US2061921A - Corrosion resistant tubes - Google Patents

Description

Patented Nov. 24,1936

UNITED STATES PATENT OFFICE CORROSION RESISTAN'T TUBES Edward W. Roath, Waterbury, Conn, asslgnor The Chase Companies, Incorporated, New Haven,-Conn., a corporation of Connecticut No Drawing. Application March 20, 1936, Serial No. 69,885 I Claims.

Ordinary straight or plainbrasses consisting solely of copper and zinc are subject to dezincification when the actual copper content ranges 15 between about 57% and about 85%. When' one or more other elements are added to straight brasses, the actual copper content dezincification range is usually different.

Straight brasses subject to dezinciflcation and having an actual copper content iro'nrabout 64% to about 85% consist entirely of alpha solid solution,- while those from about 64% down to about 57% consist of both alpha and beta solid solutions.- Special brasses containing one or more additional elements, such, for example, as silicon, aluminum, tin, manganese, etc., in addition to the copper and zinc. and having approximately the same degree of, saturation of the alpha solid solution or approximately equal relative proportions of the alpha and beta solid solutions as the straight brasses having an actual copper content from about 57% to about 85%, generally dezincii'y similarly to' 40 made of 76% 'copper, 2% aluminum and the balance zinc, it is found that this brass has astructure equivalent to a straight brass of about 69% copper, that is, the 76% aluminum-containing brass has a degree oi saturation of the alpha solid solution approximately equalto that which occurs in 69% straight brass. Therefore, the aluminum brass containing an actual copper.

content of 76% may be said to have an apparent copper content or structurally equivalent copper content of 69%.

' Investigation of various special brasses containing additional elements such as silicon, aluminum and other elements, showsthat the efiect of these additional elements follows a law which can be represented approximately by the following mathematical equation:

But when one or more of the. foregoing men In the above equation:

A=the per centof apparent copper content A=the percent of actual copper content :r, y, z, etc.=constants for the various added elements m, n, o,etc.=the per cents of the corresponding added elements.

The following elements and their constants are given:

Silicon =9 Lead 0 Aluminum =5 Iron =-0.1 Magnesium=l Manganese =-0.5 Tin Nickel =--.2.2

Cadmium i=0 i To find, for example, the structurally equivalent or apparent copper content of a special brass having an actual copper content of aluminum 2%, tin 1% and balance zincr 100X80 80o0 per cent of appar- A 100 5 X 2 1 X 1 1n ent copper content In other words, the above aluminum brass having an actual copper content of 80% has approxi- -mately the same'degree of saturation of the alpha solidsolution as occurs in straight brass of 72% v actual copper content. Therefore, we may say, that the aluminum brass having an actual copper content of 80% has an apparent copper content of about 72%. ,Generally speaking, the questionas to whether or nota given brass, whether straight or special, will be subject to dezincification, depends upon the structure of the, brass, that is, upon whether its apparent copper content ranges between about 57% and about Sea water and other salt waters, and so-called fresh water such as 'domestic water supplies and allsurface and groundwater supplies, whether of 'shallow 'or deep'origin, all are dezincifying liquids which tend to induce dezincification, and all of them are included by theterm saline liquid. I have found that the addition of antimony to straight or special, normally dezincit lable brasses, distinctly improves the dezincification resistance of the brass. An addition of as little as 0.007 antimony substantially increases tion resistance of brass alloys. The addition of 0.02% antimony to brass alloys further increases the resistance to corrosion and largely changesthe type of corrosion from dezinciflcation to the less harmful general thinning. The addition of 0.09% antimony to. brass alloys still further increases the resistance to dezincification and in the case of some brasses, completely overcomes dezinciflcation, such small corrosion as occurs being general thinning, a comparatively innocuous.

form of corrosion compared to dezlnciflcation, m

the dezincifica- 'to brasses, are 'eflective to improve their dezinciflcation resistance, but when the amount passes above 0.35% antimony, increasing dimculty is encountered in manufacturing wrought-brass tubes, pipes, etc., owing to the inferior working properties of the brasses.

If from %-to 2% of tin is added to brasses containing antimony, the tin aids the antimony in still further improving the dezlnciflcation resistance.

{f arsenic is used in brasses in place of antimony, it improves the dezinciiication' resistance, but tends to bring about a diflerent type of corrosion, namely, intercrystalline attack, which is more severe when small amounts of both arsenic and tin are present.

The addition of small amounts of antimony and arsenic, or antimony, arsenic and tin, greatly improves the dezinciflcation resistance without producing any intercrystalline attacka The following represent some satisfactory dezinciflcation resistant brass alloys having an apparent copper content within a range of from wrought-brass tubes, pipes, etc.:

Acton-loom Aluminum Silicon Tin Nickel Manganese Lead A'ntirnony 4 The following represent" some additional zinciflcation resistant brass alloys: I

g-q snanus:

The invention maybe carried out in other specific ways than those herein set forth without spects as illustrative and not restrictive, and all changes coming within the meaning and equiva- 'lency range of the appended claims are intended to be embraced therein.-

I claim:

1. A dezinciflcation-resistant dezincifying-liquid-contact wrought-brass tube formed from brass containing: an apparent copper content from about 57% to about 85%; an actual zinc content less than the apparent copper content and which if alone with the copper would form a tube which would dezincify; 'an actual tin content from about 54% to about 2%; an actual aluminum content from about t'o'about 4%; and

content less than the apparent copper content and which if alone with the copper would form a tube which would dezincify; an actual aluminum content from about /z% to about 4%; and an actual antimony content small enough to permit the tube to be wrought but sumcient to substantially improve the dezinciilcation resistance of the a tube.

