US2375034A - Apparatus for high temperature tensile testing of materials - Google Patents

Description

M y 1945- M. M. SEMCHYSHEN 2,375,034 APPARATUS FOR HIGH TEMPERATURE TENSILE TESTING 0F MATERIALS Filed Aug. 27, 1945 Patented Ma 1, 1945 T h OFFICE TENSILE TESTING OF MATERIALS Marion M. Semchyshen, Detroit, Mich, to Climax Molybdenum Company, N. Y.; a corporation of Delaware asslgnor New York,

Application August 27, 1943, Serial No; 500,223

' r Claims.

This invention relates to testing of materials and relates more particuiarlyto stress-rupture testing of materials at elevated temperature.

' Objects and advantages or the invention will be set iorth in part hereinafter and in part will be obvious hereirom, or may be learned'by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The inventionconsists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described. J

The accompanying drawing, referred to herein and constituting a part hereof, illustrates one embodiment of the invention, and together with the description, serves to explain the principlesof the invention.

Objects of the invention are: to provide a new and improved testing apparatus; and, to provide apparatus for making stress-rupture tests of materials under a pure tensile load and at elevated temperatures through the use of which" the corrosion variable in tensile testing of materials at such temperaturesis eliminated, or at least reduced to a very small, negligible value. I 0f the drawing: I Figure 1 is a view in front elevationof a typical and illustrative embodiment of this invention; and

Figure 2 is a view taken along Figure 1. In accordance 'with the illustrative-embodithe line 2-2 of ment of the invention, provision is inade for mounting a tensile test specimen between holders in a space which may be evacuated and in which the specimen maybe heated to the desired testing temperature, suitable means being provided length threadedly engage specimen holder 2 l' bers 'ers 2| and 22,

loads of considerable magnitude and as here preferably embodied comprises vertical side rails I; connected at their upper extremities by a horizontal top rail l4 and connected between their upper and lower extremities by a horizontal bottom rail II, the top, bottom and side rails preferablyforming an integral structure. The side rails I 3 are provided between the top and bottom rails I4 and II with a pair of bracket memin opposition the side rails a heater H, to be described more fully hereinafter. I

' Means are provided for supporting a standard tensiletest specimen 20 in the framework In and for applying a load to the test specimen which will produce in it pure tensile stress. The embodied means is readily demountable to permit ready installation and removal of the test specimen and preferably of a nature to permit at least approximate determination of the extent or elongation of the specimen under load. As herepreferably embodied, upper and lower specimen hpldrespectively,

cal contour throughout the major portion of their either end or the test specimen 20 and support it therebetween. A bolt 23 having a bifurcated head portion 24 passes from beneath and through the top rail H in sliding engagement therewith and is threadedly engaged above the rail by an adjustment nut 25 which seats on the rail. The upper end 01' the the bifurcated'head portion 2* to which it is refor externally applying a load of desired magnitude to the specimen in its holders so as to promen from the applied load.

duce and maintain pure tensile stress in the speci It will be understood that the foregoing gen: eral description and the iollowing detailed de-- scrlption as well are exemplary. andexplanatory but are not restrictive of the invention. Referring now more particularly to the accompanying drawing, a framework It preferably of steel is anchored firmly in an upright'position to a suitable base such, for example, as the platform I l to which it is bracedpreierably by" means 01' a pair of rigid brace members l2.

The framework III as embodied is or sturdy construction with a column factor or sufllcientma nitude to preventbuckling under compressive 50, A lever ll positioned between the plate memleasably pin-connected by a pin 26,. In order to prevent rotation of the bolt 23 thenut 25, the top or supporting rail H is provided with a key 21 slidably lodged in a keyway 28 in the bolt shank.

A saddle'iormed by pair or plate members 3! is pin-connected removably to the lower extremity of the specimen holder 22 by a pin 3|, the members 30 being located at either side of the speciment holder and being provided below the pin 3| with an opening '32 in each. The openings 32 are suitably located so as to be coaxial when the members 30 hang vertically and to have their common axis intersect the common longitudinal axis orthe holders 2i and 22 in this condition.

bers 30 is provided intermediate its ends with a pair of knife edges I4 extending in aligned relation from opposite sides of the {lever in the respective openings 82. One end of; the lever exea tends under the bottom rail I} and is provided i I each extending inwardly from its side rail to the other for supporting between preferably of cylindriis lodged between the arms of upon rotation of with a knife edge 35 by which the lever is fulcrumed in a suitably shaped notch 33 in the rail. The other end of the lever is provided with a pivotally mounted weight holder 31 to which weights 33 may be added as required for tensioning th test specimen. Obviously, by varying the weights,

- shown) may be placed in series therewith, so

or if necessary, the length of the lever, any desired tensile stress can be set up in the test specimen.

