ФОРМИРОВАНИЕ ГРАДИЕНТНЫХ ПОВЕРХНОСТНЫХ СЛОЕВ НЕОДНОКРАТНЫМ ЛАЗЕРНЫМ ЛЕГИРОВАНИЕМ

The capability of deriving laser alloying layers with a smoothly varying gradient of properties was investigated. It was reached by conducting of repeated alloying with a series of lower depth of a melting zone. Obtained nature of allocation structural component and gradient of properties through the thickness, as well as general morphology of the hardened layer have proved a high level of its operation properties in conditions of high contact loading.Исследовали возможность получения лазерно-легированных слоев с плавным градиентом свойств. Это достигалось проведением неоднократного легирования с последовательным уменьшением глубины зоны переплава. Полученный характер распределения структурных составляющих и градиента свойств по глубине, а также общая морфология упрочненного слоя заставляют ожидать высокого уровня его эксплуатационных свойств в условиях высоких контактных нагрузок

СТРУКТУРООБРАЗОВАНИЕ СПЛАВОВ НА ЖЕЛЕЗНОЙ ОСНОВЕ ПОСЛЕ ЛАЗЕРНОГО ЛЕГИРОВАНИЯ

The paper is devoted to investigations on influence of laser treatment regimes of gas-thermal and adhesive coatings from self-fluxing powders on iron basis and after melting with modifying plaster on their roughness and phase composition. One of mathematical planning methods that is a complete factor experiment method has been used for investigation of parameters’ influence on micro-geometry of coatings. The executed investigations have made it possible to observe a general regularity which does not depend on a type of alloying plaster: while increasing speed of laser beam relatively to treated part, beam diameter value of Ra parameter is becoming less. Decrease in height of surface irregularities in case of increasing laser beam speed is related with intensification of evaporation processes. An increase in beam diameter diminishes Ra parameter of the surface. This is due to the fact that decrease in power density occurs at high rate of beam defocusing. Overlapping coefficient does not exert a pronounced effect on Ra parameter of fused coatings. While increasing the speed of laser beam relatively to the part structure is transferred from dendrite into supersaturated one with carbide and boride precipitations. It has been established that technological parameters of laser treatment and particularly speed of laser beam influence on coating composition. While increasing the speed up to v5 = 5 × 10–3 m/s amount of chromium has become larger by 1.5-fold that resulted in increase of micro-hardness of the coating from 9.5–10.1 GPa up to 11.04–15.50 GPa.Статья посвящена изучению влияния режимов лазерной обработки газотермических и клеевых покрытий из самофлюсующихся порошков на железной основе после оплавления с модифицирующими обмазками на их шероховатость и фазовый состав. Для исследования влияния параметров на микрогеометрию покрытий использован один из методов математического планирования – метод полного факторного эксперимента. В результате проведенных исследований прослежена общая закономерность, не зависящая от вида легирующей обмазки: с увеличением скорости луча лазера относительно обрабатываемой детали, диаметра луча значение параметра Ra становится меньше. Уменьшение высоты неровностей поверхности с ростом скорости луча лазера связано с интенсификацией процессов испарения. Увеличение диаметра луча уменьшает параметр Ra поверхности. Это связано с уменьшением плотности мощности при большей степени расфокусирования луча. Коэффициент перекрытия не оказывает заметного влияния на параметр Ra оплавляемых покрытий. С увеличением скорости движения луча лазера относительно детали структура из дендритной превращается в пересыщенную с выделениями карбидов и боридов. Установлено, что технологические параметры лазерной обработки, в частности скорость луча лазера, влияют на состав покрытий. С увеличением скорости до v5 = 5 × 10–3 м/с количество хрома стало больше в 1,5 раза, что привело к повышению микротвердости покрытия от 9,5–10,1 до 11,04–15,50 ГПа

