Estimation of a resource of plasticity brasses with the increased contents of lead
Equipment is created for conducting of researches which are directed on the decision of problem a painting of hexahedral brass standards with maintenance of lead within the limits of 2-3%, the result of test is resulted on sinking.
Now to quality of made production the increasing requirements are showed. In this connection forecasting of quality of made production is one of actual directions.
One of possible variants of forecasting of quality of production is the experimental research of a resource of plasticity of metal.
For definition of a resource of plasticity of superficial layers of metal it is possible to use the following techniques:
- the technique described in work by A.A.Bagatova, etc. [1]. At use of this technique by the basic requirements to tests the constancy of an intense condition and preservation of monotony of deformation is during all experience, high accuracy of definition of parameters tensely - deformed conditions in a place of destruction, and also simplicity of realization of test;
- A.G.Smirnova-Aljaeva's technique [2], which assumes carrying out of test on a deposit about reception of the exact data, such as relative shortening a sample and effort of compression, for the further calculations and reception of the dependences necessary for forecasting of quality of a surface of metal.
So each of above mentioned techniques demands the equipment which will allow to receive exact experimental data, such as dependence of moving of the working tool in time and effort of pressing. It is possible to achieve due to creation of the test bed with use of modern digital technologies. In this case use of new digital technologies means use of gauges of pressure and moving for removal of the data and the module for their processing. Use of the given equipment to allow to simplify process of processing of experimental data and will allow to depart use hardcount oscillograms which turn out at use of a recorder established on laboratory press.
Thus, modernization laboratory press was carried out under the following circuit:
- gauges of pressure and moving have been established;
- module SDI-ADC16-32F of firm is connected to a personal computer the Data of Saturn Internationa;
- program «Сталедав» was creating for data processing removed is created by means of the module.
The laboratory stand has been created on base press 250 P with the maximal loading 2500 кN and height of the worker of space 1000 mm. Dimensions press – 2,1x0,9x2,7 m, weight – 3530 kg.
On press the gauge of moving and the gauge of pressure are established. The gauge of pressure allows to fix pressure of a working liquid in hydrosystem press, the gauge of moving – moving of the bottom plate press.
The characteristics of gauges of moving and pressure are resulted in tabl. 1.
| Tabl.1 – The characteristics of gauges of moving and pressure |
| The gauge of pressure ADZ-SML-10 |
Potenciometrics gauges of moving MMS33 |
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| from - 1,0 up to 4000bar |
50...900 mm |
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Shock loading
30g with time 14 ms;
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Vibration loading
25g 20 – 2000Gc
Returnable movements 50 Mio.
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The order of connection of the equipment is shown on fig. 1.
Fig. 1 – the Circuit of an arrangement of the equipment at the laboratory stand
The laboratory stand will consist of the loading device 1, a control panel 2 and is established on the base 6, has top 7 and the bottom 8 basic plates, a safety casing 9, the electric motor 10. The loading device represents a frame which will consist of the base and traverses, connected to two carving colums. Moving traverses on carving column is made from the electric motor 10 with the help of a worm-helical gear. The top basic plate 7 is fixed on mobile traverse and has a spherical support. The back side press on a bed 11 the gauge of moving 5 which rod is attached to the bottom plate 8 is established. In a bed 11 loading devices are the cylinder 12 with a basic table. Under action of oil in hydrosystem planger moves upwards. In forcemeasured the block the gauge of pressure 4 is located. The information from the gauge of pressure and the gauge of moving acts on ACP 13. The processed information with ACP is deduced on the display of a personal computer 14.
The information from gauges is exposed to numbering in module SDI-ADC16-32F of firm the international Data of Saturn. As a result of work ACP the data as 16-digit numbers get in program ACP «Сталедав». The data processed in the program, are kept in a file with expansion *.xls.
The created laboratory stand can be applied at the decision trouble tm spalling the metal, arisen at manufacture xeksagon rods by pressing and the subsequent drawing from alloys CuZn39Pb3 and CuZn40Pb2 on Open Society « Artemovsk's factory on processing nonferrous metals ».
Leads brasses of which make hexahedrals rods, possess good making. Lead is insoluble in phases and at all temperatures (down to solidus) is present as an independent phase – practically pure lead. Particles of lead are on borders of grains and from their quantity, sizes and distributions depend the basic properties. Biphase leads a brass (α + β) – a brass can be processed in a hot condition. Leads α–brass are processed in a cold condition, and at the certain modes probably hot pressing [3].
From a set of hexahedral rods O30 mm the sample has been selected from a brass of mark CuZn40Pb2 with the given kind of defect (Fig. 2).
