CA1123098A - Method and device for discriminating thermal effect or phase transformation of metals and alloys in the process of their cooling - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A method and apparatus for discriminating the thermal effect of phase transformation of metals and alloys in the process of their cooling, by measuring the temperature of a metal or alloy being cooled, the time elapsed from the beginning of the temperature measuring cycle and the duration of a temperature arrest occuring in the process of the metal or alloy cooling.
The measured duration of the temperature arrest is compared with a threshold of the temperature arrest duration for making a decision ascertaining the occurrence of the thermal effect of phase transformation if the measured duration of the tem-perature arrest exceeds the threshold of duration of the tem-perature arrest. The method further includes measuring an increment of temperature of a metal or alloy being cooled re-lative to the maximum temperature recorded during the tempera-ture measuring cycle, calculating a threshold of duration of the temperature arrest as a function of temperature of the metal or alloy being cooled, and measuring increments of these tem-peratures relative to the maximum temperature recorded during the temperature measuring cycle. The time elapsed from the beginning of the temperature measuring cycle is metered with the threshold value of the temperature arrest duration cal-culated for the moment of occurrence of temperature arrest, being used for the comparison.

Description

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Field of the Invention The present invention relates to physicochemical research in metals and alloys in the metallurgy and, in particular, to methods and devices for discriminating the thermal effect of phase transformation of metals and alloys in the process of their cooling.
This invention can be employed in thermographic analysis of phase transforma-tion of metals and alloys for determining -the temperature of phase transformation. In addition, the present invention can also be used for deter-mining other parameters of metals and alloys, associated with the temperature of phase transformation, and in particular, for determining the carbon content in a molten steel in the process of its produc-tion by the temperature at the beginning of the crystallization (liquidus temperature).
Description of the Prior Art In -thermographic analysis of metals and alloys -there arises a problem of discriminating the thermal e~fect of phase transformation with reference to temperature arrests in the process of cooling of metals and alloys. The diffi-culties in solving this problem lie in that, in practice, apart from the temperature arrests caused by the thermal effect of phase transformation, there also occur temperature arrests as a result of accidental disturbances such as, for example, sharp changes in the heat exchange conditions, i.e.
so~called pseudothermal effects.
In this connection, it becomes necessary to discriminate the thermal effect of phase -transformation in -the presence of pseudothermal effects. The reliability of discriminating the thermal effect can be defined as the probàbility of making a false decision, by the false decision being irnplied both ascertaining the occurrence of the thermal effect of phase transformation on the basis of temperature arrest caused by the pseudothermal effect and ascertaining the absence of the thermal effect of phase transformation on the basis of a tem- -perature arrest caused by the true thermal effect of phase transformation.
A method of discriminating the thermal effec-t of phase transformation of metals and alloys in the process of their cooling is known in the prior art, employing a device for determining the carbon content in a molten metal with reference to temperature arrests in cooling curve (SEE GDR Accepted Application No. 120,713, British Patent No. 1,477,564).
. ~he method comprises measuring such parameters as the terr,perature of a metal or alloy being cooled, the time 3~9~3 elapsed since the start of the temperature rneasuring cycle, the duration of a temperature arrest, and comparing the measured duration of the temperature arrest with a predetermined threshold of the duration of the temperature arrest and making decision ascertaining the presence of the thermal effect of phase transformation on the basis of the results of comparison if the measured duration of the temperature arrest exceeds the predetermined threshold of the duration of the temperature arrest.
A device for carrying out the above method comprises a converter for converting temperature into a digital pulse code, - which is fed through its input wlth a signal containing informa-tion on the temperature of a metal or alloy being cooled, a clock pulse generator, a synchronizer for distributing in time code and clock pulses, a reversible counter for generating a temperature parallel code, a threshold coun-ter for determining local increments of the temperature, a time interval counter provided with information output which contains information on the time me-tered from the next successive moment when a local incremen~ of the temperature assumesa predetermined value. A
signal is formed at an overflow output thereof in case the time exceeds a predetermined threshold of the temperature arrest duration. A cycle counter having information output ~ith information on the , ~Z3(:~9~
f time elapsed since the start of the ternperature measuring cycle. A flip-flop is provided for memorizing a signal occurring at the moment of making a decision ascertaining the occurrence of the thermal effect of phase transformation and a register for storing a parallel code of temperature.
The outputs of the converter for converting tempera-ture into a digi-tal pulse code, code pulses corresponding to a positive and a nega-tive increments of temperature and are connected respec-tively to a first and a sècond inputs of the synchronizer, with an output of the clock pulse genera-tor being connected to a third input of the synchronizer. The first output of the synchronizer is adapted to deliver synchronized code pulses corresponding to a positive ~ncrement of temperature, is connected to add inputs of the reversible and threshold counters. The second output of the synchronlzer, for deliver-ing synchronized code pulses corresponding to a negative increment of temperature and is connected to the subtract inputs of the reversible and threshold counters. ~n output of the synchronized clock pulses of the synchronizer is connected to the count inputs of the time interval counter and the cycle counter.
The overflo~l OUtplltS of the threshold counter, have pulses formed at the moment when a predetermined local increment of temperature occurs and are connected to initial r ~ ~Z3~9~3 setting inputs of the time interval counter An overflo, output of said time interval counter is connected to the control input of the register and to a setting input of the flip~f]op. An information input of said register is connected to an information output of the reversible counter. An output of the flip-flop is electrically coupled with count blocking inputs of the threshold counter and of the tirne interval counter.
During rnetal or alloy cooling, the..code pulses from outputs of the converter for converting temperature into a diyi-tal pulse code, after having been synchronized with the clock pulses in said synchronizer, are fed depending on the sign of the temperature increment, either to the subtract inputs or to the add inputs of the reversible and threshold counters, respectively. As a result, the reversible counter genera-tes a parallel code of temperature and at the overflow outputs of ` the threshold counter pulses a-t the instant of time when a ' local increment of temperature assumes a predetermined value + ~O. These pulses are applied to the initial setting inputs of the time interval counter which counts synchronized clock pulses arriving at its count input. The time interval counter is constructed so that at its overflow output, a pulse is ~; formed in case -the time interval between two successive moments of t~e pulse ,, ~

