SU1280039A1

SU1280039A1 - Cast iron

Info

Publication number: SU1280039A1
Application number: SU843698274A
Authority: SU
Inventors: Тамара Ивановна Корягина; Олег Владимирович Чернецкий; Юрий Дмитриевич Корягин
Original assignee: Челябинский Политехнический Институт Им.Ленинского Комсомола
Priority date: 1984-02-03
Filing date: 1984-02-03
Publication date: 1986-12-30

Abstract

Изобретение относитс к области металлургии, в частности к износостойким чугунам, используемым дл изготовлени деталей, работающих в услови х интенсивного абразивного изнашивани . Цель изобретени - измельчение карбидной фазы и повьшение теплостойкости. Чугун предложенного состава содержит, мас.%: углерод 2,03 ,5j кремний 0,8-1,0; марганец 0,30 ,6; хром 12,0-20,0; ванадий 3,2-4,0; молибден 0,5-0,9, алюминий 0,05-0,15; кальций 0,001-0,05J церий 0,11-0,2; иттрий 0,05-0,09; железо - остальное. Совместное модифицирование хромованадиевого чугуна иттрием и церием сопровождаетс повышением его теплостойкости , измельчением структуры, измельчением карбидной фазы при иза менении среднего размера карбидных частиц до 2,01 мкм, сохранением мелСЛ козернистой структуры до повьппенных температур нагрева The invention relates to the field of metallurgy, in particular to wear-resistant cast irons, used for the manufacture of parts operating under conditions of intensive abrasive wear. The purpose of the invention is the grinding of the carbide phase and the increase in heat resistance. Cast iron of the proposed composition contains, wt%: carbon 2.03, 5j silicon 0.8-1.0; manganese 0.30, 6; chromium 12.0-20.0; vanadium 3.2-4.0; molybdenum 0.5-0.9, aluminum 0.05-0.15; calcium 0.001-0.05J cerium 0.11-0.2; yttrium 0.05-0.09; iron - the rest. The joint modification of chromium-vanadium cast iron with yttrium and cerium is accompanied by an increase in its heat resistance, grinding of the structure, grinding of the carbide phase with a change in the average size of carbide particles to 2.01 μm, retaining the fine grain structure to the heating temperature

Description

Изобретение относитс к металлургии , в частности к износостойким чугунам, используемьм дл изготовлени деталей;, работающих в услови х интенсивного абразивного изнашивани .The invention relates to metallurgy, in particular to wear-resistant cast irons, used for the manufacture of parts; working under conditions of intensive abrasive wear.

Целью изобретени вл етс измельчение карбидной фазы и повышение теплостойкости чугуна.The aim of the invention is to grind the carbide phase and increase the heat resistance of the iron.

Пример . Чугун выплавл ют в индукционной печи емкость б 60 кг с основной футеровкой. В качестве шихты используют стальные отходы, ферро сплавы и специальные присадки. Предлагаемьй состав чугуна можно получить любым из известных способов - вводом элементов или их соединений в ковш ил в электропечь.An example. The cast iron is melted in an induction furnace with a capacity of 60 kg with a base lining. Steel waste, ferro alloys and special additives are used as a charge. The proposed composition of cast iron can be obtained by any of the known methods - the introduction of elements or their compounds into the ladle or into the electric furnace.

Дл получени мелкозернистой мар- .тенситно-аустенитной ртруктуры с рав номерно распределенными в ней дисперсными карбидами хрома, молибдена и ванади , определ ющими высокую твердость и износостойкость, отливки подвергают закалке 1000-1050 С и часовому отпуску при 180±5 С, а дл ;абеспечени теплостойкости - закалке от 1150±5°С и двукратному головному отпуску при 54015 С.To obtain fine-grained martensite-austenitic structure with dispersed chromium, molybdenum and vanadium carbides uniformly distributed in it, which determine high hardness and wear resistance, castings are subjected to quenching of 1000-1050 C and hour tempering at 180 ± 5 C, and for; Absence of heat resistance - quenching from 1150 ± 5 ° С and double head tempering at 54015 С.