A bubble gauge 39 is mounted on the lever 33 and enables the operator to tell when .the lever 33 is in a horizontal position which position may be maintained as the load is applied by tighten ing the adjustment nut 25 as required and is the position in which a pure tensile load will be applied to the specimen. The bubble gauge may be suitably calibrated so as to provide means'for measuring the approximate elongation of the specimen when the test is in progress.

In order that stress-duration data of the test specimen may be obtained at high temperature with substantial freedom from the corrosion variable, means are provided for heating the test specimen in vacuo. The heating means as embodied permits maintenance of an extremely rarifled atmosphere around the test specimen in a heated condition and elongation of the specimen at the same time. As here preferably embodied, the upper specimen holder 2| is provided with an annular sealing plate member 40, preferably of steel, concentric therewith and permanently attached thereto as by welding.

A refractory tube 8|, preferably of quartz, coaxial with the seal plate 40 encloses the test specimen 20 and is sealingly connected at its upper. end by an airtight lbellows 42, preferably of metal, e. g. brass or copper, to the seal plate 40.

The lower end of the tube 4| rests upon an annular upstanding flange 43 of an annular member 44 of metal surrounding the holder 22 in spaced relation thereto.

Theannular member 44 is in turn supported by an annular member 45, of metal, permanently attached to and concentric with the lower specimen holder 22. An annular sealing gasket 46 of rubber or other suitable sealing material between the members 44 and 45 together with a series of bolts 4! in a circle concentric therewith provide for sealin the joint between the members 44 and 45. Likewise, an annular gasket 50 43 of rubber or other suitable sealing material snugly encompasses and seals the Joint between the tube 4| and flange 43. In order to avoid destruction of the gasket "by high temperatures, a water cooling coil 43 is wound around this joint so that the gasket may be kept below a temperature of preferably not more than 400-500 F.

Thus. there is provided an airtight expansible chamber for containing the test specimen 20 and from which air is adapted to be evacuated by means ofa pump (not shown) connectable to the chamber by the eduction conduit 50 leading sealingly through the annular member .45.

The heater i1 as embodied is electrically powcred and is suitably constructed to heat the test specimen 20 so that its temperature over its entire length will. be practically uniform. As here preferably embodied, an annular resistance heating element snugly surrounds the refractory m 4| and is jacketed with insulation 52 of required thickness through which pass the power leads 53 to a suitable power source (not shown). The resistance element 5| should preferably be provided with one or more shunts for temperature that the current may be adjusted to a value slightly above that required to maintain the furnace at the desired temperature.

A thermocouple head 54 is placed in the resistance element 5| close to its winding and may.

45 to suitable temperature indicators (not shown).

The instant embodiment is primarily suited to conducting stress-rupture tests up to 1600 F. At higher temperatures, it may be found desirable to place the heater in thespace which is evacuated and seal the whole system with a metallic box.

In order to install the test specimen, the pin 3| may be removed to free the loading apparatus and the bolts 41 removed to free-the lower holder 22. The test piece is then screwed firmly into the upper holder 2|, the lower holder screwed onto the test piece and the bolts and loading apparatus replaced.

The test piece is brought up to temperature in vacuo and the load applied as desired by addition of the weights 38. By maintaining the lever 33 horizontal by means of the adjusting screw 25 the applied load will be. purely tensile. The amount of elongation may be determined approximately by the bubble gauge 39.

The invention in its broader aspects is not limited to thespecific mechanisms shown and-described but departures may be inade therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages. I

What is claimed is: I

1. Apparatus for high temperature tensile testing of materals in vacuo comprising in combination a pair 0 specimen holders for holding a test specimen therebetween; means forming an airtight evacuable, expensible chamber inclosing the test specimen; means for applying a pure tensile load through said holders to the test specimen; and, means for heating the test specimen in vacuo in said chamber.