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arrival at its inputs of initial setting, exceeds a predeter-mined threshold ~O of the ternperature arres-t duration. Thus, -prior to an occurrence of the temperature stop, no pulse is formed at the overflow output of the time interval coun-ter.
When a temperature arrest occurs, no pulses are formed at the overflow outputs of the threshold counter, because the local increment of temperature does not exceed + Eo value. If the temperature arrest duration is in excess of the prede-ter-mined threshold ~O of the ternperature arrèst duration, the time interval counter will overflow, a pulse from the overflow output of said counter will be fed to the control input of the register. In this case, the la-tter is supplied with a code of the liquidus -temperature delivered from the reversible counter. At the moment of making a decision ascertaining the occurrence of the thermal effect of phase transformation, the siynal arriving Erom the flip-flop output will block bo-th the threshold counter and the counter of time intervals. As the predetermined tlrne from the beginning of the temperature measuring cycle elapses, there is a signal at the information output of the cycle counter indicative of the termination of the temperature measuring cycle.
Thus, making a decision ascertaining the occurrence of the thermal effect of phase transformation with the

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use of the above method hnd device. This is done by cornpariny a measured duration ~ of the temperature arrest with the predetermined threshold ~O of the temperature arrest duration.
In practice, there are cases when a temperature arrest caused by the thermal effect of phase transformation is of the same duration as the ternperature arrest caused by the pseudothermal ef.Eect.
In these cases, it is known in the art to not allow such temperature arrest to be distinguished from each other.
Thus, this method does not provide for a sufficient reliability in discriminating the thermal effect of phase transformation.
The principal object of this invention is to provide a rnethod for discriminating the thermal effect of phase trans-formation of metals and alloys in the process of their cooling which, by using additional information on the parameters of metal cooling, improves -the reliability in discriminating such effect.
Another object of the invention is to provide on the basis of simple units used in a digital computing technique employing a device for determining the thermal effect of phase transforma~ion of me-ta]s and alloys in -the process of their cooling wilich employs additional information on the parameters of cooling, and can improve the reliability in discriminating the effect.

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These and other objects of the invention are attained by the proposed method and apparatus for discLiminating the thermal effect of phase transformation of metals and alloys in the process of their cooling, by measuring the temperature of a metal or alloy being cooled, the time elapsed from the beginning of the -tempera-ture measuring cycle, and the duration of a temperature arrest occurring in the process of the metal or alloy cooling. The measured duration of the temperature arrest is compared with a threshold oE the ter~perature 10 arrest duration for making a decision ascer-taining the occurrence of -the thermal effect of phase transformation if the measured duration of -the temperature arrest exceeds the threshold of duration of the temperature arrest. The method further includes measuring an increment of -temperature of a metal or al:loy being cooled relative to the maximum temperature recorded during the temperature measuring cycle, calculating a threshold of duration of -the temperature arrest as a function of tempreature of the metal or alloy being cooled, and measur-ing increments of these temperatures relative to the maximum temperature recorded during the temperature measuring cycle, and metering the time elapsed from -the beginning of the temperature measuring cycle is metered wlth the threshold value of the temperature arrest duration calculated for the mornent of occurrence of ternperature arLest, being used for the comparison.

Z3~g8 ~ 'hese and other objects of the invention are a1SG
attained in a ~evice for car~ying out the above method~
comprising a converter9 for converting temperature into a di~ital pulse code, which is fed through its i~ut with a sig~al containin~ information on ~he temperature of me~al or alloy bei~g cooled, a sy~chronization unit for distri-buting i~ time code and clock pulses~ having inputs con-~ected to outputs o~ said co~erter, at which outputs there appear code pulses corresponding to positive a~d ne-gative incremen~s o~ temperature, and to an output o~ a clock pulse generator, a reversibla counter, for genera-ting a parallel code corre~po~di~g to a measured tempera-ture 7 having its add and subtract inputs conn~cted to outputs of the synchronization unit, at which out~uts therP
appear s~nc~ronized pulses correspo~ding ~o positive and .
~egative increments o~ temperature, a t~reshold cou~ter ~or determini~g temperature local increments, havi~g add a~d subtxact inputs co~ected to said outputs o~ the syn;~
chronizatio~ unit~ and to a cou~t blocking input o~ which is applied a signal at a mome~t whe~ the theI~al effect of the phaæe transformation is ascertai~ed, whereas at its fir~t and seco~d over~low outputs there are formed iulses : at moments when local positive or negative tempeIature increments assu~e a predetermined valuel a cou~ter o~ time intervals m~tered starti~g ~rom a ~oment when a local tem-' `

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perature increment assumes a predetermined value, the counter having a count input connected to a synchronized clock pulse output of the synchronization unit, and initial setting inputs connected to overflow outputs of the threshold counter. To the count blocking input of the time in-terval counter there is applied a signal at a moment when the thermal effect of the phase transforma-tion is ascertained, and a main register, for storing a parallel code of metal or alloy temperature, has an information input connected to an informa-tion output of the reversible counter. A main control input has a signal applied to control entering information into said main register, a cycle counter, for metering the time elapsed since the start of the temperature measuring cycle, has a count input connected to the synchronized clock pulse output of the synchronization unit, and an information output whereat there appears information on the time elapsed since the start of the temperature measuring cycle. The proposed device further includes aacording to -the invention, an additional register for storing a parallel code of a time interval elapsed from the start of the temperature measuring cycle to the next successive mornent when the local increment of temperature assumes a predetermined value, having an inforrnation input connected to the information output of the cycle counter, and control inpu-ts connected to overflow outputs of the threshold counter, a tempera-ture incre-~3~

ment counter for deter~iningg a temperatu~e increme~ rela- -tive to the maxim~m temperature recorded during the terr-perature mea~uring c~cle~ having a count input connected to the ~eco~d o~er~low output of said threshold counter~ a salector of sig~s o~ the thermal e~ect o~ ~hase tran~Lor-mation~ having inputs connected to the information outpu~s of the main regist~r~ o~ the temperature increraent counter of the aGditio~al register, and of the time interval counter~
and an output connectod to the count blocking inputs o~ the threshold counter and o~ the time i~terval counter~ with the main and the additional control inputs o~ said main register~ being con~ected to the over~low outputs of said threshold cou~ter~
The use of additional information o~ the parameters o~ the process of cooling o~ metals a~d alloys by the above method and device9 in acGordance with the invention9 allowæ the reliability o~ determining the thermal e~ect o~ phase transfo~mation to be improved.
~ hese and other objects a~d advantageæ of the invention will now be explained in greater detail with reference to ..
embodime~t~ thereo~ which are represented i~ the accompanying ; drawi~gs, ~herein:
~, ~ig~ 1 is a typical cooling curve o~ a metal or an allog, illustra~ing a method i~ accordance with the inven-tion;