Химический состав чугуна выбран, исход из следующих соображений.The chemical composition of cast iron is selected based on the following considerations.

Содержание кремни составл ет 0,8 1,0%. Верхний предел по содержанию кремни 1,0% определен, исход из прокаливаемости чугунов данного сое- The silicon content is 0.8-1.0%. The upper limit for the silicon content of 1.0% is determined, based on the hardenability of the cast iron of this compound.

тава, котора резко снижаетс при увеличении содержани кремни более 1%. Снижение прокаливаемости отрицательно сказываетс на износостойкости чугунов.tava, which decreases sharply with increasing silicon content more than 1%. A decrease in hardenability adversely affects the wear resistance of the cast iron.

Введение в чугун хрома в количестве 2,0-20% при заданном в указанных пределах содержании углерода и ванади оказывает решающее воздействие на формирование структуры, износостойкость и теплостойкость чугуна. В предлагаемом чугуне образуютс карбиды тригонального типа (Сг, Fe)C с микротвердостью 13000-21000 МПа и кубический карбид VC с микротвердос- тью 30000 МПа. При кристаллизации чугуна указанного состава, содержащих карбиды (Сг Fe)C-j, формируетс The introduction of chromium in cast iron in the amount of 2.0-20% at a given carbon and vanadium content within the specified limits has a decisive influence on the formation of the structure, wear resistance and heat resistance of the iron. In the proposed iron, carbides of trigonal type (Cr, Fe) C with a microhardness of 13000-21000 MPa and cubic carbide VC with a microhardness of 30,000 MPa are formed. During the crystallization of cast iron of the indicated composition containing carbides (Cg Fe) C – j,

Введение алюмини более 0,15% Предлагаемьй чугун нежелательно, как это приводит к росту зерна прThe introduction of aluminum more than 0.15% of the proposed iron is undesirable, as this leads to the growth of grain pr

р да дефектов: наблюдаютс сколыp yes defects: chipped

аустенитохромистокарбидна эвтектика , имеюща скелетное строение, в KO-,J нагреве и способствует по влению торой матричной фазой вл етс аусте- нит. Эти особенности эвтектики и наличие высокотвердых дисперсных карбидов хрома и ванади определ ют высов изломе и увеличиваетс склоннос к хрупкому межкристаллическому ра рушению.The austenitic chromatic carbide eutectic, which has a skeletal structure, is heated in KO-, J and contributes to the appearance of the second matrix phase austenite. These features of the eutectic and the presence of highly solid dispersed chromium and vanadium carbides determine the height of the fracture and the tendency to brittle intercrystalline degradation increases.

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кую износостойкость и теплостойкость чугуна.wear resistance and heat resistance of cast iron.

Введение в чугун кальци основано на его взаимодействии с серой. При содержании серы в чугуне до 0,03% дл полной десульфурации достаточно до 0,05% кальци . Более высокое содержание кальци приводит к образованию большого количества неметаллических включаний, в том числе и с РЗМ, что сопровождаетс снижением механических свойств. Поэтому верхнее содержание кальци ограничиваетс пределом 0,05%.Introduction to calcium iron is based on its interaction with sulfur. When the sulfur content in the pig iron is up to 0.03%, up to 0.05% calcium is sufficient for complete desulfurization. A higher calcium content leads to the formation of a large number of non-metallic inclusions, including those with REM, which is accompanied by a decrease in mechanical properties. Therefore, the upper calcium content is limited to 0.05%.

Модифицирование иттрием в предложенных пределах обеспечивает резкое измельчение структуры, что сопровождаетс повышением механических свойств чугуна, в частности предела прочности на изгиб.Modification with yttrium in the proposed limits provides a sharp comminution of the structure, which is accompanied by an increase in the mechanical properties of cast iron, in particular, the bending strength.

