NACE MRO175

[remetaper]

During these last years, I found that there is a lot of different opinions about the use of "improved or enhanced machinabilty of austentic stainless steels according to Nace MRO175-2009. I'm talking to standard Astm 304/304L and 316/316L and NOT to free machining stainless steel as Astm 303.In particularly, I'm reffering to those austenitic grade Calcium - Sulphur Treated according to a steel making procedure where a special morphology of inclusions are obtained in order to reduce the tool crater wear and improves machinability. Obviously, the content of S& and P% are less than < 0,03% ( Nace said <0,045%). The main brands in Europe and USA are UGIMA,PRODEC,MAXIVAL,SANMAC, PROJECT 70 (7000) and so on. These popular grades (304-316) could give some problem during welding in terms of floating, slagging of weld pool together a irregular geometry of weld pool ( surface tension). This could be the main reason why these kind of Ca-treated grades could cause difficulties. The rest of products ,obtained by machining,forging,extrusion,cold drawing and so on are not involved in this trouble.
Therefore, because C,Cr,Ni, Mn,Si and mainly S&P% are according to Nace, there is no reason why these Ca-treated grades couldn't be according to above Nace.
Thank you in advance for you opinions.