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~ig, 2 i~ substan~ially similar to tha~ of ~
~igo ~ is subs~ntially similar to that of ~ig~ 1;
~ig~ 4 is substantially similar to that of ~ig. 1g - Fig. 5 is substantially similar to tkat of ~ig. 1;
~ i~. 6 is a block diagram of the device for aiscrimi-nati~g th~ ~hermal effect of phase trans~ormatio~ of met~ls and alloys~ according to the i~ventio~;
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~ ig. 7 is the cooling curve illustrating the operatio~
of the device for discriminating the the~mal effect of phase trans~ormation o~ metal~ a~d alloys, according to the nventlon;
~ ig. 8 is a fu~ctional diagram of a converter for-co~-verting temperature in~o a digital pulse code, according to the inveutio~;
~ ig. ,a7 b7 C7 dg e7 ~7 g, h3 ig a are the time plots illustrating the operation of the converter of temperature into a digital pulse code with a positive increme~t of tem-perature, according to the invention;
Fig. 10 is ~ubsta~tially similar to that of ~ig. 5 but with a negative i~crement of temperature9 ~ ig. 11 is a ~u~ctional diagram of a synchronization ni~according ~o the invention;
A ~ig~ ~2ag b, c, dl e; ~, g,~l, j, k are time plots illustrating the operatio~ of a synchro~ization unitg accor-ding to the inve~tion;

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3~9~ -Fig. 13 is a functional diagram of a selector of si~ns of the thermal effect of phase transformation, accordiny to the invention.
A method of discriminating the thermal effect of phase transformation of me-tals and alloys in the process of their cooling will further be illustrated with the aid of a coo].ing curve which represents a graph of -the temperature variation of a metal or alloy being cooled. A representative shape of the cooling curve is illustrated in Figs. 1, 2, 3,

4, 5.
In the process of cooling a sample of the molten metal, there are measured a temperature T of -the metal and time t elapsed since the start of the temperature measuring cycle. In addition, there is measured an increment aT of tempera-ture of the metal being cooled relative to -the maximum temperature TmaX recorded during the temperature measuring cycle. On the basis of the measured parameters taken in the aggregate, a threshold ~O of the -tempreature arrest duration is continuously calcu]ated with the following formula:
~O - F (T, ~T, t) (1) The function F is determined beforehand on the basis of statistical processing of the real cooling curves of metal samp]es, where temperature arrest ..~

~L~LZ3~98 caused by the ~hermal e~fect o~ phase transformation~ and temperature arrest causeà b~ the p~eudothermal ef~ec'c' 'l'~e use Q~ know~ methods o~ the theo~y o~ sta~istical decisions allows this ~unction to be selected such that a probabilit~
o~ ~alse decisio~s is mi~imal~ A fu~ction ~ may b~ given either anal~ticall~ or in the ~orm of a table.
As soon a~ a temperature arrest occurs on the cooling curve9 its duratio~ ~ is measured~ ~he measured duration of the tamperature arrest is compaxed vith a threshold value ~0 o~ the temperature arrest duratio~ calculated ~or the mome~t when the temperatuxe arrest occurs. ~f a duration ~ of the temperature arrest exceeds ~ 0 value7 a decision is made ascextaining the occure~ce o~ the thermal ef`~ect o~ phase trans~oxmation o~ a me~al or alloy beinO
cooledO I~ case~ the duratio~ ~ o~ the temperature arres~
is less than a thxeshold ~0~ a ~ecisio~ is made ascer-tai~ing the absence o~ the the~mal ef~ect o~ phase txa~s-~or~ationg which is i~dicative of that this temperature ar-rest is caused by the pseudothermal ef~ec~.
~ he mcthod will be'des ribed ~æ~æ~ by w~y o~ examples9 in accordance with the i~ve~tio~0 I~ the ~abla below there are gi~en optimal values of a thI~eshold ~0 obtai~ed on the basis o~ statis~ical proces-si~g of cooling curves of molte~ steel samples f~or some ~a-lues ~3 ~ T,- t in compliance with (1) -16~
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~ C ~ C t~ sec O ~o ~ sec.

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1510 ~2 5 3 15~5 12 2 8 ,. .. _ . ... ...
~ elationship give~ i~ the above table is ~ot to be conoidered as the o~ly possible one~
~ample 1 ~ tempexature arrest whose duration ~1 is 4 ~econds is recorded at a temperature T1 (~ig. 1) o~ metal~ which is equal to 1510Co A maximuim temperature T1maX recorded during a temperature measuri~g cycle is 1522C~ i.e.
~ T=12C. ~'ime t1 elapsed $ince the start o~ the temperatu-re measuring c~cle till the mome~t of ~ccurrence o~ a tem-perature ar~est, is 5 seconds. In accordance with the data -- ~7 --, .
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illustrat~Ad in the Ta~le, a ~hreshold value ~o1 Lr the given parame~er~ is 3 seco~dsO Consequently, in this case a decisio~ is made ~3, cc.r-~ai~ the occurence of the thermal e~ect of phase trans~ormationO
Example 2 A temperature arrest whose duration ~ 2 is 4 seconds is recorded at the temperature T2 (Fig. 2) which is equal to 1510Go ~ maximum temperature T2 ma~ recorded duri~g a temperature measurin~ cycle is 1530C~ Time t2 elapsed si~ce the start of'temperature measuring c~cle is 5 secon-ds. In accordance with the data illustrated i~ the Table~
a thxeshold value Lo2 ~or the given parameters~ is 5 se-conds. Con.~eq~entlyg in this case,a decision is made ascertai~ing the absence o~ the thermal e~ect o~ phase tra~s~ormationO With the giva~ values o~ parameters o~ the temperature arrest caused by the thermal e~fect o~ phase trans~ormation o~ly such a temparature arrest will be reco~nized9whose duration exceeds 5 seconds~
Example 3 A temperature arrest with a duration r3 of ~ seconds is recorded at a tem~erature T3 (Fig~ 3) which is equal to 1510C~ A maximum temperature T3 max recorded duri~g the temperature measuri~g cycle is 1522C. ~ime t3 ~lapsed since the start o~ the temperature measuri~g cycle is 12 se-cond~ accorda~ce with the data illustrated i~ the Table : . .
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l~Z313~8 a threshold value ~0~ ~or the given parameters is 6 se-conds~ Consequen~ly~ in this case a decision is made ascertainin~ the absence o~ ~he ther~al e~ect of phase transformatio~4 ~xample 4 A temperature arrest with a duration ~4 of 4 seco-~ds is recorded at a temperatuLe ~4 (~ig. 4) which is equal to 1525Co A ma~imum temperature ~4 ma~ recorded durin~
: the temperature measuri~g cycle is 15~7C. Time t4 elapsed si~ce the start of' the temperature measuring cycle is

