US2516737A - Hot-rolled binary zinc-titanium alloy - Google Patents

Description

Patented July 25, 1950 UNITED I 2,516,737 I HOT-ROLLED BINARY ZINC-TITANIUM ALLOY 1 Thomas C." Wilson, Washington, D. 0., assignor to The New Jersey Zinc Company, New York, N. Y., a corporation of New Jersey No Drawing. Application January 15, 1944, Serial No. 518,418

' 2 Claims. 1

This invention relates to binary zinc-titanium alloys, and particularly to the alloys disclosed in my copending United $tates patent application Ser. No. 460,933, filed October 6, 1942, noW aban' 2 loys at temperatures of from 190 to 300 C.,,temperatures of from 200 to 235 C. giving very satisfactory results. The hot rolling or mechanical working of the invention may be a finishing opdoned. The present invention is concerned with 5 oration consistin of say three or more passes the working of such alloys and contemplates certhrough the rolls, and may be preceded by either tain improvements in the mechanical working cold or hot rough rolling. and especially the rolling of such alloys. Creep'resistance or creep rate may be measured The binary zinc-titanium alloys disclosed in and directly expressed as the precent elongation my aforementioned patent application contain or creep of a standard test piece during a'unit of from 0.01% to 1.6%, and preferably from 0.05% s time, say one day, when subjected to a. dead load to 0.3%, titanium, with thebalance zinc, prefof, say, 8000 poundsper square inch (p. s. i.) at era-bly high-grade zinc, although zinc of the constant room temperature 0.). When the grade commonly used in commercial rolled zinc creep rate is so expressed, the lower values (permay be used. These alloys are conveniently l5 cent/days) represent the higher creep resist,- manufactured by first preparing a zinc-titanium 'ance. I prefer to express the creep resistance hardener by adding about 4% of titanium metal' as the inverse creep rate which is the number of to molten zinc andholding under a boric acid units of time, say days, required to produce an cover, with frequent stirring, at 750 CL until the elongation or creep of one percent (days/pertitanium is dissolved. The desired titanium con- 2 cent), whereby the more creep resistant alloy tent in the binary zinc-titanium alloy is then (or material) has the higher inverse creep rate. readily obtained by adding the calculated amount The following Table I shows the mechanical of this hardener to a predetermined weight of properties and superior inverse creeprates of molten zinc. c three (Nos. 1, 2 and 3) hot-rolled zinc-titanium The binary zinc-titanium alloys of my afore- 25 alloys of the invention, contrasted with a zincmentioned patent application, when transformed copper alloycontainin 1% copper. The zincto sheet or strip by suitable rolling procedure, titanium alloys were hot rolled to 0.02" in a 12" possess high creep resistance (resistanceto cold diameter mill with a final coil temperature of flow), namely, resistance to prolonged static about 200 C. The bars rolled quite easily and loads well below the ultimate limit. Cold work- 0 produced strip of good surface quality, The bi or rolling tends to decrease the creep resistrolled strips were subjected to the normal routine ance of these alloys, but their normal high creepv mechanical property tests including determinaresistance can be substantially restored by subsetions of creep rate.

' Table I Tensile Elon- Inverse Creep Rates,D ays Analyzed s... e mend than in iiiiiiii Per Cent Gauge scope namic per,

T1 Bal- In j Hard- Ductil- Per amezn Cent With Across With Across With Across 8,000 12,000 15,000 Grain Grain Grain Grain Grain Grain p. s. i. p. s. i. p. s. i.

0.023 119- .0. 320 -30. 2% 2 19,500 27,600 33.2 13.3 24.2 0.055 0.0039 0.021 20 0.300 37 3 2 20,100 20,900 29.5 12.0 100.0 1.05 0.023 0.022 22 0.295 40 4 2 21,300 30,000 28.3 11.3 1,120.0 4.05 0.077 0.018 17 0.280 40 3% 2 23,700 30,000 35.0 8.7 1.95 0.10 NoTest 1 Alloys prepared with 99.99%pure zinc.

2 Values represent the diameter of the bend in multiples of sheet thickness.

3 Hot rolled, analogous to Zn-Ti treatment.

Small values indicate better bending properties.

4 Tests not run to the usual fi-per cent total elongation. Values recorded represent the slope of the line joining the origin of the curve of time vs. elongation with the final recorded point-values probably lower than true values.

cally working or rollin these z'inc titaniumal- 1 The data in Table I shows the remarkable "creep resistance of the hot-rolled alloys of the invention. At moderate loads (e. g. 8000 p. s.-i.)

the creep resistance of these alloys is astonishingly high, particularly in the case of the alloy containing 0.23% titanium (No. 3).

