micro structure of cf 53a material

[marcmtar]

Dear Sir
we are hereby providing the detail of Metals we Purchase regularly for our Ball Screw Production:
Material: Cf-53A
Micro Structure: Spheroidised,Pearlite and Ferrite, Free from Hamful and Continues Bonding
Hardness: 225 - 275 BHN

But the Supplier insisting us to accept the material availble with him with following specification:
Micro Structure: Ferrite + Slight Spherodised Carbide+Lamellar Pearlite
with BHN 180 .

Supplier provided small metal sample for Microstructure examination at our end.

We request you suggest us whether we can use the material suggested by the supplier for our ball screw manufacturing or not?
We also request you to provide your comments on this subject.

Regards
G.Vinod Kumar
MARC Manufacturers Pvt Ltd,
Hyd, India
Email:marc@marcballscrw.com

 

[TVP]

If I understand the designation correctly, then CF-53 is a German grade of plain carbon steel with C = 0.50-0.57. If this is correct, then your specification does not really make sense, in that the hardness is too high for a spheroidized microstructure. A 0.50 carbon steel in the spheroidized condition would have a typical hardness range of 156-217 HB. Your specification of 225-275 seems more consistent with a product that has been annealed and then cold drawn. Typically, if the application requires a more homogeneous structure, better straightness, etc., cold drawing using small reductions (~ 10-15%) is specified.

So, your suppliers recommendation of a lamellar pearlite anneal with some spheroidization and a hardness of 180 HB is more consistent with the microstructure requirement of your specification. Perhaps you should obtain more details from your current supplier on how the steel is processed before proceeding further.