К ОПРЕДЕЛЕНИЮ ВЛИЯНИЯ ВАРЬИРОВАНИЯ РЕЖИМОВ ЛАЗЕРНОЙ ОБРАБОТКИ НА ТРИБОЛОГИЧЕСКИЕ ХАРАКТЕРИСТИКИ РЕЖУЩЕГО ИНСТРУМЕНТА

The paper considers problems pertaining to higher durability and reliability of a cutting tool for cutting gastronomic products while using laser processing that leads to resistance increase of material operating surfaces against impact forces. Influence of laser fusion with additional doping on structure, microhardness, wear resistance for adhesive coatings of Fe–B–Cr–Si system has been studied in the paper. In order to solve a problem for selection of optimal qualitative and subsequently quantitative composition of a multi-component coating a mathematical modeling method using Scheffe’s simplex lattices has been used in the paper. Similar tendency for measuring micro-structure of all adhesive coatings fused by laser beams has been established in the paper. Increase in beam speed has caused the following microstructure changes: cast equilibrium, dendrite, supersaturated boride, carbide and boride. Response surface models have been found and they provide the possibility to assess influence quantity of laser processing parameters on microhardness of adhesive coatings obtained by laser doping and intensity of their wear under various conditions for all investigated compositions.It has been ascertained that there is no strict correlation between hardness and intensity of coating wear after laser doping used for adhesive coatings. This testifies to the fact that hardening has taken place not only due to an increase of carbide-boride phase, but also due to matrix hardening.In addition, a regression model for coating composition effect on tribological characteristics of the adhesive coatings has revealed that an optimal composition of a multicomponent coating ensuring maximum wear resistance of coatings constitutes B4C is 2/3 and 1/3 TaB. It has been determined that hardening of the adhesive coating after laser doping while using multicomponent coating occurs not only due to increase of carbide-boridnoy phase, but also due to matrix hardening.Рассмотрены вопросы повышения стойкости и надежности режущего инструмента для нарезания гастрономических продуктов с помощью лазерной обработки, приводящей к увеличению сопротивления материала рабочих поверхностей ударным нагрузкам. Изучено влияние лазерного оплавления с дополнительным легированием на структуру, микротвердость, износостойкость клеевых покрытий системы Fe–B–Cr–Si. Для решения задачи выбора оптимального качественного, а впоследствии и количественного состава многокомпонентной обмазки использован метод математического моделирования на симплексных решетках Шеффе. Установлена одинаковая тенденция изменения микроструктуры у всех клеевых покрытий, оплавленных лучом лазера. Рост скорости луча лазера вызвал следующие изменения микроструктуры: литая равновесная, дендритная, пересыщенная боридная и карбидо-боридная. Найдены модели поверхностей отклика, позволяющие судить о степени влияния параметров лазерной обработки на микротвердость полученных лазерным легированием клеевых покрытий и интенсивность их изнашивания при различных усилиях для всех исследуемых составов. Установлено, что нет строгой корреляции между твердостью и интенсивностью изнашивания покрытий после лазерного легирования клеевых покрытий. Это говорит о том, что упрочнение произошло не только за счет увеличения карбидо-боридной фазы, но и за счет упрочнения матрицы. Кроме того, регрессионная модель влияния состава обмазки на трибологические характеристики клеевых покрытий показала, что оптимальный состав многокомпонентной обмазки, обеспечивающий максимальную износостойкость покрытий, составляет 2/3В4С и 1/3ТаВ. Установлено, что упрочнение клеевого покрытия после лазерного легирования многокомпонентной обмазкой происходит за счет не только увеличения карбидо-боридной фазы, но и упрочнения матрицы

The tribological properties of ferrous based coatings formed using different technological methods

W artykule przedstawiono wpływ powłok na bazie żelaza o różnym składzie chemicznym, nanoszonych różnymi metodami technologicznymi oraz warunków tarcia na właściwości tribologiczne pary trącej, tj. współczynnik tarcia i intensywność zużycia elementów węzła tarcia. Materiałem, na który nakładano powłokę, była stal C45, grubość powłok znajdowała się w zakresie 0,5-0,7 mm.Plasma-sprayed coatings on the base self-fluxing alloys were investigated. Clean ferrous-based alloy P-Cr16Fe5B4Si4 was used as well as the same with the addition of TaB, MoB, and B4C powders. Fire and laser washing were used to form coatings. The thickness measurements of coatings after processing were from 0.5–0.7 mm, on the base material of steel C45. The metallographic analysis indicated that coating structure depends on the chemical composition of the powder as well as the coating technology. When using an Amsler friction-wear machine, it was determined that when dry technical friction increasingly spreads of torque of friction are observed after some minutes of work, and when oil friction torque are very stable. Additional MoB laser alloying of the coating on a base of P-Cr4Mn2B4Si2V1 powder guarantees a minimal value of the mean friction coefficient. However, the minimal value of the momentary friction coefficient was registered for the coating with additional B4C laser alloying. During dry technical friction, using a coating on a base of P-Cr4Mn2B4Si2V1 powder with additional MoB or B4C laser alloying guarantees a multiple decrease in wear intensity. The presence of oil decreases the influence of material and technology of coating on wear intensity, the difference of values is no more then 20%