Церий повышает эффективность действи иттри , способствует его более глубокому усвоению жидким металлом и оказывает также модифицируюш;ий эффект, создава дополнительные центры кристаллизации. Кроме того, церий способствует очищению границ зерен от неметаллических включений и измельчает зерно, повьша механические свойства сплава.Cerium increases the efficiency of yttrium, contributes to its deeper absorption by the liquid metal and also has a modifying effect, creating additional crystallization centers. In addition, cerium helps to clean the grain boundaries from non-metallic inclusions and crushes the grain, increasing the mechanical properties of the alloy.

Нижний предел содержани иттри и цери обеспечивает наличие модифицирующего эффекта и повьшение свойств .чугуна, а верхний предел (соответ- ственно 0,09% и 0,2%) вл етс границей положительного воздействи этих ингредиентов на структуру и свойства чугуна, т.к. дальнейшее по- вьш1ение их концентрации приводит к снижению механических свойств и ударной в зкости.The lower limit of the content of yttrium and cerium ensures the presence of a modifying effect and an increase in the properties of cast iron, and the upper limit (respectively, 0.09% and 0.2%) is the limit of the positive effect of these ingredients on the structure and properties of cast iron, since a further increase in their concentration leads to a decrease in mechanical properties and toughness.

Нижний предел по содержанию алюмини определ етс его минимальным количеством, начина с которого алюминий вл етс не только раскисли- телем, но и оказывает вли ние на размер зерна, измельча его, а также способствует рафинированию межфазнык границ и увеличивает однородность состава.The lower limit on the aluminum content is determined by its minimum amount, starting from which aluminum is not only a deoxidizing agent, but also affects the grain size, grinding it, and also contributes to the refining of interfacial boundaries and increases the uniformity of the composition.

Введение алюмини более 0,15% в Предлагаемьй чугун нежелательно, так как это приводит к росту зерна приThe introduction of aluminum more than 0.15% in iron ore is undesirable because it leads to grain growth with

нагреве и способствует по влению heat and promote the appearance

р да дефектов: наблюдаютс сколыp yes defects: chipped

в изломе и увеличиваетс склонность к хрупкому межкристаллическому разрушению .in the fracture and increases the propensity for brittle intergranular fracture.

Введение молибдена в чугун способствует улучшению прокаливаемости сплава, повышению износоустойчивости и устойчивости против отпуска. Нижний предел содержани молибдена (0,5%) установлен с учетом его вли ни на прокаливаемость чугуна и минимально необходимого количества, необходимого дл заметного повьштени устойчивости чугуна против отпуска. Верхний предел по содержанию молибдена дл предлагаемых составов (0,9%) определ етс , исход из того, что повьпиение концентрации молибдена свыше 0,9% приводит к интенсивному 5 обезуглероживанию сплавов при нагреве под закалку и понижению их износостойкости .The introduction of molybdenum in cast iron improves the hardenability of the alloy, improving wear resistance and resistance to tempering. The lower limit of the molybdenum content (0.5%) is set taking into account its effect on the hardenability of the pig iron and the minimum amount needed to noticeably increase the stability of the pig iron against tempering. The upper limit for the content of molybdenum for the proposed compositions (0.9%) is determined on the basis that the concentration of molybdenum in excess of 0.9% leads to an intense decarburization of alloys during heating for quenching and a decrease in their wear resistance.

Химический состав, размеры карбидры ..Наблюдаетс утонение осей денд- ритов и их Дробление. Изменилась структура эвтектики: эвтектические карбиды при модифицировании дробились 5 и принимали форму, близкую к округлой . Средний размер карбидных частиц уменьшилс с m 5,11 мкм и 1 11,56 мкм, до m 3,62 мкм и 1 8,04 мкм. В целом по сечению структура стала более однородной.Chemical composition, size of carbide. Thindendritic axes are thinned and crushed. The structure of the eutectic has changed: eutectic carbides were crushed during the modification of 5 and took a form that is close to rounded. The average size of the carbide particles was reduced from m 5.11 µm and 1 11.56 µm, to m 3.62 µm and 1 8.04 µm. In general, the cross section structure has become more uniform.

