U N I T F O R I N V E S T I G A T I N G D E F O R M A T I O N OF

M A T E R I A L S BY T E N S I O N AT D I F F E R E N T T E M P E R A T U R E S

E . A . S u k h o d o l ' s k a y a , B . P . T a r a n , a n d M. S . B r e s l e r

UDC 620.172.087:620.172.251

Prac t i ca l experience in the use of modern power equipment and Diesel engines shows that in a number of cases the choice of construct ional mater ia l s on the basis of the proper t ies determined by standard test methods is insufficient for determining the rel iabil i ty of parts under conditions of complex thermal and mechanical loads. Therefore , in studying the physical nature of mechanical proper t ies and also the mechanism of deformation and failure of mate r ia l s under thermal cycling conditions, muchattention is being devoted to such fundamental cha rac te r i s t i c s as the work for deformation and the coefficient of deformation strengthening [1].

These charac te r i s t i c s may be determined only with the actual cur ren t values of s t r e s ses and deforma- tions. However, for mater ia ls with low ductility the obtaining of the actual cur ren t values of deformation on normal tensile machines is impossible. As a resu l t we have created a special unit for investigating the defor- mation of mate r ia l s by tension over a wide range of t empera tures in vacuum or in an inert gas medium.

The unit consists of a high tempera ture tensile machine and a sys tem for measur ing, recording, and treat ing the resu l t s .

A somewhaL modified IMASh-5S-65 machine was used as the high temperature tensile machine.

The nonautomatic ISD-3 inst rument was replaced with a specially developed inst rument for automatically record ing the curve with increased accuracy , the design of the clamps was changed, and a round sample was used instead of a flat one. The gauge length of the sample was made according to All-Union State Standard 1497-- 61, type 3, 18K and an M8 • 1.5 th readwas machined over the whole length of its heads. However, the use of other types of samples , including flat ones, is possible.

The measur ing sys tem of the unit (Fig. 1) consis ts of three basic blocks: a) measurement of the load; b) measu remen t of deformation; c) t rea tment of the measurement resu l t s .

The load measur ing block includes the s t ra in gauge beam 1, the s t ra in gauge amplif ier 10, and the type GIB1 compensation r e c o r d e r 12.

The deformation measur ing block consis ts of the type 6MKh5S mechanotron 9, the mechanotron power source 11, and the type GIB1 compensat ion r e c o r d e r 14.

The block for t rea tment of the resul ts consis ts of the type MN-7 analog computer 16, the type VI~S-1 stabil ized rec t i f ie r 13, the type PDS-025 two-coordinate recording potent iometer 15, and the oscil lograph indicator 17.

Fig. 1. Schematic of the unit.

Kharkov. Trans la ted from Problemy Prochnost i , No. 9, pp. 121-122, September, 1977. Original ar t ic le submitted October 10, 1976.

This material is protected by copyright registered in the name o f Plenum Publishing Corporation, 227 West 17th Street, New York, N.Y. 10011. No part I o f this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or bv any means, electronic, r:leehanical, photocopying, I

I microfilming, recording or otherwise, without written permission o f tile publisher. A cop)' o f this article is available from the publisher for $ Z 50. 1

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~ , ' + t i ~ V stab. ,~OV~

6.3 V stab.

F i g . 2 F i g . 3

F i g . 2. P l a n of the connec t i on of the 6MKh5S m e c h a n o t r o n .

F i g . 3. P l a n of the c o m p u t i n g b l o c k .

MB2 ~'~ dOIdt

The load m e a s u r i n g b l o c k o p e r a t e s a c c o r d i n g to the n o r m a l m e t h o d . T h e d e f o r m a t i o n s a r e m e a s u r e d in the fo l lowing m a n n e r . A 6MKh5S m e c h a n o t r o n [2] is u s e d as the s e n s o r . T h e b r a c k e t 2 wi th the m e c h a n o t r o n 9 r i g i d l y f a s t e n e d on i t is l o c a t e d on one of the h e a d s of the s a m p l e 5 and the s t r i p 8 wi th the s c r e w - t y p e s t op 7 is l o c a t e d on i t s o t h e r h e a d . Wi th the he lp of the s top the pin 6 of the m e c h a n o t r o n is p l a c e d in i t s o r i g i n a l pos i t ion .

Wi th a change in the s a m p l e length u n d e r the a c t i o n of the load the s t r i p 8 with the s c r e w - t y p e s t op 7 m o v e s r e l a t i v e to the b r a c k e t 2 and the pin of the m e c h a n o t r o n 6 d e f l e c t s in the s a m e d i r e c t i o n by the c o r r e s - pond ing angle with the he lp of the s l i d i n g s top 4 u n d e r the a c t i o n of the s p r i n g 3. T h i s l e a d s to the o c c u r r e n c e in the d i a g o n a l of the b r i d g e of a c u r r e n t the s i gn and a m o u n t of which a r e p r o p o r t i o n a l to the d i r e c t i o n and angle of dev i a t i on of the m e c h a n o t r o n p in . L i n e a r i t y in the r e a d i n g s is p r o v i d e d by the cho ice of the r e s i s - t a n c e s R 3 and R 4 ( F i g . 2) and a l s o by the i n i t i a l va lue of the r e s i s t a n c e s R 1 and R 2.