5 seconds. In accordance ~ith the data illus~rated in the Table a threshold value ~0~ for the given parameters is

6 seco~ds. Con~e~uently~ i~ this caseJa decision is made indicative o~ ~hat there is no thermal effect o~ phase transformation.
~xample 5 A temperature arrest with a duratio~ ~5 o~ 12 secondæ
is recorded at a temperature ~5 (~ig~ 5) which i5 equal ~o 1525C. A ma2imum temperature ~5maæ recorded duri~g ~he temperature mea~urî~ cycl~ is 1537C. Time t5 elapsed since the ~tar-~ o~ the temperature méasuring cycle is 12 se- -; co~ds. In accordance wi~h the dat~ illustrated in the '~able a threshold ~alue ~05 for the gi~en parameters seconds~ Co~equ~ntl~ this caso,a decision is mada as certaining the .occurence of the ther~al e~ect o~
; phase tra~sformatio~

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~Z3~98 ~ device for discriminati~ t~e thermal e~fect of phase trans~ormation OL metals and allo~s in the proccss of t~eir cooling9 employing the above method, co~prises a converter 1 for converting -~emperature into a di~ital pulse code (~i~. 6)~ a clock pulse generator 2~ a syncnro-nizatio~ unit 3~ a reversi~le counter 4, ~ main register 5 a ~hrashold counter 69 a cycle counter 77 an ad~ition~l register 8, a time interval cou~ter 97 a temperature iLC-rement counter 10, and a selector 11 o~ signs o~ a -the~nal e~Lect o~ phase transformatio~0 An input 12 oi the conver-ter 1 is connected to a tempera~ure ~ensor~ for instance, to a thermocouple (not shown)0 Outputs 13~ 14 OL the conver-ter 1 are connected to a firs-t and a second inputs of the synchronization unit 3, respectively, whose third input is connected to an output 15 o~ the clock pulse generator 2.
A synchro~ized clock p~lses output 16 o~ the s~nchro~iza-tion unit 3 is connected to count inputs o~ the cycle coun-ter 7 and o~ the time i~terval cou~ter 9~ an output 17 o~
the sync~ronization unit 3 is connected to add i~puts 01 the threshold counter 6 and of t~e reve~sible cou~ter 4, with an output 18 O1 the synchronization u~it ~ being con-nected to subtract input~ o~ the threshold counter 6 and of the reversible counter 4. An infoImatio~ output 19 of the reversible counter 4 is con~ected to an in~or~atio~ in-put of ~he main registex 59 O~erflow ou~puts 20, 21 of the threshold counter 6 are connected to control i~puts of the ..

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main and o~ the auxiliary registers 5, 8 and to initial settin~ inputs o~ the time inter~al counter ~0 An over-flow output 21 o~ the threshold counter 6 is con~ected to an input o~ the tem~erature increment cou~ter 10. An information ou~put 22 o~ the c~cle counter 7 is con~ected to an information input of t,he additional re~ister 8. An in~o~mation output 23 o~ the auxiliary register 8, a~ in-~ormation output 24 of the time interval counter 9~ an i~-formation output 25 OL the temperature i~crem~t cou~er 10 and a~ inLormation output 26 of the main register are connected to inpu~s of the selector 11 of sig~s of the ther-mal effect o~ phase transformation. ~ output 2'7 of the sele- -ctor 11 o~ signs of the thermal effect o~ pn~se ~ransforma-tion is co~ected to cou~t blocking i~puts of the time interval cou~ter 9 and o~ the threshold counter 6, ~ ig. 7 shows a cooli~ curve illustrating the operation o~ the proposed device.
Fig. 8 shows a modilication o~ the converter ~or con-verting an analo~ue signal i~to a digital pulse cod~, whe-rei~ an analogue signal is a signal containi~g i~for~ation on the temperature o~ a metal being cool~d~ I~ this case a~ i~put 12 (~ig. 6) may be mechanically coupled~ for example, with a slide co~tact of a~ auto~atic potentiometer co~ti~uously ~ed with a signal ~rom a temperature se~sor.
~he conver~er 1 (~ig. 8) includes a measuring scale whe-~ .
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~L~23~8 ~ Ee~ there-~.rc alternate transparent mark~ ~9 and non-i~ -transparent marks 30 of equal widths. A number of the marks determines a resolving power o~ the converter 17 r~ e converter 1 further includes two photodiodes 31~ 32 and a dial lamp ~3 which are ~ou~ted o~ a holder 34, ~he pno~o-diodes 31 and 32 are spaced relative to each other-~-;it~,i~
a dista~ce equal to halL the widths of the marks ~9, 30.
The holder 34 o~ t~e co~verter 1 is mechanicall~
cou~led with the slide con~act ~5 01 the automatic poten-tiometer ~6.
In addition, the oo$verter 1 comprises two Schmitt triggers 37~ 38, two pulse shapers 39~ 40 at a positive front of the signals arriving from outputs Q~ the Schmitt tri~-ger ~8 and two gate~ 4~, 42 for selecting code pulsas corresponding to positive and negative i~creme~ts of tem-perature o~ the cooling curYe~ -~ An input OL the ~chmltt trigger 37 is co~nected to an : output o~ the photodiode 31 whereas an i~pu~ of the Schmitt trigger 38 is connected to a~ output o~ the photodiode ~2.
A æero output o~ the Schmitt triggex ~7 is connected to control inputs o~ the gates 41 a~d 42.
A unity out~ut o~ the Schmitt trigger 38 is co~ected to a~ i~put o~ the pulse shaper 39 whereas the ~.ero output o~ the Sch~itt trigger ~8 is co~ected to a~ in~ut of the pulse shaper 40.

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' :' )98 An output of the pulse shaper 3g is connected to a pulse input of the gate 41 whereas an output of the pulse shaper 40 is connected to a pulse input of the qate 42.
Code pulses of the converter 1 at outputs ofthe gates 41, 42 corresponding to positive and negative increments of temperature on the cooling curve.
This invention may be variously otherwise embodied.
Figs. 9 and 10 illustrate time plots of the opera-tion of the converter 1 with positive and`negative temperature ]0 increments.
Fig. 11 is a preferred embodiment of a synchronization unit 3. The synchronization unit 3 includes an element 43 for ; distributing clock pulse and elements 44 and 45 for synchroni-; zing code pulses. The element 43 for distributing clock pulses comprises a flip-flop 46 for distributing clock pulses, a gate 47 for forming synchronized clock pulses and a gate 48 for forming synchronizing clock pulses. Control inputs of the gates 47 and 48 are connected to outputs of the flip-flop 46. Pulse inputs of the gates 47 and 48 are interconnected and connected to a count input of the flip-flop 46, serving as an input of the synchronization 3, where there are applied pulses from a clock pulse generator 2 (Fig. 6?. An ou-tput of the gate 47 (Fig. 11) is an output 16 (Fig. 6) of synchron-ized clock pulses of -the synchronization unit 3. The elements 44 and 45 for synchronizing .. .

