Heat treating CA6NM
Heat treating CA6NM
(OP)
Can anyone throw some tips on cycle to be followed while heat treating ASTM A 352 CA6NM as per NACE MR 0175 ( 255BHN max?
Thanks
Thanks
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: Heat treating CA6NM
From what I found even 262HBN (23HRC) is very difficult to attain. C should be below 0.03% and NACE specifies the following heat treatment:
austenitise at 1010°C min, air cool or oil quench at room temperature
temper at 675°C, air cool to room temp.
temper at 600°C, air cool
This treatment does not guarantee attaining a hardness of less then 23HRC (or 262HBN) for C<0.03%!
All this is based on old data (1990’s). Possibly things have changed in the mean time.
RE: Heat treating CA6NM
The material specified for your casting is a
corrosion resistant martensitic type with about
0.6%C 13%Cr 4%Ni and 0.4%Mo
General recommendations for heat treatment of this
type of stainless include:
1) - Homogenization above 2000 F (1090 C) to promote
uniformity of chemical composition and of microstructure:
this process is used to diminish the presence of alloy
segregation and of dendritic structure, especially in heavy
sections.
2) - Austenitizing at 1800 to 1850 F (980 to 1010 C)
and air cooling for hardening.
3) - Tempering to take place immediately, before parts reach
room temperature, to suit hardness requirement,
possibly 1150 F (620 C).
Tempering range from 700 to 1100 F (370 to 590 C) is to be
avoided because it produces low impact values.
Double tempering is recommended.
Hope this helps.
E. Levi
http://www.welding-advisers.com/
RE: Heat treating CA6NM
Depending on your customer you might want to ask whether they want NACE hardness or NACE cylce?
RE: Heat treating CA6NM
Maintaining a low carbon in the range 0.03 helps.
RE: Heat treating CA6NM
Austenatize at 1900F and Air cool to Room temperature. Double temper is recommended; 1250F , air cool to 60F min (important) and 1150F, air cool to room temperature. Longer holding times at both temperatures yeild lower hardness values.
The % carbon coupled with the above heat treatment will typically develop a hardness in the range of 228 - 248 BHN @ 3000kgf - 15 sec. Measure the hardness in BHN.Conversion from BHN to Rc is not recommended since there is very little known about the relation netween BHN to Rc with respect to CA6NM. Per NACE, the maximum hardness desired for sour environments is 255BHN. The above heat treatment follows NACE, ASTM A487 and A352.
Thanks, Mahadhatu