J55 and N80 are a common part of the oil casing material. However, these two materials are some differences.

The difference between the J55 and N80
1. Yield strength of the N80 is higher than the J55 up to 173 ~ 206 MPa.
2. On the same area of ​​the sample, the elongation of N80 is higher than J55.
3. Under the same size, the same sample orientation, the same minimum sample size, J55 grade couplings, coupling stock, coupling material, semi-finished and coupling attachment material can absorb lower than N80 steel grade.
4. The nondestructive testing methods of seamless pipe,coupling stock, welded tube with J55 and N80 is differeent.
5. J55 and N80 steel grade is not the same color: length greater than or equal 1.8m, J55 painted a bright green, N80 painted a red;
6. J55 chosen by the manufacturer, or organize according to the order specified length normalized (N), normalizing and tempering (N & T) or quenching and tempering (Q & T). N80 is a whole, full-length heat treatment is mandatory. By the manufacturer selected for normalizing (N) or normalizing and tempering (N & T) + quenching (Q).