309~ -code pulses comprise flip-flops 49 and 50 for storing the code pulses, huffer flip-flops 51 and 52, AND circuits 53 and 54, gates 55 and 56 for forming synchronized code pulses.
A unit input of the flip-flop 49 is an input of the synchronization unit 3, where code pulses are applied corres-ponding to a positive increment of temperature on the cooling curve.
A unit input of the flip-flop 50 (Fig. 11) is an input of the synchronization unit 3, where code`pulses are applied corresponding to a negative increment of temperature on the cooling curve. Inputs of the AND circuit 53 (Fig. 11) are connected to a unit output of the flip-flop 49 and to a zero output of the flip-flop 51.
Inputs of the AND circuit 54 are connected to a unit output of the flip-flop 50 and to a zero ou-tput of the flip-flop 52. A -third input of each of the AND circuits 53 and 54 is connected to an output of the gate 48 for forming synchro-nizing clock pulses of the distributing element 43. The out-put of the gate 48 is also connected to one input of the gate 55 of the element 44 and to one input of the gate 56 of the ele-ment 45. The other inputs of each of the ga-tes 55 and 56 are connected -to unit outputs of the flip-flops 51 and 52, respec-' tively. An output of the AND circuits 53 is connected to a unit input of the flip-flop 51, . .

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1~23~8 whereas an output of the AND circuit 54 is connected to a unit input of the flip-flop 52. An output of the gate 55 is connected to zero inpu-ts of the flip-flops ~9 and 51, and is an output 17 (Fig. 6) of the synchronizer 3, where -there are applied synchronized code pulses correspQnding to a positive increment of temperature on the cooling curve.
An output of the gate 56 (Fig. 11) is connected to zero inputs oE the triggers 50 and 52, and is an output 18 (Fig. 6) of the synchronizer 3, where there are applied synchronized code pulses corresponding to a negative increment of temperature on the cooling curve.
Shown in Fig. 12 are time plots illus-trating the operation of the synchronization unit 3.
Fig. 13 shows an alternative embodiment of the selector 11 of signs of the thermaleffect of phase trans-formation. The selector comprises a decoder 57 whose inputs ; are the inpu-ts of the selector 11, and "OR" circuit 58 having its inputs connected to the outputs of the decoder. The output of the "OR" circuit 58 is at the same time the output 27 of the selector 11.
The device operates as follows. The signa~ carrying information on the temperature of the metal or alloy being cooled is delivered from the temperature sensor to the input 12 of the converter 1 oE temperature into a digi-tal .

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pulse code. The signal converted into a digital pulse code is fed to the outputs 13 and 14 of the converter, with each elementary incremen-t of temperature there are formed code pulses at one of the outputs 13, 14, depending on the sign of the temperature increment. These code pulses from one of -the outputs 13, 14 are fed to the respective input of the synchronizer 3. C1.ock pulses from the output 15 of the clock pulse generator are also fed to the synchronizer 3. The synchronizer 3 provides for dis-tribution in time of code and clock pulses which is needed to preclude malfunctioning of the device. Synchronized clock pulses arrive at the output 16 of the synchronizer and further at the count inpu-ts of the cycle counter 7 and the time interval counter 9. Synchronized code pulses corresponding to the positive increment of tempera--ture are fed from the output 17 of the synchronizer to the add inputs of the threshold counter 6 and the reversible counter 4.
Synchronized code pulses corresponding to a negative increment of temperature are fed from the output 18 of the synchronizer 3 to the subtract inputs of the threshold counter 6 and the ~ 20 reversible counter 4. In the reversible counter a parallel ; code is formed of the metal current temperature. The threshold counter 6 provides for selection of local increments of temperature and is constructed so that its overflow outputs 20, 21 pulses are formed each time .

35~
when a number of code pulses being fed to its inputs corres-ponds to a certain threshold + ~O, i.e., at the overflo~l outputs 20, 21 of the threshold counter 6 pulses are formed providing there are certain positive or negative temperature incremen-ts of the metal, respectively. These pulses are applied to the initial setting inputs of the -time interval counter 9 and to the control inputs of the main and the additional registers 5, 8. Pulses corresponding to negative increments of temperature are fed from the overflow output 21 --to the count input of the temperature increment counter 10.
Prior to the start of each measuring cycle, the cycle counter

7 is set to its initial state and, consequently, its contents in the process of a metal or an alloy cooling are proportional to the current time elapsed since the start of the temperature measuring cycle. As soon as the successive pulse is fed either from the overflow output 20 or 21 of the threshold counter ~ to the control inputs of the main register 5 and the auxiliary register 8, there is entered a code from the information output 22 of the cycle counter 7 into the main register 5, the code being proportional to the time that -elasped from the beginning of the cooling process till the moment when the threshold counter 6 is triggered. Similarly, from the information output 19 of the reversible counter 4, there is entered a code into the register 5, which is propor-tional to the '', ~ 30 ~f -~1 ~ 3 ~9 ~

temperature o~ the metal at the moment when the threshold counter ~ come~ into action .
A code proportional to the time elapsed ~rom the be-g o~ the measuri~g cycle, is continuously ~ed from the in~ormation outpu~ 23 o~ the auxiliary re~ister 8 to the selector 11 input. A code proportional to the current temperature o~ a metal or an allo~ being cooledg is con-~inuously ~ed from the information output 26 o~ the main register 5 to the other i~put o~ the selector 11.
'~he temperature i~creme~t counter 10 provides for de-termining a temperature i~crement relative to the maximum temperature ~max (Fig. 7) recorded durin~ a temperature measuri~g cycle. Prior to the start of the temperature mea-suri~g cylc1e ~he cou~ter 10 (~ig. 6) is set to the i~itial state. 0~ the portion 0-~ (~ig~ 7) o~ the cooling culve, correspo~di~g to a positive increme~t o~ temperature, pulses are ~ormed only at the out~ut 20 (Fig. 6) o~ the threshold counter 6~ Co~seque~tly, ~o pulses are fed the cou~t i~put o~ tha temperature i~creme~t counter 10 and i~ retains its i~itial state.
On the portion A-B (~ig. 7), corresponding to a nega-tive increment of' temperature~ pulsas are ~ed from the overflow output 21 of the threshold cou~ter 6 to the count i~put o~ the temperature increment cou~ter 10. As a result, ;

.
.

