# US 4,398,951 A · Fermalloy(Fe-Mn-Al stainless steel)

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,398,951 A
- Document ID: US4398951A
- Status: Granted
- Kind: A
- Application number: 06/367,800
- Filed: 1982-04-12
- Granted: 1983-08-16
- Earliest claimed: 1981-04-22
- Assignees: Unisearch Limited
- Inventors: Greig R. Wallwork
- Web page: https://patentgrep.com/patent/US4398951A

## CPC

- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

The invention provides corrosion-oxidation resistant alloys based on iron, using aluminum (usually about 4 to about 9% by weight) as the element which prevents corrosion/oxidation, and manganese (usually about 3 to about 15% by weight) and containing from 0 to about 6% chromium. The alloys are referred to collectively as "Fermalloys". The invention provides alloys with high ductility at working temperatures and reasonable malleability at room temperature. Some scale deterioration that may occur on these rather simple alloys can be eliminated using minor additions of rare earth elements and some degree of high temperature strengthening may also be possible by the addition of carbon to form carbides.

## Claims

### Claim 1

A substantially ferritic alloy consisting essentially of
aluminium--4 to 9%,
manganese--3 to 15%,
chromium--0 to 6%, and
iron--balance to 100%.

### Claim 2 (depends on 1)

The alloy of claim 1 wherein the chromium is present.

### Claim 3 (depends on 1)

The alloy of claim 1 consisting essentially of
aluminium--about 5%,
manganese--<15%,
chromium-->5%, and
iron--balance to 100%.

### Claim 4 (depends on 1)

The alloy of claim 1 consisting essentially of
aluminium--about 5%,
manganese--about 5%,
chromium--about 5%, and
iron--balance to 100%.

### Claim 5 (depends on 1)

The alloy of claim 1 consisting essentially of
aluminium--about 5%,
manganese--about 7.5%,
chromium--about 5%, and
iron--balance to 100%.

### Claim 6

A substantially ferritic alloy consisting essentially of
aluminium--6 to 10%,
manganese--5 to 10%, and
iron--balance to 100%.

### Claim 7 (depends on 1, 2, 3, 4, 5, 6)

The alloy of any one of claims 1 through 6 wherein there is also present at least one of the group consisting of carbon and at least one rare earth element.

### Claim 8 (depends on 1, 2, 3, 4, 5, 6)

A corrosion and oxidation resistant article consisting essentially of the alloy of any one of claims 1 through 6.

### Claim 9 (depends on 1, 2)

A corrosion and oxidation resistant article consisting essentially of the alloy of claim 1 or 2 wherein there is also present at least one of the group consisting of carbon and at least one rare earth element.