Структура закаленных от немодифицированных и модифицированных сплавов отличаетс как размерами карбидных частиц, так и степенью однородности . Средний размер карбидных частиц составл ет у немодифйцирован- ного чугуна 3,56 мкм, а у модифицированного - 2,01 мкм.The structure of quenched from unmodified and modified alloys differs in both the size of the carbide particles and the degree of homogeneity. The average size of carbide particles in unmodified cast iron is 3.56 µm, and that of the modified iron is 2.01 µm.

Кроме того, структура модифицироfOIn addition, the structure is modified

ных частиц и теплостойкость предлага-20 ванного чугуна сохран етс мелкозерparticles and the heat resistance of the proposed-20 bathing iron remains fine-grained

емых и известных чугунов приведены в таблице. Дл определени теплостойкости термообработанные образцы чугунов указанных составов термообра- батывали на вторичную твердость (закалка от 1150i5 C и двухкратный часовой отпуск при 540±5 С) и подвергали их часовому нагреву при 520, 530, 540, 550, 560, 570, 580, 590 и 600°С, а затем в охлажденных до комнатной температуры образцах замер ли твердость.eminent and famous cast iron in the table. To determine the heat resistance, the heat-treated samples of cast iron of these compositions were heat-treated to secondary hardness (quenching from 1150i5 C and two-time tempering at 540 ± 5 C) and subjected to hour heating at 520, 530, 540, 550, 560, 570, 580, 590 and 600 ° C, and then the hardness was measured in samples cooled to room temperature.

. Дл исследованных чугунов принимали , что теплостойкость должна обеспечить твердость не менее 58HRC пос- ле 4-часового нагрева при указанных температурах.. For the investigated cast irons, it was assumed that the heat resistance should provide a hardness of at least 58 HRC after 4 hours of heating at the indicated temperatures.

Анализ таблицы показывает, что чугун составов 1-11 имеет размеры карбидных частиц в литом состо нии значительно меньше, чем чугун составов 12 и 13.Analysis of the table shows that the cast iron of compositions 1-11 has the dimensions of carbide particles in the cast state is significantly smaller than the cast iron of compositions 12 and 13.

Теплостойкость чугуна составов 1-11, обеспечивающа твердость не ме JHee 58 HRC после 4-часового нагрева, составл ет 570-580°С, а теплостойкость чугуна составов 12 и 14 - 550 560°С соответственно. Наиболее низка теплостойкость у чугуна состава 13 (530 С).The heat resistance of the cast iron of compositions 1-11, providing a hardness of not less than JHee 58 HRC after 4 hours of heating, is 570-580 ° C, and the heat resistance of cast iron of compositions 12 and 14 is 550 560 ° C, respectively. The lowest heat resistance of cast iron composition 13 (530 C).

Изучение микроструктуры сплавов (немодифицированного и модифицированного чугуна 280X19ФЗ,5) в литом состо нии показало, что модифицирование Ce+Y уменьшает дендрйтность структу- Studying the microstructure of alloys (unmodified and modified cast iron 280X19FZ, 5) in a cast state showed that modifying Ce + Y reduces the structure dendritity

) 5 ) five

28003942800394

ры..Наблюдаетс утонение осей денд- ритов и их Дробление. Изменилась структура эвтектики: эвтектические карбиды при модифицировании дробились 5 и принимали форму, близкую к округлой . Средний размер карбидных частиц уменьшилс с m 5,11 мкм и 1 11,56 мкм, до m 3,62 мкм и 1 8,04 мкм. В целом по сечению структура стала более однородной.ry. There is observed a thinning of the axes of the dendrites and their fragmentation. The structure of the eutectic has changed: eutectic carbides were crushed during the modification of 5 and took a form that is close to rounded. The average size of the carbide particles was reduced from m 5.11 µm and 1 11.56 µm, to m 3.62 µm and 1 8.04 µm. In general, the cross section structure has become more uniform.