- i . . . . . ..

~230~

o~ ~ o ~
in ~his counter thcre ~ff ~rme~ a code'proportional to a negative tamperature increment o~ the metal or allo~ ~eing cooled, relative to the maximum temperature ~max of the .
cooll~g curve~
~ nfol~atio~ from the informa~ion output 25 of ~he tem-perature increment counter 10 is continuously fed to th~
i~put of the selector 11 of signs of the thermal ef~ec~ o~
phase transformation~
~ he time i~terval coun~er 9 pro~ides for determining the time interval between two successive i~s~an~s of time when a local increme~t of temperature assumes a predeter- -mined value ~O. ~ach pulse which is formed at the overf'low outputs 207 21 of the threshold cou~ter 6 sets the counter 9 to its ini~ial state, whereupo~ the counter 9 starts a ne~v time metering by calcula~ing clock pulses. Information ~rom the information outpùt 24 o~ the counter 5 is con~inu-ously fed to the i~put of the selector 11 o~ slgns of the thermal effect of phase transformatio~.
Thus1 in the process of me~al or alloy cooling the inputs of the selector 11 of sig~s of the thermal effect of phase ~ransformation are co~tinuou~ly supplied with i~for-matio~ on~he temperature ~ of a metal or a~ alloy~ on the i~creme~t of temperature ~ T of a metal or a~ alloy, o~ -the time t elapse'd from the beglnning of the temperature mea-... .

- .
` - 29 _ ~ , ' . .
"~ ' ' ' ' . ' " ` ~
',, ' ~ ~

,~' ' '' .

~ 3098 suring cycle and on a ~alue r~ of the time interval ela~-sed since the successive moment when a~ increment of tem-perature has assumed the predetermined value. 'n this case, the informa~ion on values '~ and t varies only at the O ~ <~ ~,~
~ff~ S whe~ an i~crement of temperature assumes the pre-determined value ~0~
The selector 11 of signs of the thermal e~fect is con-st~ucted so that a control signal is ~ormed at the ou~put 27 only when the time interval ~ determined b~ the time interval ceunter 9 9 iS equal to a threshold rO of the duration of a temperature stop, with said threshold bein~;
dependent o~ parameters '~, ~ l' and t accor~ing to the formula (1).
In the process of metal or alloy cooling,prior to occurrence o~ a temperature arrest (portions O-A and A-~of the cooling curve i~ Fig. 7) 9 the threshold counter 6 will conti~uously reset the time interval counter 9 in its initial state so that the conte~ts o~ the latter does not assume a value equal to a threshold ~0 of the du~ation of the temperature ar~est. Consequently 9 at this stage . . .
; o~ the proces~ of cooling~no control sig~al is ~ormed at the output of the salector 11 of sig~s of the thermal e~fect of phase transformation. I~ in the process o~ cooling there occurs temperature arrest whose positive or negative incre-.
. , , , ~0 --, ~ .

ment of temperature does not exceed ~ , the threshold counter 6 will not be overflown. If duration ~ of the tempera-ture arrest is such that the contents of the time interval counter 9 assumes a value equal to a threshold ~O of the duration of the temperature arrest, determined by parameters T, AT and t calculated for the moment when the -temperature arres-t occurs, at the output 27 of the selector 11 of siyns of the -thermal effect of phase transformation a control signal is formed. This signal is fed to the count blocking inputs ]0 of the threshold counter 6 and the time interval counter 9, whereby excluding a possibility of the information alteration in the counters 9 and 10, and in the registers 5 and 8. As a result, a control signal at the ou-tput 27 of the selector 11 of signs of the -therrnal effect of phase transformation is retained till the successive measuring cycle. The appearance of this control signal is indicative of -the presence of -the therrnal effect of phase transformation. The information stored in the main register 5 after formation of this control signal, repre-sents a code of the liquidus -temperatures of a metal or an alloy. This information can be directly transrnitted to the rnaster computer, to the digital display unit, to the digital printer, e-tc. for represen-tation of parameters of a metal or an alloy, for instance, to indicate the carbon content therein.

~'~
...

~ he ~ ~ iple of the co~verter 1 shol.vn i-~~ig. 8 is illustra~ed by the time plots in ~igs 9, 10.
~ he movement o~ a sliding contact 35 (Fig. 8) of a~ automatic potentiome~er ~6 is parallel to ~hat o~ a holder 34 of the co~verter 10 ~he light ~lux of a dial l~p 33~ incide~t on photodiodes 31 and 3~ is modulated by mar~s 29 a~d 30 of a measuri~g scale ~80 Sig~als from the photodiodes 31 and 32 are applied to the inputs of Schmitt trigger 37 and 38~ respectively.
When ~he slide co~tact 35 i~ movi~g ~rom le~ to right, ~he ~ignal (~ig~ 9a) o~ the pho~odiode 31 (~'ig~ 8) lags b~
a quarter of a period behind the signal (Fig. 9b) of the photodiode 32 (Fig~ 8). I~ this case the sig~al (~ig. 9c) at the unity output a~d the sig~al (~ig. 9d) at the zero output o~ the Schmitt trigger 37 (Fig~ 8) lags by a quarter of a period behind the sig~al (~ig. ge) at the u~ity output and the sig~al (Fig. 9~) at the ~exo outpu~ o~ the Schmitt trigger 38 (~ig~ 8), respectlvel~.
A pulse shape~ 39 ~orms pulses (~ig. 9g) on the positi- ;
ve ~ront side o~ the sig~al- (~igr 9e~ arriving from the u~it~ outpu~ of the Schmitt trigger 38 (~ig~ 8)~ A pulse ~haper 40 f orms pulses (Fig~ 9h) on the positive front ~ide of the signal (~ig. 9f) arrivi~g ~rom the zero output o~ the Schmitt trigger 37 (~ig~ 8)~

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l - ~2 -. , , ~.. . .. . .. . . .
, ~
~. . .
, ~ ' : .:. '` :
- .

