What is the basic difference between 312-16 and 308L stainless steel welding rod?
Assuming we are talking about stick welding (SMAW):The first three digits refer to the alloy type
312 vs 308.
The presence of two digits after the hyphen in 312-16 have specific meaning.
The first digit is either a 1 or a 2. A one means that the electrodes 5/32 or smaller are useable in all positions and larger are useable in only in flat and horizontal positions; a 2 indicates that all sizes are useable only in the flat and horizontal positions
The second digit is either a 5, 6 or 7. A 5 means the electrodes are suitable for use with DCEP (Direct Current Electrode Positive); a 6 or 7 refers to electrodes suitable for either AC or DECP.
So -16 means (for 5/32 and smaller) all postions and AC/DECP
The letter L in 308L refers to the control of carbon concentration to a specified lower level... while still complying with the chemistry of 308 stainless.Were there an H instead,it would mean that the electrode has a higher carbon level, possibly not consistent with the chemistry of the parent 308 class.
Some vendor information (taken randomly from one of many vendors) has information as to applications and parent metal chemistry:
http://www.jwharris.com/images/pdf/312-16.pdf
http://www.jwharris.com/images/pdf/308l-16.pdf
I hope this addresses your question.
owhn