In p o s i t i o n 2 the toggle sw i t ch T1 c o n n e c t s the two c a l i b r a t e d r e s i s t a n c e s R 6 and R~ to the b r i d g e t o g e t h e r wi th the m e c h a n o t r o n and if the c u r r e n t in the d i agona l of the b r i d g e i s not equa l to z e r o then i t is b a l a n c e d with the he lp of the r e s i s t a n c e R 6.

The m e a s u r i n g l i m i t s a r e changed by the input d i v i d e r of the GIB1 r e c o r d e r .

To r e d u c e d r i f t and i n c r e a s e m e a s u r i n g a c c u r a c y the f i l a m e n t of the m e c h a n o t r o n is p o w e r e d with a s t a b i l i z e d 6 . 3 - V v o l t a g e .

The f ina l p u r p o s e of the t e s t s is d e t e r m i n i n g the a b s o l u t e va lue of the w o r k with any d e g r e e of d e f o r m a - t ion a l l the way to f a i l u r e and a l s o the c u r r e n t a c t u a l va lue of the c o e f f i c i e n t of d e f o r m a t i o n s t r e n g t h e n i n g .

To i n c r e a s e the a c c u r a c y and r e d u c e the w o r k fo r t r e a t i n g the i n t e r m e d i a t e v a l u e s the un i t u s e s a c o m - pu t ing b lock which u s e s an MN-7 s i m u l a t i n g uni t as a b a s e .

I t is known tha t the w o r k of d e f o r m a t i o n s is equa l to the a r e a of the d e f o r m a t i o n c u r v e to a vs e c o o r d i - n a t e s :

A = i (~de, (1) 0

and the c o e f f i c i e n t of d e f o r m a t i o n s t r e n g t h e n i n g is p r e s e n t e d in the f o r m of the r e l a t i o n s h i p

drr e = --~-. (2)

S ince the MN-7 uni t i n t e g r a t e s fo r t i m e , hav ing p r e s e n t e d the va lue s of a and e in the f o r m of func t ions of t i m e , we t r a n s f o r m Eq . (1) in the fo l lowing m a n n e r :

e e d8 t

o G o (3)

To c a l c u l a t e the c u r r e n t a c t u a l va lue of the c o e f f i c i e n t of d e f o r m a t i o n s t r e n g t h e n i n g Eq . (2) is c o n v e r t e d to the f o r m

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to:

d(r 1 o = - ~ . d t - ~ .

The functional c i rcu i t of the computing block is shown in Fig. 3.

1) increase the measur ing accuracy;

2) r eco rd the curves to the coordinates

dff - - t" P - - t , e - - t , (r--e, A - - t , - ~ ,

(4)

The use of this unit makes it possible

3) automate and increase the accuracy in t reat ing the measurement resu l t s .

The unit has been used to determine the work for deformation for a number of alloys in the 20-900~ range. In o rder to protect the mechanotron f rom direct radiation at tes t tempera tures over 450~ it is neces - sa ry to install a special screen .

It should be mentioned that the operat ing principle of the unit and the measur ing c i rcui t are applicable to other tensile machines with an insignificant change in the device for fastening the mechanotron. If it is neces sa ry to subsequently t reat the data on a computer in parallel with any of the indicators used an analog- code conver te r (a digital vol tmeter , for example) may be connected with subsequent delivery of the informa- tion to a pr inter , a perfora tor , or direct ly to the memory of the machine.

1 .

2.

L I T E R A T U R E C I T E D

Ya. 13. Fr idman, The Mechanical P roper t i e s of Metals [in Russian], Mashinostroenie, Moscow (1974). G. S. 13erlin and S. A. Rozentul, Mechanotron Transduce r s andThe i rUse [in Russian], l~nergiya, Moscow (1974).

M E T H O D OF I N V E S T I G A T I N G T H E S U P P O R T I N G

C A P A C I T Y O F M A T E R I A L S W I T H P R O T E C T I V E C O A T I N G S

B . A . L y a s h e n k o , V . V . R t s h i n , V . M. T o v t , l~. S . U m a n s k i i , a n d O. V . T s y g u l e v

UDC 620.05.052

P re sen t service conditions for equipment for new technology are charac te r ized by the simultaneous actio: of high tempera tures , aggress ive media, andmechanica l loads . Investigating the effectiveness of mater ia ls used for the production of this equipment on the basis of the individual action of the service factors does not provide rel iabil i ty in the charac te r i s t i cs obtained because of the nonaddittve nature of the effect of each of them.

in the Institute of Problems of Strength of the Academy of Sciences of the Ukrainian SSR we have devel- oped a combination of methods and introduced experimental equipment making it possible to study the suppor- ting capacity and design strength of base-coat ing sys tems under conditions close to the actual, with the s imul- taneous action of high tempera tures , agress ive media, and mechanical loads.

1. The basis of the methods developed for high tempera ture tensile, creep, and long- term strength tests is radiation heating of the samples , which provides rapid delivery of energy, low inertia, and high clean- liness and cor rec tness in conducting the exper iment [1, 2].

Institute of Strength Problems, Academy of Sciences of the UkraInian SSR, Kiev. Trans la ted f rom Problemy Prochnost i , No. 9, pp. 123-125, September, 1977. Original ar t icle submitted April 8, 1977.

This material is protected by copyright registered in the name of Plenum Publishing Corporation, 227 West 17th Street, New York, N.Y. 10011. No part [ of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, I microfilming, recording or otherwise, without written permission o f the publisher. A copy of this article is available from the publisher for $ ZSO. ]

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