DE662432C - Items made of chrome steels, which must be resistant to attack at high temperatures - Google Patents

Description

Items made of chrome steels that can withstand high temperatures must be resistant to attack. Alloys are already known, those against corrosion at high temperatures, especially against corrosion by oxygen, Carbonic acid, sulphurous acid, water vapor and mixtures of these gases, resistant are. It is also known that these alloys contain silicon, cobalt, tungsten, Molybdenum, aluminum, vanadium and the like.

The invention is based on the object; To improve the resistance of objects made from such alloys to corrosion at high temperatures and, in particular, to attack at high temperatures by oxygen, gases containing carbon dioxide, gases containing sulfur, water vapor or blast furnace gases. According to the invention, this is achieved by using iron alloys with 10 to 40 % chromium, 30 to 60% nickel, 0.5 to 5% zirconium, the remainder iron or iron alloys with 10 to 40 ° / o chromium, 1 to 6 % aluminum, 0.5 to 6 % silicon, 0.5 to 5% zirconium, the remainder iron can be used. The first-mentioned iron alloys are against attack at high temperatures by gases containing carbon dioxide, gases containing sulfur; Water vapor and blast furnace gases resistant while the on. The alloys mentioned in the second place must be resistant to attack by oxygen, gases containing carbon dioxide, gases containing sulfur, water vapor or blast furnace gases at high temperatures.

Iron is to be understood as meaning one with the usual contents of Mn, P, S and optionally Si. The following iron alloys are used as preferred embodiments for the stated purpose according to the invention: a) Iron alloys with 10 to 40%, chromium, 3o to 60% nickel, 0.5 to 5% zirconium, also with up to 40% carbon, up to 60 % silicon, tungsten, titanium, vanadium, cobalt or copper, individually or in groups, the remainder being iron; b) iron alloys with 10 to 40 0/0 chromium, 1 to 6 % aluminum, 0.5 to 6 0% silicon, o; 5 to 5 % zirconium, further with up to 4'1, carbon, up to 6,% tungsten, Titanium, vanadium, cobalt or copper, individually or in groups, with the proviso that the sum of the contents of silicon and the above-mentioned additional metals does not exceed 6%, the remainder being iron; c) iron alloys with 10 to 40% chromium, 30 to 60% nickel, 0.5 to 5 zirconium, o; 5 to 6% silicon, remainder iron; d) iron alloys with 10 to 40% chromium, 0.5 to 6% silicon, 0.5 to 50 / a zircon, 0 to 40% carbon, 0.5 to 1 0/0 aluminum, remainder iron; e) iron alloys with 10 to 40% chromium, 0.5 to 5% zirconium, 0 to 4% carbon; 1 to 5% aluminum, 1 to 6% cobalt, the remainder iron.

It is known that stainless steels, which neither by vegetable acid nor to be attacked by the influence of the outside air, using of a zirconium additive of up to i%: It is also known for electrical Resistance wires or also for stainless or corrosion-resistant steels as cleaning or Refining agent or zirconium additives to improve the mechanical properties apply up to 2%. In contrast, the invention concerns use of alloys with added zirconium to solve other tasks, based on the new knowledge that just the addition of zirconia at high temperatures and at a simultaneous attack by gases of the specified type an essential Improvement of the properties of the surface layer created by the initial corrosion achieved and at the same time the onset of this corrosion is delayed.

Comparative tests have been carried out with three iron alloys, which are referred to below as A, B and C, respectively; The alloys contained the following components in addition to iron: Alloy A: 30% chromium, 0.6% silicon. Alloy B: 25% chromium, 0.5% silicon, 2.5% aluminum.

I alloy C (according to the invention) 25% chromium, 0.5% silicon, 2.2% aluminum; 1.5 0% zircon. The following results were obtained.

The weight increase in mg / cm2 / hour for each of the three alloys was: Furthermore, an iron alloy containing 30% chromium and 49% nickel resulted in a weight increase of 1.2 mg / cm2 / hour after 11/2 hours. at 10,000 ° in a sulfur-containing gas, while after the same time an iron alloy containing 32% chromium, 47% nickel, 2% silicon and 0.75% zirconium gave only a weight increase of 0.6 nig / cm / hour.

Claims (7)

PATENT CLAIMS: i. The use of ferrous alloys, consisting of from 10 to 40% chromium, 30 - 60% nickel, 0.5 - 5% zircon, the remainder iron; as a material for objects that are resistant to attack at high temperatures carbonated gases; Sulphurous gases, water vapor and blast furnace gases resistant must be. 2. The use of iron alloys; consisting of io to 40% chrome, i - 6% aluminum, 0.5 - 6 0% silicon, 0.5 - 5% zirconium, the remainder iron, as the material for items that are against corrosion at high temperatures, especially against a high temperature attack by oxygen, carbonated Gases, sulphurous gases, water vapor or blast furnace gases, be resistant have to. 3. The use of iron alloys, consisting of the in claim i mentioned Contained in chromium, nickel and zirconium, furthermore with up to q. ° / o carbon, - 6 ° / o Silicon, tungsten, titanium, vanadium, cobalt or copper, individually or in groups Remainder iron, for the purpose according to claim r. q .. The use of iron alloys, consisting of the chromium, aluminum, silicon contents mentioned in claim 2 and zircon, furthermore with up to 4 '/, carbon, - 6% tungsten, titanium, vanadium, cobalt bare copper, singly or in groups; with the proviso that the sum of the contents of silicon and of the above additional metals does not exceed 6%, the remainder Iron, for the purpose according to claim 2. 5. The use of iron alloys, consisting of the chromium, nickel and zirconium contents mentioned in claim i, further with 0.5 to 6% silicon, remainder iron, for the purpose according to claim r. 6. The Use of iron alloys, consisting of the contents mentioned in claim 2 on chromium, silicon and zirconium and also with o to q. ° / "carbon, 0.5 - z% Aluminum, the remainder being iron, for the purpose according to claim 2. 7. The use of iron alloys, consisting of the chromium and zirconium contents mentioned in claim 2, furthermore with 0 to 4 % carbon, i - 5% aluminum, i - 6 ° / a cobalt, remainder iron, for the purpose according to claim 2.