Influence of Microstructure on DWTT Performance of Thin-wall X65M Pipeline Steel
The paper addresses the issue of fluctuating low-temperature drop-weight tear test(DWTT)performance in 6-8 mm thin-wall pipeline steel,the influencing factors of the control process of low-temperature DWTT of X65 thin-wall pipeline steel have been explored.With microstructure analysis and numerical deconstruction study of different low-temperature DWTT results,,it reveal that the size of polygonal ferrite grains and the distribution of M/A constituents in the central part of the steel plate significantly affect low-temperature DWTT performance.When the average area of grains with an area ≥200 μm2 is greater than 260 μm2,and the proportion of M/A constituents is greater than 6％,DWTT perfor-mance shall deteriorate significantly.By optimizing the composition and continuous casting and rolling processes,control of grain size and M/A constituents can effectively improve the low-temperature DWTT performance of thin-specification pipeline steel.The related product has achieved stable production of more than 80,000 tons,meeting the requirement of -30 ℃ low-temperature DWTT,it is of great significance for the development and production of thin-wall pipeline steel products.
Thin-wall Pipe Line SteelDWTTGrain SizeM/A MicrostructureX65M
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