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l'he pulses (Fig. gg) are fed to the pulse input of a gate 41 from the output of the signal shaper 39 (Fig. 8). The pulses (Fig. 9h) are fed to the pulse input of the gate 42 from the zero output of the signal shaper 40 (Fig. 8). The signals (Fig. 9d) are fed to the con-trol inputs of the gate 41 and the gate 42 from the zero output of the Schmitt trigger 37 (Fig. 8).
In this case as is seen from the timing chart (Fig. 9), at the moment when signals are applied to the pulse input of the gate 41 (Fig. 8), the gate 41 is locked bècause there is applied an inhibi-tory signal to its control input from the zero output of the Schmitt trigger 37. At moment when signals are applied to the pulse input of the gate 42, the gate 42 is open because there is applied a permitting signal to its control input from the zero output of the Schmitt trigger 37.
At the same time, as the sliding contact 35 (Fig. 8) moves from left to right, no signals (Fig. 9i) are formed at the output of gate 41 (Fig. 8). The signals (Fig. 9j) at the output of the gate 42 (Fig. 8) are code pulses of the converter 1, corresponding to a positive increment of temperature on the cooling curve.
When the s]iding contact 35 (Fig. 8) is movlng from right to left, the signal (Fig. lOa) of the photodiode 31 (Fig. 8) is a quarter of a p~riod ahead of the signal ; ~ .

3~39~
(Fig. lOb) of the photodiode 32 (Fig. 8). In connection with this, at moments when the pulses (Fig. lOy) from the pulse shaper 39 (Fig. 8) are applied to the pulse input of the gate 41, permitting signals (Fig lOd) are fed to the control input of the gate 41 Erom the zero output of the Schmi-tt trigger 37 (Fig. 8). At moments when pulses (Fig. lOh) arrive from the pulse shaper 40 (Fig. 8) to the pulse input of -the gate 42, inhibitory signals (Fig. lOd) are fed to the control input of -the gate 42 from the zero output of the Schmitt trigger 37 (Fig. 8).
At the same time, as the sliding contact 35 (Fig. 8) ; moves from right to left, no signals (Fig. lOj) are formed at the output of the gate 42 (Fig. 8). The signals (Fig. lOi) at the output of the gate 41 (Fig. 8) are code pulses of the ~ converter 1, corresponding to a negative increment of - tempera-ture on the cooling curve.
~ The operating principle of the synchronizer 3 shown .~ , in Fig. 11 is illustrated by the timing char-ts in Fig. 12.
When clock pulses (Fig. 12a) are fed from the generator 2 (Fig. 6) to the count input of the flip-flop 46 (Fig. 11) of the clock pulse distributing element 43, the flip-flop successivel~ changes its state. Signa]s from the unity output (Fig. 12c) and zero output (Fig. 12b) of the flip-flop - 46 (Fig. 11) are applied -to the control inputs of the ,, .

~Z3~g~ -- .
gates 47 and ~89 respectively. The pulse inpu~s o~ thes~ -gates are fed with the clock pulses (~ig, 12a) from the generator 2 (I~'ig. 6). As a result, at the outputs of ~
gates two pulse trains are ~ormed shifted in time relative to ~ch other. I~ this case, at the outpu~ o~ ~he gate 47 (~ig. 11) there are formed synchronized clock pulses (Fig. 12d), whereas at the output of the gate 48 (Fig.11) there are ~oxmed sy~chronizing clock pulses (~ig. 12e).
The repetition.~freque~cy f1 of the synchIonized cloc'~
pulses is equal to the repetition frequency ~2 of ~he syn-chro~izing clock pulses which is , . .
f1 - 3 f2 = 1/2 fO (2) ,; .
where fO is the repetition ~reque~cy of the pulses arrivi~g ~ from the output 15 (~ig. 6) o~ the clock pulse generator 2.
'. The synchronized clock pulses are applied to the out-.l put 16 o~ the sy~chronizer 3.
.1 ~he s~nchronizing clock pulses are applied to the in-~ .puts o~ the A~D circuit 53 (~ig~ and to the inputs o~
vl the gate 55 of the sy~chronizing eleme~t 44~ as well as to the inputs of the A~-D circuit 5~ and to the inputs o~ the . gate 56 o~ the synchro~izing element 45.
In the initial state, ~ll the flip-flops 49, ~0, 51, 52 i are zeroed by a~ initial setting key not shown in ~ig~ 11.

,~
- 35 ~

- ' .
.
, - l~Z3(~9~3 When from an output of a converter 1 tFig. 6) a code pulse (Fig. 12f) arrives corresponding to the positive increment of temperature on the cooling curve, the flip-flop 49 (Fig. 11) is set in the unity state (Fig. 12g). After the state of the flip-flop 49 has been changed (Fig. 11), at the moment ~Jhen a successive synchronizing clock pulse is applied, a pulse (Fig. 12h) app~ars at the output of the AND circuit 53. This pulse will set the buffer flip-flop 51 (Fig. 11) in the unity state (Fig. 12j) thus opening the gate 55~(Fig. 11). At the moment of arrival of a successive synchronizing clock pulse (Figs. 12e, i) at the output of the gate 55 (Fig. 11) a synchronized code pulse (Fig. 12k) is formed corresponding to a positive increment of temperature. This pulse is applied to the output 17 (Fig. 6) of the synchronization unit 3 and to the inputs of trigger 49 and 51 (Fig~ 11).
In this case, the signal (Fig. 12i) arriving from the zero output of the flip-flop 51 (Fig. 11) at one of the inputs of the AND circuit 53 precludes the arrival of the signal at the unity input of the flip~flop 51 at the moment, when a pulse is applied to the zero input of the trigger 51. The formed synchronized code pulse sets flip flops 49 and 51 to a zero state, thus preparing the synchronizing element 44 for receiving the next code pulse.

During operation of the synchronizing element 44, the code pulse may partially coincide in time with the synchronizing clock pulse. This may result in an inadequate pulse 59 (Fig. 12h~ at the output of the AND circuit 53 (Fig. 11), for example, a pulse having an insufficient dura-tion or amplitude. When such inadequate pulse occurs, the buffer flip-flop 51 may continue to remain in the zero state until there is applied another synchronizing clock pulse to the input of the AND circuit 53. Insofar as at the moment of the arrival of the next synchronizing clock pulse, the flip-flop ' state cannot change any longer, at the output of the AND
circuit 53 at the instant in time there appears a second (adequate) pulse 60 (Fig. 12h). This pulse sets the flip-flop 51 (Fig. 11) in the unity state. At the moment of arrival OL a successive synchronizing clock pulse (Fig. 12e), at the output of the gate 55 a synchronized code pulse (Fig. 12k) is formed whlch is applied to the output 17 (Fig. 6) of the synchronizer 3 with simultaneous setting the flip-flop 49 and 51 in the zero state.
In a similar way at the output of the gate 56 of the synchronizing element 45, there are synchronized code pulses formed corresponding to a negative increment of temperature.
These pulses are fed to the output 18 (Fig. 6~ of the synchronization unit 3.

