# US 5,707,586 A · Free machining stainless steel and components for automotive fuel and exhaust systems made therefrom

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- Number: US 5,707,586 A
- Document ID: US5707586A
- Status: Granted
- Kind: A
- Application number: 08/574,613
- Filed: 1995-12-19
- Granted: 1998-01-13
- Earliest claimed: 1995-12-19
- Assignees: CRS Holdings, Inc.
- Inventors: Fred W. McMann
- Web page: https://patentgrep.com/patent/US5707586A

## CPC

- C22C 38/26: with niobium or tantalum
- C22C 38/60: containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

A ferritic stainless steel alloy is disclosed having a unique combination of machinability, cold-formability, weldability, and corrosion resistance. The disclosed alloy has the following weight percent composition. ______________________________________ wt. % ______________________________________ Carbon 0.08 max. Manganese 1.00 max. Silicon 1.00 max. Phosphorus 0.045 max. Sulfur 0.030-0.30 Chromium 10.5-11.75 Molybdenum 0.50 max. Copper 0.50 max. Nickel 0.50 max. Aluminum 0.10 max. Columbium 10 .times. C to 0.80 ______________________________________ The balance is essentially iron. The novel alloy is particularly suited for components used in automotive fuel and exhaust systems. A number of such components made from the aforesaid alloy are also disclosed.

## Claims

### Claim 1

A ferritic stainless steel alloy having a unique combination of cold-formability and machinability, said alloy consisting essentially of, in weight percent, about:
______________________________________ wt. % ______________________________________ Carbon 0.08 max. Manganese 1.00 max. Silicon 1.00 max. Phosphorus 0.045 max. Sulfur 0.030-0.30 Chromium 10.5-11.75 Molybdenum 0.50 max. Copper 0.50 max. Nickel 0.50 max. Aluminum 0.10 max. Columbium 10 .times. C to 0.8 ______________________________________
and the balance is essentially iron.

### Claim 2 (depends on 1)

An alloy as recited in claim 1 which contains at least about 0.030% sulfur.

### Claim 3 (depends on 1)

An alloy as recited in claim 1 which contains not more than about 0.060% sulfur.

### Claim 4 (depends on 1)

An alloy as recited in claim 1 which contains at least about 0.30% nickel.

### Claim 5 (depends on 1)

An alloy as recited in claim 1 which contains not more than about 0.030% carbon.

### Claim 6

An article of manufacture comprising a metallic body having an axial bore formed therein and a plurality of threads formed on said metallic body whereby said metallic body can be threaded onto a second article having a mating thread, said metallic body being formed of a corrosion resistant, ferritic steel alloy having the following weight percent composition:
______________________________________ wt. % ______________________________________ Carbon 0.08 max. Manganese 1.00 max. Silicon 1.00 max. Phosphorus 0.045 max. Sulfur 0.020-0.30 Chromium 10.5-11.75 Molybdenum 0.50 max. Copper 0.50 max. Nickel 0.50 max. Aluminum 0.10 max. Columbium 10 .times. C to 0.80 ______________________________________
and the balance is essentially iron.

### Claim 7 (depends on 6)

An article of manufacture as recited in claim 6 wherein the threads are internal threads formed within the axial bore of the metallic body.

### Claim 8 (depends on 7)

An article of manufacture as recited in claim 7 wherein the metallic body has an external surface and a plurality of flat surfaces formed on said external surface whereby a tool can be applied to said metallic body for turning said metallic body as it is threaded onto the second article.

### Claim 9 (depends on 6)

An article of manufacture as recited in claim 6 wherein the metallic body has an external surface and the threads are external threads formed on the external surface of the metallic body.

### Claim 10 (depends on 9)

An article of manufacture as recited in claim 9 wherein the metallic body has a plurality of flat surfaces formed on said external surface whereby a tool can be applied to said metallic body for turning said metallic body as it is threaded onto the second article.

### Claim 11 (depends on 6, 7, 8, 9, 10)

An article of manufacture as recited in any of claims 6-10 wherein the alloy contains at least about 0.030% sulfur.

### Claim 12 (depends on 11)

An article of manufacture as recited in claim 11 wherein the alloy contains not more than about 0.060% sulfur.

### Claim 13 (depends on 11)

An article of manufacture as recited in claim 11 wherein the alloy contains at least about 0.30% nickel.

### Claim 14 (depends on 13)

An article of manufacture as recited in claim 13 wherein the alloy contains not more than about 0.030% carbon.

### Claim 15 (depends on 2)

An alloy as recited in claim 2 which contains at least about 0.30% nickel.