A kind of eh36 extra-thick plate for high heat input welding with normalized delivery and its preparation method

Abstract

Provided is an as-normalized EH36 extra-thick steel plate useful for high heat input welding. The steel plate comprises the following components in mass percent: 0.08%-0.05% of Als, greater than or equal to 0.025% of Nb, 80-100 ppm of N, and 0.06-0.10% of V. The content of V, Ti and N in the steel plate satisfies that V / N is greater than or equal to 6.0 and TI / N is greater than or equal to 1.5. The present invention also provides a preparation method of the steel plate at the same time. The normalized extra-thick plate produced according to the present invention can meet the requirements of performance indicators of 80-100 mm EH36 simultaneously, and can also meet the requirements of high heat input welding. According to the present invention, the steel plate is simple in preparation process and excellent in overall mechanical performance, and can be widely applied to the fields of shipbuilding, ocean engineering equipment manufacturing, offshore wind power and the like.

Description

technical field [0001] The invention relates to the field of extra-thick steel plates, in particular to an EH36 steel plate for large heat input welding and a preparation method thereof delivered in a normalized state. Background technique [0002] Compared with the land environment, ships, marine engineering equipment and offshore wind power generation equipment often face complex service environments such as high temperature, high humidity, high salinity, extreme cold, ice floes abrasion and impact, surge, etc. In addition, they may also suffer from typhoons, ice, Earthquakes and other catastrophic environmental forces require steels for marine engineering to have good comprehensive mechanical properties and service performance. Therefore, ship and ocean engineering equipment design units usually choose normalized steel plates with large thickness specifications. And in order to ensure the construction cycle of ships and equipment, the construction unit put forward an urg...

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Problems solved by technology

For example, the patent of Jiangyin Xingcheng Special Steel "A 180-200mm thick EH36 steel plate and its manufacturing method for delivery in normalized state" has the characteristics of 0.11%-0.18% C, 0.01%-0.05% Nb, 0.03%-0.08% V, using 0.05%-0.07% Al instead of Ti element, but it can not meet the requirements of large input energy welding, this is because AlN, Nb (C, N) and other particles in the large input energy welding process Dissolution occurs in the medium and cannot play the role of pinning austenite grain growth

As another example, the patent "Normalizing Steel Plate for Welding High Heat Input Ocean Engineering and Its Manufacturing Method" applied by Nanjing Iron and Steel Co., Ltd. has a carbon content of 0.12-0.18% and a carbon equivalent of 0.42-0.45%, which cannot meet the standard EN10225 Requirements for Carbon Equivalent

In addition, Nanjing Iron and Steel adopts the method of oxide metallurgy to make the welding heat-affected zone contain a large amount of Ti oxides and Ti nitrides. The disadvantage of this patent is that when Ti oxides and nitrides precipitate in the liquid state The growth of oxide particles is not restricted, and the large particle inclusions formed not only fail to inhibit the grain growth of the welding heat-affected zone, but will reduce the toughness of the base metal and heat-affected zone

Therefore, this method is difficult to control in industrial production

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