PARAMETERS OF LASER PROCESSING AND THEIR INFLUENCE ON TRIBOLOGICAL CHARACTERISTICS OF IRON-BASED COATINGS

The paper considers improvement of physic-mechanical and operational properties of adhesive coatings after laser infusion with additional alloying В4С, ТаВ and МоВ. Influence of the laser infusion with additional alloying on structure, microhardness and wear-resistance of adhesive coatings of the Fe–Cr–B –Si system has been studied in the paper. While increasing a laser beam velocity microstructure is changed from equilibrium to quasi-eutectic. Presence of molybdenum boride and tantalum increases sensitivity of the coating to specific features of laser remelting. In both cases heat exchange conditions have been changed, a number of iron and chromium borides has been increased and due to this molybdenum and tantalum have been partially passing to free state that contributes to a disintegration of structural components. While introducing solid particles B4C into a coating they are dissolved in an iron matrix while being heated by a laser beam and under cooling they are isolated in the form of separated Fe an Cr boride inclusions. Laser infusion and alloying increase coating wear-resistance. Load increase from 30 to 70 Н improves coating wear resistance averagely by 15–26 % and wear resistance of non-alloyed coatings is improved by 26–43 %. An increase of melting rate and laser spot diameter does not exert significant influence on wear but an increase in overlapping coefficient leads to reduction of coating wear. Presence of solid particles in a coating and an increase in rate of melting by laser beam reduce coating wear resistance. Such rather complicated dependence of coating wear rate on conditions of laser melting and wearing process is due to a complex of structural and phase transformations which have contributed to formation of secondary solid inclusions and increased microhardness

TO DETERMINATION OF INFLUENCE FOR VARIATIONS IN LASER TREATMENT MODES ON TRIBOLOGICAL CHARACTERISTICS OF CUTTING TOOL

The paper considers problems pertaining to higher durability and reliability of a cutting tool for cutting gastronomic products while using laser processing that leads to resistance increase of material operating surfaces against impact forces. Influence of laser fusion with additional doping on structure, microhardness, wear resistance for adhesive coatings of Fe–B–Cr–Si system has been studied in the paper. In order to solve a problem for selection of optimal qualitative and subsequently quantitative composition of a multi-component coating a mathematical modeling method using Scheffe’s simplex lattices has been used in the paper. Similar tendency for measuring micro-structure of all adhesive coatings fused by laser beams has been established in the paper. Increase in beam speed has caused the following microstructure changes: cast equilibrium, dendrite, supersaturated boride, carbide and boride. Response surface models have been found and they provide the possibility to assess influence quantity of laser processing parameters on microhardness of adhesive coatings obtained by laser doping and intensity of their wear under various conditions for all investigated compositions.It has been ascertained that there is no strict correlation between hardness and intensity of coating wear after laser doping used for adhesive coatings. This testifies to the fact that hardening has taken place not only due to an increase of carbide-boride phase, but also due to matrix hardening.In addition, a regression model for coating composition effect on tribological characteristics of the adhesive coatings has revealed that an optimal composition of a multicomponent coating ensuring maximum wear resistance of coatings constitutes B4C is 2/3 and 1/3 TaB. It has been determined that hardening of the adhesive coating after laser doping while using multicomponent coating occurs not only due to increase of carbide-boridnoy phase, but also due to matrix hardening

FORMATION OF GRADIENT SURFACE LAYERS BY MEANS OF MULTIFOLD LASER ALLOYING

The capability of deriving laser alloying layers with a smoothly varying gradient of properties was investigated. It was reached by conducting of repeated alloying with a series of lower depth of a melting zone. Obtained nature of allocation structural component and gradient of properties through the thickness, as well as general morphology of the hardened layer have proved a high level of its operation properties in conditions of high contact loading

