US3148055A - Zirconium alloys - Google Patents

Description

United States Patent 3,148,055 ZIRCONEUM ALLOYS Stanley Kass, Pittsburgh, Wilber W. Kirk, Wiliriiisbiirg, and Donald W. Bright, Pittsburgh, Pa, assignors to Westinghouse Electric orporatioii, East hittsbuigh,

total of from 0.1% to 2% by Weight of at least one metal from the group consisting of iron, nickel, and chromium, at least 0.11%, but not exceeding 0.25%, by Weight of oxygen, silicon not exceeding 0.012%, carbon not exceeding 0.05%, the balance being zirconium and less than Pin, a corporation oi Pennsylvania 5 0.5%, by weight of incidental impurities such as nitrogen No Drawing. Filed Apr. 14, 1960, Ser. No. 22,133 and carbon, as Well as small amounts of non-detrimental 3 Cluims. elements This invention is directed to novel zirconium alloys espeslally import'fmt alloy made in eeeordahce W having high resistance to corrosion and good mechanical this invention is a family of alloys consisting essentially strength of from 1.3% to 1.6% by vveight of tin, from 0.07%

In US. Patent No. 2,772,964, issued December 4, 1956, t0 by welght 0f chromlumi from 012% to 040% and assigned to the assignee of the present invention, by Welght at least 9 but P exceeding there are disclosed alloys of zirconium that are character- 025% by Welght 9 Oxygen mckel not e i ized by highly desirable properties for many applications. 15 carbon not exceedmg 005%; h h f belhg The alloys of this US. patent have excellent properties and less than by welgnt of lhcldehtal lmpuntleeat room temperature and at elevated temperatures and The alloys descr bed above are particularly notable due have therefore found Wide application in industry, parto W capaclty for hydrogen absorption h ticularly in an environment of hot water or steam. 9 hlgh temPerature and f Thls h Zirconium and its alloys are almost without exception acteristic results in the retention of high mechanical subject to corrosion to a greater or lesser degree in the Strength m such ,envlrohmehts- Thus, the alleys h h presence of hot Water or steam. One of the products of empioyed m 9 and other h h Wherelh thls the corrosion reaction is hydrogen, and it has been found Partlcular combmatlon of phopertles 1S adVahtageousthat this hydrogen is absorbed by the remaining zircoon- The alloys of the PresenL Invention may hot forged, ium alloy mass The absorbed hydrogen adverssly hot rolled, hot extruded, or swagedtrom ingots thereof, aficicts the mechanical Strength of the members formed even with substantial amounts of nitrogen of the order from the zirconium alloy. The decrease in mechanical of 2 being present Carbon may he P 1h strength accelerates the failure of members which may of up to The hot Worked alloys have suliered corrosion to a relatively insignificant degree. be mafmy cold Worked to Produce members of deslred It is accordingly an object of the present invention to 3 final Slze and,shapeprovide Zirconiumbase alloys which possess gocd Cop The following examples are illustrative of the present rosion resistance, and in addition, have a decreased calrivemlon' In thes e examples Parts and Percentages pacity for the absorption of hydrogen; the alloys including glven for a composltlon are by Welghtin predetermined proportions the elements tin, chromium, EXAMPLE I iron, oxygen and zirconium.

Another Object f the invention is to provide a Zip An alloy of the following composition was prepared: conium-base alloy consisting of from 0.1% to 2.5%, by Percent weight tin, a total of from 0.1% to 2% by weight of Ti 13) 1'6 at least one metal from the group consisting of ron, Ch i 07 to 0.12 nickel, and chromium, troni 0.16% to 0.25 by vVeight, 40 Ni k l 004 to 008 oxygen, the alloy exhibiting good corrosion resistance I 0.09 to 016 to high temperature water and steam, high strength, and Oxygen 0125 good ductility. Some benefits are obtained if the oxygen Zi i Balance content is slightly below 0.16%, though it must be at 1 0 11% The nitrogen content did not exceed parts per It i a f th bj t f h i ti to id a million and carbon was less than 0.05%. Corrosion test zirconium-base alloy consisting of from 1.3% to 1.6%, coupons of this alloy Were P p y Shearing 0-030 by Weight f f 7% to 11 by weight f inch thick cold-rolled strip into samples 1 inch x 1.5 chromium, from 0.12% to 0.40%, of iron, a maximum inches and ahradihg the rough edges- The Surfaces of nickel and mall amounts of oxygen of from 50 Were chemically etched t0 remove inch per surface, 0.16% to 0.25%, the alloy exhibiting good corrosion thereby minimizing Surface contaminationresistance to high temperature Water and steam, high The Coupons were exposed to Wat r and 750 trength, d d d tilit F. steam, atmospheres which are corrosive to the alloy,

Other objects of the invention will, in part, be obvious and The Corrosion fate and hydrogen P P 0f the alloy d 111, i t, appear h i ft was measured. Similar coupons were made from a sub- In accordance with the present invention, there are stehtiahy identical alloy Containing y 0-085% y id d novel i d zircgnium-base ll h and these coupons Were also exposed to the same corrosive terized by high corrosion resistance to high temperature atmOSPheTeS- In the following Table the hydrogen Water and steam, good ductility, and low capacity for P P 0f the two alloys is compared; the y g P hydrogen absorption With resultant retention of high P values are Presented as a ratio of the hydrogen mechanical strength. These zirconium-base alloys consist sorbed by the alloys to the amount of hydrogen evolved essentially of from 0.1% to 2.5%, by Weight of tin, a in the corrosion reaction, in percent.