ILZ35~
:

- ~hus, the coincide~ce in time o~ the pulses formed a~
the outputs of the gates 55 a~d 56 (Fi~. 11) with the pulses arriving from the ou~pu~ of the gate 48 o~ the pulse distri-. ~ c~ o ~
buting element 43 ensures ~e~s-i~n in ti~e of the synchroni-zed cloc~ puls~s and the sy~chro~ized code pulses.
To provide reliable operation of ~he syncnro~izer 3, it is necessar~ that the repetition frequenc~ f2 of the ;, synchxo~izlng clock pulses should be two or three times , greater than the ma~imum repetition fre~uency ~3 max f j the code ~ulses arrivi~g from the output o~ the ~onverter y (~ig. 6) 9 i.e.
i .
, i - .
.,'3 ~2 ~ 3 ~3max (~) . .
,, .
e~ce the pulse ~reque~cy at bhe output o~ the genera tor 2 must be .. , ~
, ~o = 2 ~2 ~ 6 f3 (4) l'he selector 11 o~ signs o~ the thermal ef~ect of phase tra~sLormatio~, show~ in ~ig~ 13, operates as follows~ In the process o~ the metal or alloy cooling, the code combi-natio~s ~rom the i~ormation outputs (digit outputs) o~
the registers 5,8 and of the counters 9 and 10~ are fed to the i~puts o~ the decoder 57. ~s soo~ as any o~ the : code csmbinations o~ the parameters ~, Q ~, t 9 and satisfyi~g ~ormula (1), is applied to the inputs o~ the decoder 57 at one o~ the outputs o~ the decoder 57 ~æ~
,' :,, - ~8 -. . . - " - . . ..
.. . . . ..

: ' ''' ' '. ' , ~ ':
.,:, , .

.~ .

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there is ~ormed a sig~al being fed~ ~hrough the 'tOR" cir-cuit, to the output 27 of the solector 11.
The employment in the a~gregate o~ ~ain parame-ters of the process of cooling of metal 4r alloy~allows the tem-perature arrests caused both by the thermal e~fect and oy the pseudothermal e~fect to be distinOuished even in such cases ~Ihen these temperature arrests are o~ the equal duration, which, as a whole~ improves ~ reliability of discriminating the thermal el~ect of phase transformation.

.

.,;

Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for discriminating the thermal effect of phase transformation of metals and alloys in the process of their cooling, comprising the steps of: cooling the metal or alloy at a measured temperature; establishing an increment of said temperature relative to a maximum temperature recorded during temperature measurement; calculating a threshold of duration of a temperature arrest after time elapsed since the start of temperature measurement making a decision is made ascertaining the occurrence of the thermal effect of phase transformation, said threshold being calculated as a function of (a) the temperature of the metal or alloy being cooled, (b) an increment of said temperature relative to the maximum temperature recorded during the temperature measuring cycle, and (c) the time elapsed since the start of said temperature measuring cycle; cooling metal or alloy and measuring the duration of the temperature arrest during cooling; comparing the measured duration of the temperature arrest with the threshold value of the duration of the temperature arrest calculated for the moment when said temperature arrest occurs; and ascertaining the occurrence of the thermal effect of phase transformation when measured duration of temperature arrest exceeds predetermined threshold of the duration of temperature arrest.

2. An apparatus for discriminating the thermal effect of phase transformation of metals and alloys in the process of their cooling, comprising: a converter for converting tem-perature into a digital. pulse code, said converter having an input to which there is applied a signal carrying information relative to temperature of a metal or alloy being cooled; a first output forked pulses corresponding to a positive increment of temperature; a second output for code pulses corresponding to a negative increment of temperature; a clock pulse generator having an output; a synchronization unit for distributing in time code a clock pulses, having first and second inputs respectively connected to said first and second outputs of said converter for converting temperature into digital pulse code;
a third input connected to said output of said clock pulse generator; a first output for code pulses corresponding to a positive increment of temperature, a second output for syn-chronized code pulses corresponding to a negative increment of temperature; an output of synchronized clock pulses; a re-versible counter for generating a parallel temperature code, having an add input connected to said first output of said synchronization unit, a subtract input connected to said output of said synchronization unit, and an information output; a threshold counter for determining local increments of tempera-ture, having an add input connected to said first output of said synchronization unit, a subtract input connected to said second output of said synchronization unit, an input for count blocking, a first overflow output for delivering pulses at the instant of time when the positive increment of temperature assumes a predetermined value, a second overflow output for delivering pulses at the instant of time when a negative increment of temperature assumes a predetermined value; a cycle counter for determining the time elapsed since start of the temperature measuring cycle, having a count input connected to said output of synchronized clock pulses of said synchronization element, an information output of a parallel code of the time interval elapsed since the start of the temperature measuring cycle; a first register for storing a parallel code of metal or alloy temperature at a successive instant of time when the increment of temperature assumes a predetermined value, having an infor-mation input connected to digit outputs of said reversible counter, a first and a second control inputs, and an information output; a second register for storing a parallel code of the time interval elapsed since the start of the temperature measuring cycle until the next successive moment when the in-crement of temperature assumes a predetermined value, having an information input connected to said information output of said cycle counter, a first and a second control inputs, and an information output; a counter of time intervals for determining the time metered from the next successive moment when a local increment of temperature assumes a predetermined value, and having a count input connected to said output of synchronized clock pulses of said synchronization unit, a first input of initial setting combined with said first control inputs of said first and second registers, being connected to said overflow output of said threshold counter, a second input of initial setting combined with said second control inputs of said first and second registers being connected to said second overflow output of said threshold counter, a counter blocking input, an information output; a temperature increment counter for determining an increment of temperature relative to the maximum temperature recorded during the temperature measuring cycle, having a counting input connected to said second overflow output of said threshold counter, and an information output; a selector of signs of the thermal effect of phase transformation, having a first input connected to said information output of said first register, receiving therefrom information on the current temperature, a second input connected to said information output of said counter of temperature increments, receiving therefrom information on the current negative increment of temperature relative to the maximum temperature recorded during the measuring cycle, a third input connected to said information output of said second register and receiving therefrom information on the time interval elapsed since the start of the temperature measuring cycle, a forth input connected to said information output of said time interval counter and receiving therefrom information on the time being metered from the next successive moment when the increment of temperature assumes a predetermined value, and an output for delivering a signal at the moment when the decision on the presence of the thermal effect of phase trans-formation is taken, connected to said count clocking inputs of said time interval counter and said threshold counter.