As hereinbefore stated, I have found that the temperature of rolling exercises a very great effect upon the creep resistance or the rolled strip. With a rolling temperature around 0., the inverse creep rate of a zinc-titanium alloycontaining 0.12% titanium was 0.033 (days/percent) under a load of 12,000 p. s. i. With a rolling temperature around 190 C. the inverse creep rate of the same alloy was 0.72, and with a rolling temperature of around 210 C. the inverse creep rate was 1.76. The effect of rolling temperature upon the creep resistance of the rolled alloy is shown in the following tables in which Table II gives the schedule of the rolling operations orv 5 specimens of a zinc-titanium alloy containing 0.12% titanium, and Table III gives the inverse creep resistance rate of the resulting rolled strips.

The preliminary or rough rolling schedule was the same for each specimen (A to E) and reduced the specimens from slabs 7"x14"x1 :to agauge of approximately 0.09" in ten passes through therolls. The first horizontal line of Table II is the temperature of the rolls, the second horizontal line is the starting temperature of the alloy specimens, D and E- being preheated in order to attain the higher final coil temperatures. The specimens were given three passes (four for A) through the rolls to efiect a reduction in gauge from about 0.09" to about 0.02" (0.015" for C). The last horizontal line of the table is the final coil temperature of the rolled strip after the final rolling pass.

Table II A B C D E 140-160" C. 170-190 G. FIG-190 C. 170-190 0. 170-190 0. Room Room Room 140 0. 140 C.

Table III Inverse Final coil Creep Rate. Specimen Tgntgeer' i z gg p. s. 1.

The influence of hot rolling upon the creep resistance of the zinc-titanium alloys is further illus'trated by Table IV, in which the hot rolled alloy (0.12 titanium) is contrasted with the cold vrolled alloy, and with hot and cold rolled zinc .copper alloy (1% copper).

From the foregoing examples, it will be seen that the hot rolled or worked alloys of the inventionpossess remarkably high creepresistance. The line of demarcation between cold and hot rolling, so far as the effect upon creep resistance is concerned, seems to be in the neighborhood of 160-180 C. With rolling temperatures below that temperature range, the creep resistance is not unusual. With rolling temperatures above that temperature range, a significant and sharp increase in creep resistance is attained. The contemplated conditions of hot rolling can be established by preheating the alloy or by heating the rolls so that the thermal conditions during rolling impart a final temperature of 190 to 300 C. to the alloy passing from the final roll (final coil temperature). It is not necessary, and in practice not likely, that the contemplated hot rolling temperature be maintained during each pass of the complete rolling schedule. The advantages of the invention are satisfactorily attained where the final coil temperature is within the contemplated hot rolling temperature range.

The data in Table IX reveal theunusual effect in the zinc-titanium alloy of cold rolling effecting a softening and weakening as compared with hot rolled material. The work hardening revealed in the 1% copper alloy is, of course, the normal result.

Photomicrographs' of the hot and cold rolled zinc-titanium alloy of the invention show the metal to he apparently free of cold working in the cold rolled state, an observation that is consistent with the physical properties of the metal.

Redraw tests showed that as many as four redraws could be made without intermediate anneals, and with at least recovery of unfractured material. Thus, it is evident that the alloy does not work harden. Another interesting property of the alloy is the appearance of a high population of basal planes normal to the rolling plane and lying in the rolling direction.

Contrary to experience with zinc, the zinctitanium alloy has been found not to grow excessively large grains when annealed. Anneals up to, 24 hours duration at temperatures up to 400 C. failed to produce relatively coarse grain structures. Moreover, it has been found that ductility and other properties are not harmed by annealing and, significantly, the high creep resistance noted inthe hot rolled alloy which was sharply reduced by cold working was found to be largely restored bysuitable heat treatment.

I claim:

1. A. binary zinc-titanium alloy product containing from 0.01% to 1.6% titanium and having been subjected to a finishing treatment consisting of hot rolling at a temperature within the range of C. to 300 C.

2. A binary zinc-titanium alloy product containing from 0.05% to 0.30% titanium and having been subjected to a finishing treatment consisting of hot rolling at a temperature within the range of from 200 C. to 235 C.

THOMAS C. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 979,393 Rossi Dec. 20, 1910 1,020,512 Rossi Mar. 19, 1912 1,835,450 Anderson Dec. 8, 1931 1,888,567 Pierce Nov. 22, 1932 2,048,288 Pierce Jul 21, 1936 2,169,441 Winter Aug. 15, 1939 2,317,179 Daesen Apr. 20, 1943 OTHER REFERENCES Metals Handbook, 1939 edition, pages 1737, 1765; pub. by American Society for Metals, Cleveland, Ohio.

. Certificate of Correction Patent No. 2,516,737 July 25, 1950 THOMAS 0. WILSON It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 9, for precent read percent; line 51, for shows read show; column 4, line 16, for Table IX read Table IV;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 17th day of October, A. D. 1950.

THOMAS F. MURPHY,

Assistant Gommz'ssz'oner of Patents.

Claims (1)

1. A BINARY ZINC-TITANIUM ALLOY PRODUCT CONTAINING FROM 0.01% TO 1.6% TITANIUM AND HAVING BEEN SUBJECTED TO A FINISHING TREATMENT CONSISTING OF HOT ROLLING AT A TEMPERATURE WITHIN THE RANGE OF 190*C. TO 300*C.