High-chromium martensitic heat-resistant steel and manufacturing method thereof

Abstract

The invention belongs to the technical field of heat-resistant alloys, and particularly relates to high-chromium martensitic heat-resistant steel with high oxidation resistance and high creep resistance at a high temperature. The high-chromium martensitic heat-resistant steel is a novel structural material mainly applied to the manufacturing of high-pressure steam pipelines for super (ultra super)-critical thermal power stations. The steel comprises the following components in percentage by weight: 0.07 to 0.10 percent of C, 10.0 to 11.0 percent of Cr, 0.3 to 0.5 percent of Mo, 2.0 to 3.0 percent of W, 2.0 to 3.0 percent of Co (the content ratio of Co to W is more than or equal to 0.8 and is less than or equal to 1.2), 0.3 to 0.5 percent of Mn, 0.2 to 0.4 percent of Si, less than 0.5 percent of Ni, 0.001 to 0.006 percent of B, and the balance of Fe. In the high-chromium martensitic heat-resistant steel, by compoundly adding low molybdenum, high tungsten and high cobalt when the chromium content is increased and keeping the content ratio of cobalt to tungsten within a certain range, the coarsening of M23C6 which plays a role in precipitation strengthening in a microstructure can be inhibited, the content of delta-ferrite in the microstructure is effectively controlled to be lower than 5 percent (volume fraction), and the solid solution strengthening effect is greatly improved, so that the high-chromium martensitic heat-resistant steel which has both high oxidation resistance and high creep resistance at a high temperature and is used for thermal power stations is obtained.

Description

technical field [0001] The invention belongs to the technical field of heat-resistant alloys, and specifically relates to a high-chromium martensitic heat-resistant steel with high oxidation resistance and high creep resistance at high temperatures and a manufacturing method thereof, which is mainly used in the manufacture of super ( A new structural material for high-pressure steam pipes used in ultra-supercritical thermal power plants. Background technique [0002] Ultra (ultra-super) critical thermal power technology is an important direction for the development of thermal power in my country in the future, and it is of great significance for the country to achieve the goal of energy conservation and emission reduction. The heat-resistant structural steels used in super (ultra super) critical thermal power plants can be divided into two categories: austenitic steel and martensitic steel. Compared with austenitic stainless steel, martensitic heat-resistant steel has the c...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a high-chromium martensitic heat-resistant steel and its manufacturing method, to solve the problems in the prior art that cannot meet the requirements of higher oxidation resistance and higher creep resistance at the same time

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