2. Apparatus for high temperature tensile testing of materials in vacuo comprising in combination a pair of specimen holders for holding a test specimen therebetween; means for supporting one.

of said holders; means for applying a tensile load through the other of said holders to the test specimen; means forming an airtight evacuable, expansible chamber enclosing the test specimen; and, a heater surrounding the chamber. 7

3. Apparatus for high temperature tensile testins of materials in vacuo comprising av pair of specimenholders for holding a tensile test spectmen ther'ebetween; a framework adjustably supporting one of said holders for axial movement; a lever for applying a tensile load through the other of said holders to said test specimen; means forming an airtightevacuable, expansible chamber for enclosing the test specimen; and, an electrical resistance heater surrounding the chamber.

control and if desired an external resistance (not means pin-connected to said upper specimen said holders;

I said holders.

ing oi" materials a,s7c,os4 holder and supporting the same from said frame work for. axial movement; a lever fulcrumed on said framework and pin-connected to 'said lower holder for applying a pure tensile load through said lower holder to said test specimen; a bubble gauge on said lever for indicating the horizontal position of said lever; means including a tube of refractory material and sealing means between ment of one oi said holders,

the same and the holders forming an airtight I evacuable expansion chamber enclosing the test specimen; and, an electrical resistance heater surrounding said tube for heating the test 'specimen. Y

5. Apparatus for tensile testing of materials comprising incombination upper and lower specimen holders tor holding a test specimen therebetween; a, framework; adjustable-means pin connected to said upper specimen holder and supn 1 porting the same for axial movement; means for applying a pure tensile load through 'said lower holder to the test specimen including means forming a thrust bearing pin-connected to said lower specimen holder and a second class lever I having knife-edge bearing engagement with said thrust-bearing means; means for forming an airtight evacuable, expansible chamber for inclosing the test specimen; means for heating said chamlar; and. means responsive to movement of said lever means iorindicatlng the horizontal position of said lever. I

a 6. Apparatus for tensile testing of materials at elevated temperatures in vacuo comprising in combination upper and lower specimen holders for holding atest specimen therebetween; means for applying a tensile load through said holders to the test specimen; a quartz tube surrounding a sealing flange carried by the upper holder, an expansion member connecting said flange with said tube: a sealing flange carried I by the lower holder for supporting said tube;

means for sealing the Joint between said lower holder sealing flange and said .tube; means for cooling said sealing means;-and, an electrical resistance heater in annularly spaced relation to high temperature tensile test- I in vacuo. comprising a pair of specimen holders for holding'a tensile test speci- 7. Apparatus for men therebetween; means for applying a pure tensile load to the pec,

en through said holders; and, means "iorheating the specimen in vacuo comprising generally tubular axially extensiblev chamber-forming and means flexibly con necting said holders and the chamber forming means and providing an evacuabie chamber. for containing the. I resistance heater surrounding said chamber tormingmeans.

specimen;

8. Apparatus for tensile testing of materials comprising axially aligned specimen holders in relatively axially movable relation; a framework; means for effecting non-rotational axial movesaid means comprising a threaded bolt having its head portion pinconnected to said holder and its shank portion slidably socketed in and keyed against rotation in said framework and a nut on said bolt seating on said framework; a tube for inclosing the test specimen and forming a chamber, expansible sealing means between one end of the tube and the first-named holder; sealing means between the other endoi' the tube and the other of said holders; means for heating the chamber and, means including a lever coacting with said framework'for applying a pure tensile load through the other of said holders to a test specimen carried by said holders.

9. Apparatus for tensile testing of materials comprising a pair of specimen holders for holding a tensile test specimen therebetween; means for anchoring one of said holders against axial movement; a tube for inclosing the test specimen and forming a chamber; expansible sealing means between one end of the tube and the first-named holder; sealing means between the other end of the tube and the other of said holders; means for heating the chamber; and, means for applying a tensile load to the other of said holders, said applying means comprising apertured thrust hearing means flexibly-connected t5 said other holder. a second class lever having oppositely extending knife-edge members seated in said apertures of said bearing means; and a gauge on said lever for indicating the horizontal position 01' said lever.

10K Apparatus for high temperature tensile testing of materials in vacuo comprising in combination upper holding a test specimen therebetween; an electrical resistance heater in annularly' spaced relation to said holders for radiantly'heating the test a quartz tube situated between said holders and heater and surrounding said holders;

" a gas-tight bellows connection between said tube and the upper holder;

comprising a sealing flange carried by the lower holder, a tube sealing flange flange and having an bolted to said holder sealing upstanding annular rim seated, agasket sealing upon which said tube is tween said tube and said rim; a cooling coil surtestspecimen and an electrical men between said holde for applying a purely tensile load to a test speci- Memoir M. smrcrrrsm.

and lower specimen holders for v I the joint between said -flanges; and a gasket for sealing the Joint be-

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