The Effect of Microstructure on Stress-Strain Behaviour and Susceptibility to Cracking of Pipeline Steels

Table 2

Effect of heat treatment on pearlite bands in the “LT” face of grade X65 steel.

Temperature (°C)	Soak time	Mode of cooling	Microstructure	Grain size (μm)	No. of treatments
950	60 h	FC	Banded with average spacing* (AS) 201 μm	24	1
1175	1 h	FC	Slight traces of banding with large pearlite areas and some Widmanstätten	29	1
1175 then 1000	1 h then 20 min	FC	Banded with AS 60 μm	12	2
1175	5 h	FC	Not banded with ferrite/pearlite and some Widmanstätten	50	1
1175 then 950	5 h then 20 min	FC then AC	Not banded (ferrite/pearlite)	9	2
1175 then 950 then 1000	5 h then 20 min then 20 min	FC then AC then FC	Banded with AS 130 μm	10	3
1200 then 1000	20 min then 20 min	FC	Banded with AS 52 μm	13	2

*As-received average pearlite band spacing and average grain size: 19 and 6 μm, respectively.