OK 48 is E 7018 and is with Mn up to 1.2%
The impact strength is 80 J at -40 C. UTS values are app. 540 N/sq.mm. Works win DCEP,
DCEN & AC 90 OCV.
OK 55 is E 7018-1 and is with Mn up to 1.5%
The impact strength is 80 J at -50 C. UTS values are app. 590 N/sq.mm. Works with only DCEP & AC 65 OCV t
U will get the values after a prolonged PWHT.
As U have seen, impact strength is higher in OK 55 and recommended
where more impact is needed.
The baking temp. weld ability is same except that, u will end up paying
bit more for OK 55.There is no necessity to change to OK 55 when not needed.
Regards,
C Sridhar.
Technical Adviser - Welding,
for Alsta Pristine Engineering Private Limited, --(SS fab). Bangalore
(A venture of Advance Eng. Training & Inspection Services). Chennai,
Mobile nos: 0 94449 71097, 0 7406 326326, 0 94445 21267.