CF3, CF3A, CF3M Materials
CF3, CF3A, and CF3M are austenitic stainless-steel casting as per ASTM A 351 material specification.
CF3, CF3A and CF3M are three materials that have been developed to increase the strength and durability of stainless steel.
These three materials contain high levels of chromium, nickel and molybdenum, which make them resistant to corrosion and oxidation in a variety of environments.
The highest-grade variant known as CF3M contains similar elements but features an even higher level of resistance against corrosive environments due to its high molybdenum content (similar to AISI 316 stainless steel).
CF3, CF3A, CF3M Material Specification
The material specification for CF3, CF3A, CF3M is ASTM A351 specification. The UNS Number of these grades are:
- CF3: J92500
- CF3A: J92500
- CF3M: J92800
ASME Section IX P Number for CF3, CF3A, CF3M is P8, and Group Number is 1. CF3 and CF3A are similar to AISI 304 stainless steel while CF3M is equivalent to AISI 316 stainless steel.
CF3, CF3A and CF3M chemical composition
The chemical compositions of CF3 and CF3A are given in the below table.
| Element | CF3 and CF3A |
| C% | 0.03 max. |
| Cr% | 17 – 21 |
| Mn% | 1.5 max. |
| Mo% | 0.5 max. |
| Ni% | 8 – 12 |
| Si% | 2 max. |
| P% | 0.04 max. |
| S% | 0.04 max. |
The chemical compositions of CF3M are given in the below table.
| C% | Mn% | Si% | Cr% | Ni% | P% | S% |
| 0.03 | 1.00 | 1.50 | 17- 21 | 9- 13 | 0.04 | 0.03 |
Welding CF3 and CF3A Casting
When welding these metals, it is important to use the right filler materials in order to achieve a successful weldment.
Stick welding using an E308L-15 rod (AWS A5.4 specification) is recommended for most applications involving CF3 and CF3A metals.
TIG (tungsten inert gas) welding should utilize an ER308L filler material while MIG (metal inert gas) welding uses an ER308L filler wire as well.
TIG welding shall be used with pure argon gas shielding. For MIG welding, a mixture of argon + O2 should be used.
Read more about Welding Shielding Gas Selection for Stainless Steel welding.
Welding preheating is not required for CF3, CF3A and CF3M casting materials welding. It is recommended to use stringer weld beads with low welding heat input for maintaining corrosion resistance of weld metal.
Welding CF3M Casting
The weld procedure for CF3M castings must be carefully chosen in order to ensure successful joining without any structural integrity issues arising.
Pre-weld cleaning is essential before beginning the welding process because contaminants can lead to weak welds or corrosion problems.
Stick welding of CF3M casting is carried out using E316L-15 welding rod. Cf3M contains added molybdenum and have same metallurgy as AISI 316 stainless steel.
Welding using E308L shall not be used for CF3M casting as E308L does not contains molybdenum which is important for pitting corrosion resistance.
TIG and MIG Welding of CF3M is carried out using ER316L or ER316LSi filler wire rods (as per AWS A5.9 specification).
Pure argon shall be used for weld shielding and purging to protect the weld from the oxidation and contamination.
