US2189198A - Copper-titanium alloy - Google Patents

Description

"Patented Feb.f6, a 139,193

UNITED STATES PATENT, OFFICE g 2,189,198 i a corms-TITANIU ALLOY George F. Comstock, Niagara Falls, N. Y., mm?

- .to The Titanium Alloy Manufacturing. Compan'y, New York, N. 1a,; corporation of Maine I No Drawing. Application.lune 28, 1938,

, l Serial 190.218.2150

' 3 Claims (01. rs-Jen My invention relates generally to copper alloys in which copper is the major constltuent, and particularly to alloys containing copper; titanium andsilicon which have been subjected'totemper- 5 hardening treatments that develop increased hardness, strength and" electrical conductivity,

particularly in respect to these ternary copper,

alloys in the form of castings. v

The object of my invention among other things, to improve both the hardness and the electrical conductivity of copper-titanium alloys,

so that heat-treated castings of this ma-,

terial may preferably serve with satisfaction as electrodes in welding machines.

II The machines referred to are those usually employed for the fabrication of automobile bodies from steel sheets, or for closing the seams of tubes made of steel strips, or similar purposes. The welding tips on these machines which convey electric current through the steel sheets to fasten them together by heat and pressure must be hard enough not to deform, and must also have sufficient electrical conductivity so as not to become overheated by the passage oi. the current which would also be likely to lead to deformation and poor welding.

Copper-titanium alloys containing from about 0.75% to about 2% or moretltanium are known to be hardenable by heat treatment to above 100 on the Brinell scale, which is suflicient for the I welding tips referred to, but in the form of castings at least they are too lowin conductivity. The copper-titanium-silicon alloy described ,in

. my U. S. Patent No. 2,086,604 of July 13, 193,7.has sufllciently' high conductivityfor this purpose, but is slightly deficient in hardness. in the form of heat-treated castings.

I have now discovered that by the addition of about 0.2 to 0.5% chromium to that alloy con- 40 taining about,0'.8 to 1% titanium, 0. 2 to 0.45% silicon, andbal'ance copper, castings maybe made which, after proper heat-treatment, are

sufficiently hard and high in conductivity to serve with satisfaction as tips in certain kinds '45 of welding. machines.

The heat-treatment required to secure the best properties in castings of this new and improved alloy is generally a quench in water after hold-' ing at 1 650 F..fOI about 1 t0 2 hours, followed by 5 tempering at 900 or 950 F. for 16 to 24 hours.

The hardness after this treatment is about 105 to 115 Brinell; and the conductivity about 40 to The iron content however mustbe very low to reach 50% conductivity, as if such iron content approaches 0.2%, the conductivity may not be over 30%. Other impuritiessuch as tin,

zinc, aluminum, etc, also impair seriouslypthe conductivity. i I

If high conductivity is=desirable and the hardne'ss need notbe over Brinell, the castings 5 i otthis improved. alloy may be merely tempered as it comesfrom thesand without aninterven ing quench.' For example, alloys containing 0.79

to 1.01% titanium,0.26to 0.41% silicon, 0.17.,to

0.19% chromium, and 0.034 to 0.05% iron, and 10 1 the balance copper, merely tempered 15 to 35' hours at-900 to 950 F. were found to have 51.5

' to 61% conductivity, and Brinell hardness of 90 l 0127 to 28%. n tempered at sown, these 25,

copper-titanium alloys with low silicon lose both hardness and conductivity, whereas the alloys with the herein specified silicon content have I the 0 best properties after tempering at about 900 1!- 0.4% chromium, with the balancehcopper, but considerable variation from these proportions maybe desirable depending on whether hardness a5 i 35 or conductivity ismost important. l

' Impurities such as iron, tin, etcshould be less than 0.1%.

If hardness is desiredmorethanconductivity,the l l titanium may be raised and thesiliconreduced- Chromium above 0.6% is not generally desirable 40 in this improved alloy. The permissible range of composition of the alloys embracedby-my invention may, there1'ore be specified asabout 0.6. to 1.5% titanium, 0.1 to-0.6% silicon, 0.1to0.6%

chromium and the balance copper, and preierably with no impurity above about 0.1%.

I As examples of the commercialproduction of castings of my'new and improved! alloy which have been used successfully in weldingmachines,

the following maniacturingrecords are presented .50 1 1 as typical of my invention: i

Example A.-A chargeot 138 lbs. of purecopper was first melted in a Tercod crucible using a glass flux in an oil-fired, furnace. After super-,

nat e glass" was removed, and the copper 55 My preferred improved alloy to obtain the best combination of hardness and conductivity may be set as about 0.9% titanium, 0.1% silicon, and.

was deoxidized with /2 lb. a silicon-calciummagnesium-copper alloy, and 10.2 lbs. of 10% chromiumcopper, and then 0.6 lb. of refined silicon were stirred in. Then 1.7 lbs. of metallic titanium were added by means of a graphite phosphorizer or inverted cup; when this addition of titanium had dissolved completely, the crucible was withdrawn from thefurnace and its contents poured into molds. The analysis 01 these castings showed 0.79% titanium, 0.41%

silicon, 0.19% chromium, and about 0.05% iron andthe balance copper; after heating same at 1650 F. for 1 hours, quenching in water, re-

heating at 950 F. for 16' hours and cooling in air,

1 acasting was found to have 48.9% conductivity and a Brinell hardness or 109.

Example B.Another casing of my improved alloy was much larger, and required the contents of seven crucibles mixed in a large ladle before the mold was poured. sisted of 1220 lbs. of gates and risers from previous castings of this'same alloy, 1440 lbs. copper deoxidlzd "by 12 lbs. of the same Si-Ca-Mg-Cualloy Leferred to in Example A., and treated with g 149 lbs. 10% chromium-copper, 3.2 lbssmetallic silicon, and 24 lbs. of titanium. A glass flux was used in each pot when melting and superheating, and was removed before making thealloy additions. This casting and a test-bar from the same ladle were heated to 1650 F..tor.1 hours,

The charge 'conquenched in water, reheated to 900 F. for 10 hours and then cooled in air. The test-bar then showed 105 Brinell hardness and about 32% conductivity. It analysis was 0.92% titanium, 0.39% silicon, 0.54% chromium, and 0.183% iron, with 5 the balance copper; the iron" content was 1500- high. for the best conductivity.

Although these examples refer to castings, my

improved alloy has also been forged successfully,

and my invention, involving only a new and im- 10 proved composition, may be applied also to rolled or-forged bars, wire, or sheets, which may be heat-treated. either before or after fabrication.

Ijclaim as my invention: v 1.]A heat-hardened copper alloy containing 1 titanium from about 0.6 to 1.5%,"silicon from about 0.1 to 0.6%, chromium from about 0.1 to

0.6%, and the balance consisting substantially entirely of copper. 2. A heat-hardened copper alloy containing titanium about 0.9%, silicon about 0.4%, chromium about 0.4% and thebalance consisting substantially entirely of copper.

.3. A tempered copper alloy containing from about 0.79 to 1.01% titanium, 0.26 to 0.41% silicon, 0.17 to 0.19% chromium, with the balance -consisting substantially entirely of copper, and

having from about 51.5 to 61% electrical conductivity and Brinell hardness of 90 to 95.

GEORGE F. COMSTOCK.