# US 4,398,966 A · Corrosion of type 304 stainless steel by laser surface treatment

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

- Number: US 4,398,966 A
- Document ID: US4398966A
- Status: Granted
- Kind: A
- Application number: 06/372,648
- Filed: 1982-04-28
- Granted: 1983-08-16
- Earliest claimed: 1982-04-28
- Assignees: Huntington Alloys, Inc.
- Inventors: Thomas J. Kelly; Joseph L. Nelson
- Web page: https://patentgrep.com/patent/US4398966A

## CPC

- C21D 1/09: by direct application of electrical or wave energy; by particle radiation
- C21D 6/004: {containing Cr and Ni}
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)

## Abstract

Surface treatment of stainless steel with pulsed beam from laser benefits resistance to corrosion in acid chloride media.

## Claims

### Claim 1

A process for enhancing the corrosion resistance of stainless steel comprising directing a pulsed energy beam onto a localized portion of a metal surface of stainless steel to rapidly heat the metal to at least the solid solution temperature and then chilling the thus heated metal to result in a quench rate of at least 1.times.10.sup.3 .degree.C. per second whereby the thus treated localized portion of the surface exhibits enhanced resistance to corrosion.

### Claim 2 (depends on 1)

A process as set forth in claim 1 wherein the metal is heated to at least the melting temperature.

### Claim 3 (depends on 1)

A process as set forth in claim 1 wherein the chill rate is at least 1.times.10.sup.5 .degree.C. per second.

### Claim 4 (depends on 1)

A process as set forth in claim 1 wherein a pulsed laser is employed and the average operating power of the laser is at least 50 W.

### Claim 5 (depends on 1)

A process as set forth in claim 1 wherein the stainless steel is of the composition known as Type 304.

### Claim 6 (depends on 1)

A process as set forth in claim 1 wherein the localized portion that is heated is of about 0.254 to 1.27 mm average diameter.

### Claim 7 (depends on 1)

A process as set forth in claim 1 wherein the pulse rate is 100 to 200 pulses per second.

### Claim 8 (depends on 1)

A process as set forth in claim 1 wherein the laser wavelength is 0.5 to 11 microns.

### Claim 9 (depends on 1)

A process as set forth in claim 1 wherein the chill rate is about 1.times.10.sup.6 to 1.times.10.sup.8 .degree.C. per second.

### Claim 10 (depends on 1)

A process as set forth in claim 1 wherein the travel speed of the beam relative to the metal is about 30 to 60 inches per minute.