Inside a bowl the dirty (technological greasing) is found out. The bowl has the sizes 0,85x0,51 mm. At research of a microstructure it is established, that β-the phase makes ≈48%, α-the phase is submitted by grains of various forms and directions.
Fig. 2 – the Lateral surface rods with defects, x100
Occurrence of the given kind of a marriage can be caused by the several reasons:
- non-uniform distribution of particles of lead in β-to a phase;
- deviation from the "know-how";
- exhaustion of a resource of plasticity of metal in superficial layers.
The circuit of manufacture brass прутков in conditions of Open Society «Artemov's factory on processing nonferrous metals» is submitted below.
From brasses with the maintenance of lead of 2-3 % the ingot in size Æ 185x650 mm.
Further it is made stripping ingots and cutting for measured lengths. Then heating ingots in the heating gas furnace up to temperatures is made: I a zone –÷950°С, II zone – 780÷850°С. The temperature of preparation at the moment of delivery from the furnace makes 700÷760°С.
Pressing is carried out on horizontal hydraulic to press by effort 2000 ts till size Æ19,4mm. Pressing is made with a shirt thickness 0,5÷1,5 mm with application of gydrono-graphite greasing. Heat treatments in a stream of pressing are not present. Then it is made the winding in revolts and transfer on the crosswise store for cooling by water. Unitary drawing is made till size Æ18,0 mm on combined mill firms «Шумаг».
The "know-how" of rods is observed in full, but it does not guarantee high quality of finished goods. In this connection it is possible to assume, that the possible reason of occurrence of a plenty of a marriage is exhaustion of a resource of plasticity of metal in superficial layers of rods.
For confirmation of it it is necessary to carry out test for a deposit, but according to work [1] The degree of deformation of shift at a deposit does not reach great values and at test of samples from plastic materials can appear insufficient for their destructions. Destruction at a deposit is not accompanied by division of a sample into parts. Therefore the certain difficulties arise in an establishment of the moment of formation of macrocracks. For a basis of the further researches the technique of definition of a resource of plasticity of G.A.Smirnova-Aljaeva [2], which assumes carrying out of tests on a deposit for reception of the necessary data for the subsequent calculation of a resource of plasticity.
Preliminary tests for a deposit have been carried out at the laboratory stand. By the assumed as a basis technique samples from pressed hexahedral rods by corresponding GOST of 8817-82 next sizes have been made:
h´0=1,5d´0 and h´´0=0,5h´0.
A deposit it was carried out before full destruction of samples (fig.3). As brass samples have collapsed completely (have broken up into some parts), it allows to use the chosen technique [2] for calculation of a resource of plasticity of investigated samples
Fig. 3 – Appearance of a sample after test
The working window of program «Сталедав» at full destruction of a sample is resulted on fig. 4.
Fig. 4 – The working window of program «Сталедав» at full destruction of a sample.
For the further calculations, experimental data have been processed at use tarirovochni curves received earlier. Curve efforts of pressing are resulted on fig. 5.
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а – h´0 = 1,5d´0
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б – h´´0 = 0,5h´0
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| Fig. 5 – Curve distributions of force in time |
The received curves will allow carry out in further calculation of a resource of plasticity in superficial layers of metal by G.A.Smirnova-Aljaeva's technique.
Conclusions
- the laboratory stand with application of modern digital technologies which allows tests for a deposit with reception of exact experimental data have been created carries out
- the analysis possible the reasons of occurrence of a plenty of a spoilage has been carried out)by manufacture hexahedral rods by pressing and the subsequent drawing from alloys CuZn39Pb3 and CuZn40Pb2 on Open Society «Artemovsk’s factory on processing nonferrous metals»;
- preliminary test for a deposit which has confirmed an opportunity of use of a technique of G.A.Smirnova-Aljaeva for definition of a resource of plasticity in superficial layers of metal has been carried out;
- the following stage of researches carrying out of tests on a deposit ground hexahedrals samples for the data acquisition, necessary for comparison of a resource of plasticity in superficial layers the ground and not ground samples is planned.
The literature
Багатов А.А., Мижинрицкий О.И., Смирнов С.В. Ресурс пластичности металлов при обработке металлов давлением. – М.: Металлургия. – 1984. – 144 с. Смирнов-Аляев Г.А. сопротивление материалов пластическому деформировании. – Ленинград.: Ленинградское отделение машгиза. – 1961. – 464 с. Федоров В.И., Осицев О.Е. Латуни – современный конструкционный материал / Цветные металлы. – 2001. – №8. – С. 92–97.
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