,80-1,00%
Ni 1,00-1,20%
Mo 0,40-0,50%
P max 0,018%

I used some formula (908-224*C-34,4*Mn+30,5*Si-23*Ni+37,9*V+43,9*P, cant remember the origin) and Ac3 is in range 771-809°C.

Is there any standard for Ac3 calculation(like ASTM A255 for DI)?


Dalin

 

[metengr]

For steels where carbon content is below 0.6% by mass;

910-203*sqrtC + 44.7 Si - 15.2 Ni +31.5 Mo +104 V + 13.1 W - 30 Mn + 11 Cr + 20 Cu -700 P - 400 Al- 120 As - 400 Ti

This equation was developed by K.W. Andrews, and is published in the Journal of Iron and Steel Institute, July 1965

 

[mp87]

For your information, a patient man called Antonio Augusto Gorni takes care of updating regularly a handbook which collects a lot of these empirical formulas (including that reported by metengr in the above post).

You can find it here.

 

[Dalinus]

Thank you.