Easily welded ageing high-strength steel and heat treatment process thereof

Abstract

The invention discloses easily welded ageing high-strength steel and a heat treatment process thereof. The steel comprises the following chemical compositions in percentage by weight: one ore more of 0.02 to 0.10 percent of C, 0.05 to 0.45 percent of Si, 0.50 to 1.50 percent of Mn, 1.00 to 1.80 percent of CU, 1.00 to 4.00 percent of Ni, 0.10 to 1.00 percent of Cr, 0.10 to 0.80 percent of Mo, 0.01 to 0.06 percent of Nb and 0.01 to 0.05 percent of V, and the balance of Fe and inevitable impurities. The heat sensitivity coefficient of the steel Pcm is less than or equal to 0.35 percent. The heat treatment process comprises the following steps of: directly quenching a steel plate subjected to finished rolling, and cooling the steel plate to the temperature below martensite transition temperature at a speed of 20-50 DEG C / s; reheating the steel plate to the temperature of between 550 and 700 DEG C, and keeping the temperature for 1.2min / mm to 3min / mm; and cooling in air to room temperature. The steel plate has the yield strength of more than or equal to 850N / mm<2>, which is obviously higher than that of the traditional quenched and tempered similar steel, has the V-shaped Charpy impact energy of more than or equal to 150J at -20DEG C, and keeps good toughness.

Description

technical field [0001] The invention relates to an aging high-strength steel and its heat treatment process, belonging to the field of low-alloy steel manufacturing, in particular to a low-carbon copper-containing aging high-strength steel and its direct quenching heat treatment production method, especially suitable for marine engineering structures Construction of welded structures such as ships and drilling platforms. Background technique [0002] With the development of shipbuilding and marine engineering technology, the requirements for the strength level and low temperature toughness of structural steel are getting higher and higher. At the same time, it must have excellent weldability to reduce the difficulty and cost of structure construction. Before the application of the present invention, copper-containing aging low-carbon steels were generally produced by normalizing or quenching and tempering processes, and were mainly used to replace traditional medium-low carb...

AI Technical Summary

Problems solved by technology

The above-mentioned Cu-strengthened high-strength steel produced by traditional normalizing or quenching and tempering process not only has a low strength level, but also needs to reheat the rolled steel plate to a temperature above austenitization for quenching during the production process, which has high energy consumption and long production cycle Shortcomings

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