US3320102A - Method of shaping metal - Google Patents

Description

United States Patent 3,320,102 METHOD OF SHAHNG METAL Perry J. Murphy, In, McCandles Township, Allegheny, County, and John T. Shultz, Whitehall Borough, Pa.; said Shnltz assignor to United States Steel Corporation, a corporation of Delaware, and said Murphy assignor to The Van Dorn Iron Works Company, Cleveland, Ohio, a corporation of ()hio No Drawing. Filed Nov. 6, 1964, Ser. No. 4(i9,616

2 Claims. (Cl. 148-131) This invention relates to a method of shaping metal and more particularly to a method of shaping ferrous metal articles. The term ferrous metal as used herein refers to iron and iron alloys.

It is desirable for many purposes to manufacture high strength, i.e. 100,000 p.s.i. yield strength and higher, structural members with configurations designed to compensate for under load conditions. As an illustration, structural members in buildings may be advantageously bent in manufacture so that they will be flat when loaded and will not sag as they may otherwise do if initially constructed flat. Similarly, bent steel beams, usually referred to as precarnbered, are useful as structural supports for flat bed trucks, particularly those with a low center of gravity, to avoid problems of sagging under load. However, as metals of higher strength are developed, forming operations become increasingly diihcult.

Preshaped metal members have been manufactured in the past by cold forming processes wherein the metal member is plastically deformed beyond its yield point into a desired configuration. This manner of shaping is not, however, practical with sections of very high strength material, gross size and complex shape. The difliculty, for example, in bending an H beam of steel having 100,- 000 psi. yield strength is very great. The forces required to shape such a member are beyond the capacity of conventional equipment. Moreover, even if it were possible to apply sufficient forces, the webs of the beams may buckle. An additional disadvantage of cold forming in this manner is that heat treatments at relatively high temperatures (recrystallization temperature, i.e. above the A temperature) may be necessary to remove the effects of cold Working.

The present invention provides a relatively simple method of shaping metal articles which is particularly advantageous with high strength materials. According to the invention, metal articles are bent or otherwise shaped into the desired configuration within the elastic lirnit of the material and the article is then restrained in that position while it is heated at a temperature below its recrystallization temperature for a time suflicient to substantially relieve bending stresses developing during shaping. The stress relieved article assumes the desired configuration and can then be cooled to permit handling.

As an illustration, steel structural members which may be hot worked, e.g. hot rolled or thermally treated products or even forgings or castings as well, are deflected by bending without exceeding the elastic limit, and then, while held in the bent position, are heated to relieve bending stresses in the steel. One convenient method of bending structural members is to align two members side by side and insert measured separators at proper intervals between them as the members are jacked together. After achieving the proper deflection (camber), a clamping device is slipped over the opposite sides of the members and the jacks removed. Alternatively, the ends of the structural members can be clamped together and the center portion jacked apart and separators inserted between the members for spacing. It may be convenient at times to clamp the center portions together and separate the ends to the desired deflection. In any event, after the steel has been shaped as desired within its elastic limit, it is restrained in the new position and heated to relieve bending stresses. The time and temperature are selected so that the shaping stresses are substantially eliminated in a reasonable period of time and the member will remain in substantially the desired configuration after cooling.

For ferrous metal articles, it has been determined that temperatures within the range of from above about 900 F. to below the critical, i.e. transformation temperature of the material, and soaking time of one-half to three hours may be satisfactorily used. In this connection, it is possible to perform stress relieving and tempering concurrently since significant tempering may be effected at the stress relieving temperatures used. In this way, heat treating to develop mechanical properties and shaping can be combined in the same operation.

Often, it will be impractical to remove all of the residual stress in the metal member and full relief of the bending stress will not occur until the restraints are removed from the member after cooling from stress relie' ing temperature and the member is permitted to spring back to relieve itself of these residual stresses. In such cases, it is necessary to overbend the member so that when the majority of the bending stresses are relieved during the stress relieving heat treatment, the member will possess the desired camber or deflection after spring back.