нистой после закалки от температуры . 1150 с, тогда как в немодифицированном чугуне наблюдаетс укрупнение зерна. Таким образом, модифицирование хромованадиевых чугунов сопровождаетс : измельчением структуры, при одновременном увеличении ее однородности по сечению отливки, измельчением карбидной фазы при изменении среднего размера карбидных частиц с 3,56 до 2,01 мкм, сохранением мелкозернистой структуры до повышенных температур нагрева (.hardened after tempering on temperature. 1150 seconds, whereas in the unmodified iron, grain enlargement is observed. Thus, the modification of chromium-vanadium cast irons is accompanied by: grinding the structure, while increasing its uniformity over the cross section of the casting, grinding the carbide phase while changing the average size of the carbide particles from 3.56 to 2.01 µm, maintaining the fine-grained structure to elevated heating temperatures (.

Claims

The invention relates to metallurgy, in particular to wear-resistant cast irons, used for the manufacture of parts; working under conditions of intensive abrasive wear. The aim of the invention is to grind the carbide phase and increase the heat resistance of the cast iron. An example. The cast iron is melted in an induction furnace with a capacity of 60 kg with a base lining. Steel waste, ferroalloys and special additives are used as a charge. The proposed composition of cast iron can be obtained by any of the known methods by introducing elements or their compounds into the ladle or into the electric furnace. In order to obtain fine-grained mar.tusitic-austenitic structure with uniformly dispersed chromium, molybdenum, and vanadium carbides distributed in it, which determine high hardness and wear resistance, castings are subjected to quenching of 1000-1050 C and hour tempering at 180 ± 5 C, and length; The lack of heat resistance - quenching from 1150 ± 5 ° С and double head tempering at 54015 С. The chemical composition of cast iron is selected, based on the following considerations. The silicon content is 0.8-1.0%. The upper limit for the silicon content of 1.0% is determined, based on the hardenability of the iron of this Soetava, which decreases sharply with increasing silicon content of more than 1%. A decrease in hardenability adversely affects the wear resistance of the cast iron. The introduction of 2.0–20% of chromium in cast iron at a given carbon and vanadium content within the specified limits has a decisive effect on the formation of the structure, wear resistance and heat resistance of the cast iron. In the proposed iron, trigonal type carbides (Cr, Fe) C with a microhardness of 13000-21000 MPa and cubic carbide VC with a microhardness of 30,000 MPa are formed. During the crystallization of cast iron of the indicated composition, containing carbides (Cr Fe) C – j, an austenitic-chromic-carbide eutectic having a skeletal structure is formed, in the KO, which is the austenitic matrix phase. These features of the eutectic and the presence of highly solid dispersed carbides of chromium and vanadium determine the high wear resistance and heat resistance of cast iron. Introduction to calcium iron is based on its interaction with sulfur. When the sulfur content in the pig iron is up to 0.03%, up to 0.05% calcium is sufficient for complete desulfurization. A higher calcium content leads to the formation of a large number of non-metallic inclusions, including those with REM, which is accompanied by a decrease in mechanical properties. Therefore, the upper calcium content is limited to 0.05%. Modification with yttrium in the proposed limits provides a sharp comminution of the structure, which is accompanied by an increase in the mechanical properties of cast iron, in particular, the bending strength. Cerium increases the efficiency of yttrium, contributes to its deeper absorption by the liquid metal and also has a modifying effect, creating additional crystallization centers. In addition, cerium helps to clean the grain boundaries from non-metallic inclusions and crushes the grain, increasing the mechanical properties of the alloy. The lower limit of the content of yttrium and cerium ensures the presence of a modifying effect and an increase in the properties of cast iron, and the upper limit (respectively, 0.09% and 0.2%) is the limit of the positive effect of these ingredients on the structure and properties of cast iron, since a further