Table 1 Days in 680 F. water Days in 750 F. steam Oxygen 7 14 2s 56 84 112 140 168 196 224 252 7 14 28 42 98 126 154 33 3s 42 53 49 46 54 51 51 45 52 42 42 49 47 52 57 54 13 23 1s 22 13 i4 31 32 32 42 33 29 22 A greatly decreased absorptive capacity for hydrogen is manifest in the higher oxygen alloys in Table I above. The mechanical strength of the high oxygen alloys greatly exceeded that of the low oxygen alloys.

It has been found in working with the alloys of the general type described above, that limiting the nickel content to a maximum value of 0.007% appreciably reduces the hydrogen pick-up. Modifications of this low nickel alloy involving variations in the iron content indicate that increasing iron contents to about 0.25% and higher increases the hydrogen pick-up. Again, the benficial effect of oxygen in reducing or at least stabilizing the hydrogen pick-up can be demonstrated. The following Table II presents for a series of alloys having no significant nickel content, and in which the iron content was varied from a minimum of 0.120% to 0.336% while the oxygen content varied from a minimum of 0.090% to a maximum of 0.195%, the ratios (in percent) of the amount of hydrogen absorbed by the samples to that produced by the corrosion reaction.

capacity for hydrogen absorption during exposure to high temperature water or steam consisting of, from 0.1% to 2.5% by weight of tin, and a total of at least 0.1%, but not exceeding approximately 2% by weight of at least one metal from period 3 of the Periodic Table selected from the group consisting of iron, nickel, and chromium, at least 0.16%, but not exceeding 0.25%, by weight of oxygen, carbon not exceeding 0.05 the balance being zirconium and less than 0.5% by Weight of incidental impurities.

2. A zirconium-base alloy having a decreased ability to absorb hydrogen during exposure to high temperature water or steam consisting of, from 1.3% to 1.6% by weight of tin, from 0.07% to 0.12% by weight of chromium, from 0.04% to 0.08% by weight of nickel, from 0.09% to 0.16% by weight of iron, at least 0.16%, but not exceeding 0.25%, by weight of oxygen, carbon not exceeding 0.05%, the balance being zirconium and less than 0.5% by weight of incidental impurities.

3. A zirconium-base alloy having a decreased absorp- From Table II it will be noted that the removal of nickel from the alloy sample 1 has substantially lowered the hydrogen pick-up (compare with Table I). Sample 2 indicates the increased hydrogen pick-up which results from increasing the iron content. Samples 3, 4 and 5 show the stabilizing effect, insofar as hydrogen pick-up is concerned, of increased oxygen upon alloys containing increasing amounts of iron. The corrosion resistance of the samples of the alloys shown in Table II is not affected to any substantial degree by the increased amounts of iron and oxygen therein.

The relatively high oxygen level of the alloys of this invention permits a greater tolerance in minor variations of alloying constituents, such as iron, while maintaining excellent corrosion resistance and low hydrogen pick-up. It will be understood that the above description is only exemplary and not in limitation of the invention.

We claim as our invention: 1. A workable zirconium-base alloy having a lowered tive capacity for hydrogen when exposed to high temperature water or steam and containing a relatively large amount of iron therein, consisting of, from 1.3% to 1.6% by weight of tin, from 0.07% to 0.12% by weight of chromium, from 0.12% to 0.40% by weight of iron, at least 0.16%, but not exceeding 0.25%, by weight of oxygen, carbon not exceeding 0.05%, less than 0.007% nickel, the balance being zirconium and less than 0.5% by weight of incidental impurities.

References Cited in the file of this patent UNITED STATES PATENTS 2,772,964 Thomas et al Dec. 4, 1956 3,005,706 Thomas et al Oct. 24, 1961 OTHER REFERENCES Journal of the Electrochemical Society, vol. 106, No.

3, March 1959 (pages 131-184).

Claims (1)

1. A WORKABLE ZIRCONIUM-BASE ALLOY HAVING A LOWERED CAPACITY FOR HYDROGEN ABSORPTION DURING EXPOSURE TO HIGH TEMPERATURE WATER OR STEAM CONSISTING OF, FROM 0.1% TO 2.5% BY WEIGHT OF TIN, AND A TOTAL OF AT LEAST 0.1%, BUT NOT EXCEEDING APPROXIMATELY 2% BY WEIGHT OF AT LEAST ONE METAL FROM PERIOD 3 OF THE PERIODIC TABLE SELECTED FROM THE GROUP CONSISTING OF IRON, NICKEL, AND CHROMIUM, AT LEAST 0.16%, BUT NOT EXCEEDING 0.25%, BY WEIGHT OF OXYGEN, CARBON NOT EXCEEDING 0.05%, THE BALANCE BEING ZIRCONIUM AND LESS THAN 0.5% BY WEIGHT OF INCIDENTAL IMPURITIES.