Metal plates, tubings, etc. may also be treated to provide a desired configuration by bending or otherwise shaping the material within its elastic limit. By practicing the invention, such articles may be bent and shaped within their elastic limit with considerably less force than that necessary in cold forming by plastic deformation wherein the material is deformed beyond its yield point. If, after shaping, the material is held at the stress relieving temperature for suificient time to relieve the majority of the stresses introduced by shaping, it will maintain its new configuration after cooling to room temperature. It may also be desirable to practice multiple bending sequences in which an article is shaped in increments and stress relieved after each increment until the final desired configuration is achieved.

The following example will illustrate the preferred practice of the invention:

Two 30-foot as quenched, H-beam sections of a highstrength steel having the following composition:

are placed side by side. Spacers are inserted between them at intervals and the centers are jacked together and then clamped. The beams are deflected with the application of relatively little force within their elastic limit and without exceeding their yield strength. The assembly is then heated in a tempering furnace to a temperature within the preferred range of 1050 F. to 1275 F. for one hour after which it is removed from the furnace and allowed to cool. Upon cooling to room temperature, the clamp and spacers are removed and the beams spring back one eighth inch. However, a camber of one and three-quarter inches over the length of the beam is produced in the steel members.

It is apparent from the foregoing description that various changes and modifications may be made without departing from the invention. Thus, for example, shapes If titanium, zirconium or other metals or alloys thereof may be made by following the procedure described heren. In all cases, the metal article is bent or otherwise haped without exceeding its elastic limit, after which it s restrained in the new configuration and heated and naintained at a temperature for a time sufiicient to reieve stresses formed during shaping so that upon coolng to room temperature the article maintains its new :onfiguration. The cross section of the articles treated nay vary and the force required for shaping will vary [180; these forces are readily determined by those skilled n the art and are dependent on the length, original shape ll'l'd desired configuration as well as the mechanical prop- :rties of the metal member.

We claim:

1. A method of making shaped ferrous material srtucvural members having yield strengths of at least about [00,000 psi. comprising shaping the member within its :lastic limit without plastically deforming the member )y exceeding the members yield strength, restraining the member in said shaped configuration, heating the member to stress relieving temperature in the range of from about 900 F. to the A temperature, maintaining the member at stress relieving temperature until stresses caused by shaping are substantially eliminated and thereafter cooling and unrestraining said member to permit handling.

2. A method according to claim 1 wherein said article is heated to stress relieving temperature in the range of 1050 to 1275 F.

References Cited by the Examiner UNITED STATES PATENTS 663,156 12/1900 Budke 148-131 X 2,666,723 1/1954 Stewart 14812 2,745,658 5/1956 Gaskins l4812 DAVID L. RECK, Primary Examiner.

HYLAND BIZOT, Examiner.

H. SAITO, Assistant Examiner.

Claims (1)

1. A METHOD OF MAKING SHAPED FERROUS MATERIAL STRUCTURAL MEMBERS HAVING YIELD STRENGTHS OF AT LEAST ABOUT 100,000 P.S.I. COMPRISING SHAPING THE MEMBER WITHIN ITS ELASTIC LIMIT WITHOUT PLASTICALLY DEFORMING THE MEMBER BY EXCEEDING THE MEMBER''S YIELD STRENGTH, RESTRAINING THE MEMBER IN SAID SHAPED CONFIGURATION, HEATING THE MEMBER TO STRESS RELIEVING TEMPERATURE IN THE RANGE OF FROM ABOUT 900*F. TO THE A1 TEMPERATURE, MAINTAINING THE MEMBER AT STRESS RELIEVING TEMPERATURE UNTIL STRESSES CAUSED BY SHAPING ARE SUBSTANTIALLY ELIMINATED AND THEREAFTER COOLING AND UNRESTRAINING SAID MEMBER TO PERMIT HANDLING.