Metal material having excellent metal dusting resistance

Abstract

[Objective] To provide a metal material having excellent metal dusting resistance which is suited for using cracking furnaces, reforming furnaces, heating furnaces or heat exchangers, in petroleum refining, petrochemical plants, etc.

[Means for Solution] A metal material having excellent metal dusting resistance, characterized in comprising, by mass %, C: 0.01 to 0.4%, Si: 0.01 to 2.5%, Mn: 0.01 to 2.5%, Cr: 15 to 35%, Ni: 20 to 65%, Cu: 0.05 to 20%, S: not more than 0.1%, N: not more than 0.25% and O (oxygen): not more than 0.02% and the balance Fe and impurities, and also containing, by mass %, one or more selected among the elements of P: more than 0.05% and not more than 0.3%, Sb: 0.001 to 1% and Bi: 0.001 to 0.5. It may further contain one or more selected among the elements of Nd: 0.001 to 0.15%, Co: not more than 10%, Mo: not more than 3%, W: not more than 6%, Ti: not more than 1%, Nb: not more than 2%, B: not more than 0.1%, Zr: not more than 1.2%, Hf: not more than 0.5%, Mg: not more than 0.1%, Ca: not more than 0.1%, Al: not more than 0.8%, Y: not more than 0.15%, La: not more than 0.15% and Ce: not more than 0.15%.

Description

TECHNICAL FIELD[0001]The present invention relates to a metal material which is high in strength at elevated temperatures, excellent in corrosion resistance and is to be used in particular in a carburizing gas atmosphere which contains hydrocarbon gases, CO gas, and in particular in a metal material having excellent metal dusting resistance, which is suited for use to cracking furnaces, reforming furnaces, heating furnaces or heat exchangers in petroleum refining or petrochemical plants.BACKGROUND ART[0002]The demands for such clean energy fuels as hydrogen, methanol, GTL (gas to liquids) and DME (dimethyl ether) are expected to grow markedly in the future. Therefore, the refining apparatus for producing such synthesis gases will become larger-sized and will be required to be much higher in thermal efficiency and suited for mass production. Also, the conventional refining apparatus in petroleum refining and petrochemical plants, the conventional ammonia production apparatus or hydro...

AI Technical Summary

Benefits of technology

[0043]The metal material according to the present invention has an effect of suppressing the surface reactions between carburizing gases and the metal and is excellent in metal dusting resistance and therefore can be used for constructing cracking furnaces, reforming furnaces, heating furnaces, heat exchangers in petroleum refining or petrochemical plants and can markedly improve the durability of apparatus and the operation efficiency.

[0044]The reasons for restricting the content ranges for the respective elements in the metal material in accordance with the present invention are as follows. In the description that follows, the designation “%” for the content of each element means “mass %”.

[0046]A C content of 0.01% is necessary for securing the strength at elevated temperatures. However, at levels exceeding 0.4%, the toughness of the metal markedly deteriorates, so that the upper limit is set at 0.4%. A preferred range is 0.03 to 0.35%, and a more preferred range is 0.03 to 0.3%.

[0048]Si has strong affinity for oxygen and encourages uniform formation of protective layers of oxide scales such as Cr2O3. Further, it forms Si-based oxide scales under the Cr2O3 layer, wh

Problems solved by technology

However, the heat exchange in the lower temperature range might cause problematic corrosion due to the carburization phenomenon in a Fe alloy containing a high Cr and high Ni, which is used for reactor tubes and heat exchangers.

However, the surface of those parts in a relatively low temperature within heat exchanger causes carburization due to the penetration of C from the metal surface, because the forming of the oxidized dense layers effective in suppressing corrosion are delayed due to the insufficient diffusion of Cr and Si to the metal surface from the inside, and also because the gases containing hydrocarbons are converted to carburizing ones.

As a result, fine cracks tend to appear and, in the worst case, the metal pipe in use will burst.

Further, when the metal surface is exposed, a coking, deposition of carbon on the metal surface, is caused by the metal functioning as a catalyst, which is accompanied by decreases in the passage area in the pipe and this decreases the heat transfe