3. A dezinciflcation-resistant dezincifyingliquid-contact wrought-brass tube formed from brass containing: an apparent copper content from about 57% to about 85%; an actual zinc content less than the apparent copper content and which if alone with the copper would form a tube which would dezincify; an actual tin. content from about to about 2%; and an actual antimony content small enough to permit the tube to be wrought but sumcient to substantially improve the dezinciflcation resistance of the tube.

4. A dezinciflcation-resistant dezincifyingliquid-contact wrought-brass tubeformed from bran; containing: an apparent copper content from about 57% to about 85%; an actual zinc antimony content small enough to permit the tube to be wrought but'sufiicient to substantially improve the dezinciflcation resistance of the tube.

5. A dezinciflcation-resistant dezincifyi sliquid-contact wrought-brass'tube formed from brass containing: an apparent copper content from about 57% to about 85%; anactual zinc content less than the apparent copper content and which it alone with the copper would form a tube which would dezincify; an actual tin content from about to about 2%; an actual aluminum content from about A to about 4%; and an actual antimony content from about 0.01% to about 0.85% to substantially improve the dezinciflcation resistance of the tube. v

6. A dezinciflcation-resistant dezincii'ying liquid-contact wrought-brass tube formed from brass containing: an apparent copper content from about 57% to about 85%; an actual zinc content less than the apparent copper content and whichif alone with the copper would form a tube which would dezincify; an actual aluminum content from about 55% to about 4%; and an actual antimony content from about 0.01% to about 0.35%, to substantially improve the def zinciflcationresistanceofthetube. v x 7-. A culmination-resistant deaincifyingaccrual liquid-contact wrought-brass tube formed from ,brass containing: an apparent copper content about 53% to about 85%; an actual zinc content less tl'ian the apparent-copper content and which if alone with the copper would form a tube which would clezincity; anol an actual antimony content from about .lll% to about 0.35% to substantially improve the dezincification resistance of the tube.

9. n oleaincification resistant clezincifying ltnulcbcontact wrought-brass tube formed from brass containing; an apparent copper content from about 57% to about 75%; an actual 'zinc content less than the apparent copper content and which it alone with the copper would form a tube which would clerzincify; an actual tin controzn about to about l%%; an actual ahuninum content from about 1% to about 272%; and; an actual antimony content small enough to permit the tube to be wrought but sumcient to substantially improve the dezincification resistbrass containing: an apparent copper content from about 57% to about 75%; an actualzinc content less than the apparent copper content and which it alone with the copper would form a. tube which would dezincify; an actual aluminum content from about 1% to about il /2%; and an actual antimony content small enough to permit the tube to be wrought but sufllcient to substantially improve the dezincification resistance of the tube. v

11. A dezinciflcation-resistant dezincifyingliquid-contact'wrMght-brass tube formed from brass containing: an apparent copper content from about 57% to about 75%; an actual zinc content less than the apparent copper content and which it alone with the copper would form a tube which would dezincify; an actual tin content from about /g% to about l /z%; and an actual antimony content small enough to permit the tube to be wrought but suiiicient to substantially improve the dezlnclfication resistance of the tube.-

12. A dezlncification-resistant dezinciiyingliquid-contact wrought-brass tube formed from brass containing: an apparent copper content from about 57% to about 75%; an actual zinc content less than the apparent copper content and which it alonewlth the copper would form a tube which would rlezincify; and an actual antimony content small enough to permit the tube to be wrought but sufiicient to substantially improve the dezincificatlon resistance of the tube.

13. A dezlncification-resistant dezinciiyingliquid-contact wrought-brass tube formed from brass containing: an apparent copper content from about 57% to about 75%; an actual zinc content less than the apparent copper content and which it alone with the copper would form a tube which would dezincify; an actual tin con- I tent from about to about 1 /2%; and an actual antimony -contk'sht from about 0.03% to about 0.25% to substantially improve the dezincification resistance of the tube.

14. A dezinciflcation-resistant dezincifyingliquid-contact wrought-brass tube formed from brass containing: an apparent copper content from about 57% to about 75%; an actual zinc content less than the apparent copper content, and which if 'alone with the copper would form to about 0.25% to substantially improve the dezincification resistance of the tube.

15. A' dezincification-resistant dezincifyingliquid-contact wrought-brass tube formed from brass containing: an apparent'copper content from about 57% to about 75%; an actual zinc content less than the apparent copper contentand which if alone with the copper would form a tube which would dezincify; an actual tin content from about /2% to about 1Vz%; an actual aluminum content from about 1% to about 2 and an actual antimony content from about 0.03% to about 0.25% to substantially improve the dez'incification resistance of. the tube;

EDWARD W. ROATH.

7 a tube which would. dezincify; an actual aluminum content from about 1% to about 2 /2%; and an actual antimony content ,from about 0.03%