THE METALLOGRAPHIC ANALYSIS OF STEEL OF H12MF TYPE AFTER TEMPERING BY LASER EMISSION

The article is related to the processes of laser processing. The purpose of work was to optimize technological parameters of the process which would reduce internal tensions in forged piece and would improve quality of surface. The analysis of distribution of elements shows their rather uniform distribution in surface coating. The achieved results have practical importance for optimization of technological parameters and choice of optimal structure and as result of propertie

THE ANALYSIS OF A NUMBER OF PROPERTIES OF H12MF STEEL AFTER HIGH-ENERGY PROCESSING

Laser processing allows to concentrate high level of energy on material surface and the increase of surface hardness can be reached by receiving of uniform fi e-grained structure with impurities of the carbide-containing phases uniformly distributed in matrix. Analysis of properties of H12MF steel after processing by various laser machines was carried out and a number of measures for use of this technology are recommended in the present article

ПАРАМЕТРЫ ЛАЗЕРНОЙ ОБРАБОТКИ И ИХ ВЛИЯНИЕ НА ТРИБОЛОГИЧЕСКИЕ ХАРАКТЕРИСТИКИ ПОКРЫТИЙ НА ОСНОВЕ ЖЕЛЕЗА

The paper considers improvement of physic-mechanical and operational properties of adhesive coatings after laser infusion with additional alloying В4С, ТаВ and МоВ. Influence of the laser infusion with additional alloying on structure, microhardness and wear-resistance of adhesive coatings of the Fe–Cr–B –Si system has been studied in the paper. While increasing a laser beam velocity microstructure is changed from equilibrium to quasi-eutectic. Presence of molybdenum boride and tantalum increases sensitivity of the coating to specific features of laser remelting. In both cases heat exchange conditions have been changed, a number of iron and chromium borides has been increased and due to this molybdenum and tantalum have been partially passing to free state that contributes to a disintegration of structural components. While introducing solid particles B4C into a coating they are dissolved in an iron matrix while being heated by a laser beam and under cooling they are isolated in the form of separated Fe an Cr boride inclusions. Laser infusion and alloying increase coating wear-resistance. Load increase from 30 to 70 Н improves coating wear resistance averagely by 15–26 % and wear resistance of non-alloyed coatings is improved by 26–43 %. An increase of melting rate and laser spot diameter does not exert significant influence on wear but an increase in overlapping coefficient leads to reduction of coating wear. Presence of solid particles in a coating and an increase in rate of melting by laser beam reduce coating wear resistance. Such rather complicated dependence of coating wear rate on conditions of laser melting and wearing process is due to a complex of structural and phase transformations which have contributed to formation of secondary solid inclusions and increased microhardness.Рассмотрены вопросы повышения физико-механических и эксплуатационных свойств клеевых покрытий после лазерного оплавления с дополнительным легированием В4С, ТаВ и МоВ. Изучено влияние лазерного оплавления с дополнительным легированием на структуру, микротвердость и износостойкость клеевых покрытий системы Fe–Cr–B –Si. С увеличением скорости лазерного луча микроструктура изменяется от равновесной до квазиэвтектической. Присутствие боридов молибдена и тантала повысило чувствительность покрытия к особенностям лазерного переплава. В обоих случаях изменились условия теплообмена, увеличилось количество боридов железа и хрома, в результате чего молибден и тантал частично перешли в свободное состояние, способствуя измельчению структурных составляющих. При введении твердых частиц B4C в покрытие происходит их растворение в матрице железа при нагреве лазерным лучом, при охлаждении они выделяются в виде отделенных включений боридов Fe и Cr. Лазерное оплавление и легирование повышают износостойкость покрытий. Увеличение нагрузки с 30 до 70 Н повышает износ покрытий в среднем на 15–26 %, а нелегированных покрытий – на 26–43 %. Повышение скорости оплавления и диаметра лазерного пятна не оказывает значительного влияния на износ, увеличение же коэффициента перекрытия приводит к снижению износа покрытия. Наличие твердых частиц ТаВ в покрытии и повышение скорости оплавления лучом лазера снижают износостойкость покрытия. Такая довольно сложная зависимость скорости износа покрытий от условий лазерного оплавления и износа обусловлена комплексом структурных и фазовых превращений, которые способствовали формированию вторичных твердых включений и повысили микротвердость