Submerged arc welding wire for low temperature pipeline K65 hot bending elbows

Abstract

The invention discloses a submerged arc welding wire for low temperature pipeline K65 hot bending elbows. The chemical ingredients of the welding wire include, by weight: 0.01 to 0.05% of C, no more than 0.1% of Si, 1.5 to 2.0% of Mn, no more than 0.01% of S, no more than 0.01% of P, 1.0 to 3.0% of Ni, 0.15 to 0.35% of Mo, 0.01 to 0.05% of Ti, no more than 0.005% of B, no more than 0.005% of Zr, and the balance of Fe and unavoidable impurity. The welding wire matches with sintered flux with the alkalinity ranging from 1.9 to 2.3. Two-sided multi-wire submerged arc welding is performed on a hot bending elbow of pipeline steel K65, the welding wire energy ranges from 50 to 120 kJ / cm, induction heat is performed on the welded pipe by the temperature of 1020 to 1200 DEG C, the pipe is bent in the hot state, water quenching is performed, the temperature ranging from 500 to 750 DEG C is maintained for 1.5 to 2 hours, the welding seam can match with the optimal roughness, the welding seam tensile strength ranges from 660 to 780 MPa, the welding seam impact value Skv > / = 80J by the temperature of minus 40 DEG C, and the various requirements of K65 elbow welding seam in alpine region are met.

Description

technical field [0001] The invention relates to a welding wire for pipe bending, in particular to a submerged arc welding wire for K65 hot-simmered pipe bending of a low-temperature pipeline. Background technique [0002] As the world's energy demand continues to increase, the exploration and development of oil and gas resources is developing in remote areas, and the construction of pipelines in alpine areas has become a hot spot. In order to ensure the safe use of pipelines in polar or alpine regions, the new generation of Russian oil and gas pipeline projects represented by Bovanenkove-Ukhta pipelines uses K65 steel pipes with a strength level equivalent to X80. The low temperature toughness of K65 steel pipes is higher than that of X80 design standards (API SPEC 5L) Higher, the CVN test temperature is -40°C, the average value of the impact energy of the weld is not less than 60J, the single value is not less than 50J, and the weld strength is not less than 640MPa. [000...

AI Technical Summary

Problems solved by technology

However, the welding wire for hot-simmering pipes announced by the former is suitable for X90 / 100 steel grades. Its ultra-high weld strength exceeds the strength requirements of K65, and its toughness test temperature is only -30°C, which cannot meet the -40°C of K65. Requirements for low temperature toughness; the latter announced the welding process of using H08Mn series welding wire and SANi3 welding wire to form a mixed four-wire welding K65 hot-simmer bend pipe parent pipe, but this may cause uneven weld composition and performance fluctuations. In its preferred embodiment The impact absorption energy of the weld at -40°C is only 60~64J, which is insufficient compared with the K65 design standard.