US882162A - Method of hardening steel. - Google Patents

Description

inch.

.steel of any WILLIAM PAINTER, OF ALLEGHENY, PENNSYLVANIA.

METHOD OF HARDENING STEEL.

Specification of Letters Patent.

Patented March 17, 1908.

Application filed April 13, 1907. Serial No. 363,099.

To all whom it may concern.

Be it known that I, VVILLIAM A. PAINTER, of Allegheny, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Methods of Hardening Steel, of which the following is a specification.

.My invention relates to a new and improved method of hardening steel and more particularly to a new method of hardening cast or tool steel, whereby a piece of such size and configuration may be hardened at one or more points or portions and the balance left soft or unhardened. ','II1 carrying out 'my method .of hardening the piece of steel to be treated is first partially inclosed or shielded by a flexible covering of any suitable material that will stand a hardening temperature. I prefer to employ thin sheet iron or thin pieces or sheets of steel for the protecting material. In practice thethickness of this flexible'covering material varies from .004 to t, of an -I.I1 no case should thethickness of the material be such as to prevent a practically uniform heating of the article while in its cover and a quick cooling of the prote'cted portion or portions. In other words the thickness of the covering employed should be such as not to prevent a graduated heating and a graduated cooling of the piece being treated, whereby a wide variance in temperature producing a strain between the exposed and covered parts -is avoided. A coveringformed of thick or rigid plates or plates so .thick as to be rigid or vice versa would produce such a variance in temperature between the protected and unprotected I arts that a proper graduated tempering or hardening of the parts could not be effected. The employment of thick lates would cause a contraction of the metal and consequently a strain or crack at the line of juncture of the hardened and unhardened portions.

The coolingof the protected portion or portions should be qluick as stated, butthe said portions will coo somewhat more slowly than the exposed portion or portions. This will prevent any undue strains in the metal. This shield or covering covers only that portion or portions of the article that are to re-' :nain soft, while the portion or portions to be hardened are left exposed. The covering being preferably thin flexible metal may be readily applied to an article of any size or shape, and cut or bent in such a manner as and being able to accurately After the piece being treated to expose the portion or portions of the article to be hardened. The sheet or sheets constituting the covering should be fitted close to the surface of the article, following the contour of the article, and are suitably fastened by rivets, wires, or other suitable means.

The next step in the process is to subject the partially. covered or protected article to the action of a proper hardening heat. This is done in the manner usually followed in hardening steel. The thin covering does not interfere 111 any way in the operation of heat ing the article to the desired hardening tent perature, the operator having perfect control determine the proper heat. has reached the proper temperature for hardening, the piece together with its covering is immediately quenched in any suitable cooling-bath, preferably .clear water. Upon the removal of the covering after the quenching step just described, it will be found that the exposed portion or portions of the steel will be hardened and the protected portion or portions soft.

B the employement of my method of hardening, 'I. practically eliminate all risk of breakage, cracking and warping in the ooeration of hardening and in addition thereto,

prolong the life of the treated article by having in a finished piece only those portions hardened that are desirable to he hardened, that is to say, the working or wearing surfaces, and leaving the other portion or portionssoft. The hardened portions being backed up by the soft steel will produce in almost every hardened steel article much better results than if the article were hardened throughout as is the prevailing practice.

While my method is particularly applicable for hardening pieces or articles of steel of large size, such, for example, as large, dies employed in the making of silverware, brassware and large sectional dies for electrical work, it may be advantageously employed for hardening any size or shape.

By my method of hardening, the operator can define with great accuracy the surfaceto be hardened, even to a 312' of an inch. I For example, a circular area may be hardened around-a square opening or a square area hardened around a circular opening or any irregular shape.

the quenching and the removal of the cover- Under my method, after ing pered or drawn usual manner.

method the color 5 hardened portions the hardened and soft portions.

' ,"What I clann is:

as above described, the steel is tem- With steel treated under my uated cooling suitable hardness in the will first appear on the defining with accuracy The herein-described method of hardening in presence of a piece of steel to implart hardness to a por- 10 tion of the steel, Whic that portion of the by a thin covering not prevent a graduated heating and a gradconsists in protecting piece not to behardened VVithesses1;

of a thickness that will YV. G.

of the piece and leavingiexts thin covering to a temg the piece and its cov- In testimony whereof I aflix'my signature tWo Witnesses. WILLIAM A. PAINTER MARGARET HUGHES,

Do OLITTLE