increase in their concentration leads to a decrease in mechanical properties and toughness. The lower limit on the aluminum content is determined by its minimum quantity, starting from which aluminum is not only a deoxidizer, but also affects the grain size , grinding it, and also contributes to the refining of interfacial boundaries and increases the uniformity of the composition. The introduction of aluminum more than 0.15% in the proposed cast iron is undesirable because it leads to grain growth during heating and contributes to the appearance of a number of defects: chipped fractures are observed and increases tendency to brittle intergranular destruction. The introduction of molybdenum into cast iron improves the hardenability of the alloy, increases durability and resistance against tempering. The lower limit of the molybdenum content (0.5%) is set taking into account its effect on the hardenability of cast iron and the minimum required amount necessary for a noticeable increase in the stability of cast iron against tempering. The upper limit for the content of molybdenum for the proposed compositions (0.9% is determined on the basis that the concentration of molybdenum over 0.9% leads to intensive decarburization of alloys during heating for quenching and a decrease in their wear resistance. Chemical composition, size of carbide particles and heat resistance of the proposed and known cast irons are given in Table 1. To determine the heat resistance of the bone, the heat-treated samples of the cast iron of the indicated compositions were thermo-treated to secondary hardness (for 1150i5C and two times tempering at 540 ± 5 C) and subjected them to hour heating at 520, 530, 540, 550, 560, 570, 580, 590, and 600 ° C, and then the hardness was measured in samples cooled to room temperature. It was assumed that heat resistance should both bake a hardness of at least 58HRC after 4 hours of heating at the indicated temperatures. Analysis of the table shows that the cast iron of compositions 1-11 has dimensions of carbide particles in the cast state much less than the cast iron of compositions 12 and 13. Heat resistance cast iron of compositions 1-11, providing a hardness of not JHee 58 HRC after 4 hours Heating is 570-580 ° C, and the heat resistance of cast iron of compositions 12 and 14 is 550 560 ° C, respectively. The lowest heat resistance in cast iron composition 13 (530С). The study of the microstructure of alloys (unmodified and modified cast iron 280X19FZ, 5) in a cast state showed that modifying Ce + Y reduces the structure dendritity of 94 ry. There is a thinning of the axes of dendrites and their fragmentation. The structure of the eutectic has changed: eutectic carbides, when modifying, were crushed and took a shape that was close to rounded. The average size of the carbide particles was reduced from m 5.11 µm and 1 11.56 µm, to m 3.62 µm and 1 8.04 µm. In general, the cross section structure has become more uniform. The structure of quenched from unmodified and modified alloys differs in both the size of the carbide particles and the degree of homogeneity. The average size of carbide particles is 3.56 µm for unmodified cast iron, and 2.01 µm for modified one. In addition, the structure of the modified cast iron is kept fine-grained after quenching on temperature. 1150c, whereas in the unmodified iron, grain coarsening is observed. Thus, the modification of chromium-vanadium cast irons is accompanied by: grinding the structure, while increasing its uniformity over the section of the casting, grinding the carbide phase when the average size of the carbide particles is changed from 3.56 to 2.01 microns, preserving the fine-grained structure to elevated heating temperatures (. Claims of invention: Cast iron containing carbon, silicon, manganese, chromium, vanadium, molybdenum, aluminum, calcium, cerium and iron, differing in that, in order to grind the carbide phase and increase heat resistance, it additionally contains yttrium, in the following ratio of components, wt.%: 2.0-3.5 Carbon 0.8-1.0 Silicon 0.3-0.6 Manganese 12.0-20.0 3.2-4.0 Vanadium 0.5-0.9 Molybdenum 0.05-0.15 ALUMINUM 0.001-0.05 Calcium 0.11-0.2 0.05-0, 09 Yttrium Else. Iron

eight

1280039 Continuation of the table

It was assumed that the heat resistance should, after 4 hours of heating at the indicated temperatures, provide a hardness of at least 58 HRC temperatures.