Thick-specification high-tenacity X70 acicular ferrite pipe line steel and manufacturing method thereof

Abstract

The invention discloses thick-specification high-tenacity X70 acicular ferrite pipe line steel and a manufacturing method thereof. The thick-specification high-tenacity X70 acicular ferrite pipe linesteel comprises components as follows in percentage by weight: C: 0.03%-0.06%. Si: 0.15%-0.25%, Mn: 1.55%-1.75%, P: 0.012%-0.020%, S: less than or equal to 0.003%, Cu: 0.20%-m0.35%, Nb: 0.06%-0.08%, Ti: 0.01%-0.02%, AIs: less than or equal to 0.05%, and Mo: 0.20%-0.30%. The manufacturing process of the thick-specification high-tenacity X70 acicular ferrite pipe line steel is characterized in thatcontinuous casting speed is 1.2-1.8m / min; casting temperature of plate blanks is above 550 DEG C; the temperature is raised to 1100-1250 DEG C and kept for 80-120min; the roughing delivery temperatureis 920-1080 DEG C; the finish rolling delivery temperature is 760-880 DEG C; the cooling speed is 10-30 DEG C / s; and the coiling temperature is 450-570 DEG C. The thick-specification high-tenacity X70 acicular ferrite pipe line steel meets and is superior to the performance requirement of API 5LX70 acicular ferrite pipe line steel; meanwhile, the thick-specification high-tenacity X70 acicular ferrite pipe line steel has excellent HIC resistance and is suitable to tick-specification large-caliber high-pressure gas transmission pipelines which requires to be continuously enlarged.

Description

technical field [0001] The invention belongs to the technical field of metallurgical metal pressure processing, and relates to a method for producing a thick-gauge, high-toughness X70 acicular ferritic pipeline steel using a medium-thin slab continuous casting and rolling production line. Background technique [0002] Since the 1990s, China's economy has developed rapidly, and the average growth rate of the national economy has exceeded 7%. On the one hand, the rapid economic development has promoted the development of China's petroleum industry, and on the other hand, it has also brought enormous pressure to the development and utilization of China's oil and gas resources. Especially since the 21st century, the development and utilization of domestic oil and gas resources has been increasingly unable to meet the needs of economic development, and the dependence on imported crude oil has become higher and higher. Pipeline transportation is the most economical and reasonable...

AI Technical Summary

Problems solved by technology

Due to the technical characteristics of the medium and thin slab continuous casting and rolling production line (coarse austenite grains before rolling and slightly smaller total reduction ratio), the pipeline steel produced by the ordinary process on this production line cannot meet the requirements of the project The mechanical performance standard

At present, the design and manufacture of X70 acicular ferritic pipeline steel hot-rolled coils are rolled by conventional units, that is, the production is carried out by the process of cold-loading after the slab is off-line. There are no patents for the production of high-grade pipelines, especially thick-gauge, high-toughness X70 acicular ferritic pipeline steel.

Images