JPS61110752A - Oxidation resistant iron-nickel-chromium alloy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to improving the oxidation resistance of well-established commercial iron-nickel-chromium alloys.

BACKGROUND OF THE INVENTION Nominal N130~j3%, Cr/l~25%, aluminum o, tr~o,b%, titanium 0.15~0.
4%, copper 0.7! - up to 1% silicon, 0. /
Iron-nickel-chromium alloys containing residual iron impurities have long been used in applications such as heat exchanger tubing, process piping, carbonization fittings and retorts, furnace components, thermoelectric sheathing, etc. .

It is known for its resistance to oxidation at high temperatures and for a number of other properties such as stable structure, ductility, resistance to carburization, resistance to corrosion, etc.

SUMMARY OF THE INVENTION Despite the characteristics of the commercial alloys described above, it has been discovered that oxidation resistance at high temperatures can be improved by controlling the amount of manganese present in the composition.

DETAILED DESCRIPTION OF THE INVENTION In general, the present invention contemplates improving the oxidation resistance of manganese-containing iron-nickel-chromium alloys by controlling the amount of manganese such that it does not exceed about 0.6%. Manganese, as is well known, confers a number of advantages due to its presence in such materials, such as the ability to fix sulfur, which would otherwise have an adverse effect on various metallurgical properties.

Manganese is also believed to enhance weldability and is believed to act as a deoxidizer. Its use is based on carryover from steelmaking practices.
r). In any case, the primary objective of the present invention is not to exclude manganese as an essential component from iron-nickel-chromium alloys of the type being considered, but rather the objective is to control manganese and to demonstrate herein. The aim is to obtain the benefit of improved oxidation resistance such as

The compositions of commercial alloys and representative alloys of the present invention are provided in Table I below.

Table I Commercial alloys oybo, oa, 7/·132'-,70,!
t20・“70・“0,368m1・/0.
10 0. IM 3, 93 m, des o, l
Igo, to θ, OII O,! r'l B
ml.

Ba1. - Remaining 10 Impurities Table ① is a report on oxidation behavior after the test. In this regard, an air-melted sample tq kg was forged into a flat bar, hot rolled to 0.1/coin (approximately O0 = crIL), and then cold rolled to 0.123 in. (approximately 0.3/li!rcIL). A cyclic oxidation test is utilized, and this involves exposing the specimen to a temperature of 1800 °C.
It consisted of a hold for S minutes followed by cooling in air for 5 minutes. This cycle was repeated over a test period of / 000 hours. io test piece.

Checked after increment of time. Before the test, the test piece is coated.

Annealed at 7'F and water quenched.

The oxide was removed by grinding to /20 grit.

As can be seen from Table 1, alloy 1 of the present invention performed significantly better than the commercial alloy. The differences were mostly in manganese content/% vs. O,/%, respectively.

A similar pattern can be seen from Tables ■ and ■ during cyclic oxidation testing at 1000'F.

It is believed that the present invention is applicable to iron-nickel-chromium alloys that experience or will experience a loss of oxidation resistance due to the excess component manganese. In this connection, the invention particularly provides nickel with ~3% and chromium/~3%.
25%, manganese in amounts up to about o, bcs, carbon 0,3
%, aluminum/%, titanium/%, copper/%, the remainder pertains to alloys containing essentially iron. If present, silicon need not exceed 5%.

Sulfur and phosphorus should be kept at low levels consistent with good melting practices. Nitrogen can be present up to about 0.3%, for example o, or to 0.8%. At least one of aluminum and titanium, advantageously both, o
, oh~O1ri! Preferably, it is present in an amount of

Although the invention has been described with preferred embodiments, it is to be understood that modifications and variations may be made thereto without departing from the spirit and scope of the invention, as would be readily apparent to those skilled in the art. It's rubegi. Such modifications and variations are considered to be within the power and scope of the invention.

-2 Introduction

Claims (1)

[Claims] 1. 1800-2000°F (approximately 982-1093°C)
A nickel-chromium-iron alloy characterized by good oxidation resistance at elevated temperatures of about 20% to about 45% nickel and about 15% to about 2% chromium.
5%, manganese up to about 0.6%, aluminum and titanium up to about 1% each, steel up to about 2%, carbon about 0.3%
Nickel-chromium-iron alloy, characterized in that it consists of up to 0.3% nitrogen, the balance essentially iron. 2. At least one of aluminum and titanium is 0
．． The alloy according to claim 1, present in an amount of 0.05 to 0.75%. 3. Nickel is 30-35% and chromium is 19-2
3% and up to 0.2% carbon. 4. The alloy of claim 1, wherein the silicon does not exceed about 1.5%. 5. A nickel-chromium-iron alloy, characterized in that its oxidation resistance is improved by controlling manganese so that it does not exceed 0.6%.