ART in Europe, 2016 : results generated from European registries by ESHRE

STUDY QUESTION: What are the reported data on cycles in ART, IUI and fertility preservation (FP) interventions in 2016 as compared to previous years, as well as the main trends over the years? SUMMARY ANSWER: The 20th ESHRE report on ART and IUI shows a progressive increase in reported treatment cycle numbers in Europe, with a decrease in the number of transfers with more than one embryo causing a reduction of multiple delivery rates (DR), as well as higher pregnancy rates and DR after frozen embryo replacement (FER) compared to fresh IVF and ICSI cycles, while the outcomes for IUI cycles remained stable. WHAT IS KNOWN ALREADY: Since 1997, ART aggregated data generated by national registries, clinics or professional societies have been collected, analysed by the European IVF-monitoring Consortium (EIM) and reported in 19 manuscripts published in Human Reproduction and Human Reproduction Open. STUDY DESIGN, SIZE, DURATION: Yearly collection of European medically assisted reproduction (MAR) data by EIM for ESHRE. The data on treatments performed between 1 January and 31 December 2016 in 40 European countries were provided by either National Registries or registries based on personal initiatives of medical associations and scientific organizations. PARTICIPANTS/MATERIALS, SETTING, METHODS: In all, 1347 clinics offering ART services in 40 countries reported a total of 918 159 treatment cycles, involving 156 002 with IVF, 407 222 with ICSI, 248 407 with FER, 27 069 with preimplantation genetic testing, 73 927 with egg donation (ED), 654 with IVM of oocytes and 4878 cycles with frozen oocyte replacement (FOR). European data on IUI using husband/partner’s semen (IUI-H) and donor semen (IUI-D) were reported from 1197 institutions offering IUI in 29 and 24 countries, respectively. A total of 162 948 treatments with IUI-H and 50 467 treatments with IUI-D were included. A total of 13 689 FP interventions from 11 countries including oocyte, ovarian tissue, semen and testicular tissue banking in pre-and postpubertal patients were reported. MAIN RESULTS AND THE ROLE OF CHANCE: In 20 countries (18 in 2015) with a total population of approximately 325 million inhabitants, in which all ART clinics reported to the registry, a total of 461 401 treatment cycles were performed, corresponding to a mean of 1410 cycles per million inhabitants (range 82–3088 per million inhabitants). In the 40 reporting countries, after IVF the clinical pregnancy rates (PR) per aspiration and per transfer in 2016 were similar to those observed in 2015 (28.0% and 34.8% vs 28.5% and 34.6%, respectively). After ICSI, the corresponding rates were also similar to those achieved in 2015 (25% and 33.2% vs 26.2% and 33.2%). After FER with own embryos, the PR per thawing is still on the rise, from 29.2% in 2015 to 30.9% in 2016. After ED, the PR per fresh embryo transfer was 49.4% (49.6% in 2015) and per FOR 43.6% (43.4% in 2015). In IVF and ICSI together, the trend towards the transfer of fewer embryos continues with the transfer of 1, 2, 3 and 4 embryos in 41.5%, 51.9%, 6.2% and 0.4% of all treatments, respectively (corresponding to 37.7%, 53.9%, 7.9% and 0.5% in 2015). This resulted in a proportion of singleton, twin and triplet DRs of 84.8%, 14.9% and 0.3%, respectively (compared to 83.1%, 16.5% and 0.4%, respectively in 2015). Treatments with FER in 2016 resulted in twin and triplet DR of 11.9% and 0.2%, respectively (vs 12.3% and 0.3% in 2015). After IUI, the DRs remained similar at 8.9% after IUI-H (7.8% in 2015) and at 12.4% after IUI-D (12.0% in 2015). Twin and triplet DRs after IUI-H were 8.8% and 0.3%, respectively (in 2015: 8.9% and 0.5%) and 7.7% and 0.4% after IUI-D (in 2015: 7.3% and 0.6%). The majority of FP interventions included the cryopreservation of ejaculated sperm (n¼7877 from 11 countries) and of oocytes (n¼4907 from eight countries). LIMITATIONS, REASONS FOR CAUTION: As the methods of data collection and levels of completeness of reported data vary among European countries, the results should be interpreted with caution. A number of countries failed to provide adequate data about the number of initiated cycles and deliveries. WIDER IMPLICATIONS OF THE FINDINGS: The 20th ESHRE report on ART and IUI shows a continuous increase of reported treatment numbers and MAR-derived livebirths in Europe. Being already the largest data collection on MAR in Europe, continuous efforts to stimulate data collection and reporting strive for future quality control of the data, transparency and vigilance in the field of reproductive medicine.The study has no external funding and all costs were covered by ESHRE.peer-reviewe

ART in Europe, 2017: results generated from European registries by ESHRE

© The Author(s) 2021. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.Study question: What are the data on ART and IUI cycles, and fertility preservation (FP) interventions reported in 2017 as compared to previous years, as well as the main trends over the years? Summary answer: The 21st ESHRE report on ART and IUI shows the continual increase in reported treatment cycle numbers in Europe, with a decrease in the proportion of transfers with more than one embryo causing an additional slight reduction of multiple delivery rates (DR) as well as higher pregnancy rates (PR) and DR after frozen embryo replacement (FER) compared to fresh IVF and ICSI cycles, while the number of IUI cycles increased and their outcomes remained stable. What is known already: Since 1997, ART aggregated data generated by national registries, clinics or professional societies have been gathered and analyzed by the European IVF-monitoring Consortium (EIM) and communicated in a total of 20 manuscripts published in Human Reproduction and Human Reproduction Open. Study design size duration: Data on European medically assisted reproduction (MAR) are collected by EIM for ESHRE on a yearly basis. The data on treatments performed between 1 January and 31 December 2017 in 39 European countries were provided by either National Registries or registries based on personal initiatives of medical associations and scientific organizations. Participants/materials setting methods: Overall, 1382 clinics offering ART services in 39 countries reported a total of 940 503 treatment cycles, including 165 379 with IVF, 391 379 with ICSI, 271 476 with FER, 37 303 with preimplantation genetic testing (PGT), 69 378 with egg donation (ED), 378 with IVM of oocytes, and 5210 cycles with frozen oocyte replacement (FOR). A total of 1273 institutions reported data on 207 196 IUI cycles using either husband/partner's semen (IUI-H; n = 155 794) or donor semen (IUI-D; n = 51 402) in 30 countries and 25 countries, respectively. Thirteen countries reported 18 888 interventions for FP, including oocyte, ovarian tissue, semen and testicular tissue banking in pre- and postpubertal patients. Main results and the role of chance: In 21 countries (20 in 2016) in which all ART clinics reported to the registry, 473 733 treatment cycles were registered for a total population of approximately 330 million inhabitants, allowing a best-estimate of a mean of 1435 cycles performed per million inhabitants (range: 723-3286).Amongst the 39 reporting countries, the clinical PR per aspiration and per transfer in 2017 were similar to those observed in 2016 (26.8% and 34.6% vs 28.0% and 34.8%, respectively). After ICSI the corresponding rates were also similar to those achieved in 2016 (24% and 33.5% vs 25% and 33.2% in 2016). When freeze all cycles were removed, the clinical PRs per aspiration were 30.8% and 27.5% for IVF and ICSI, respectively.After FER with embryos originating from own eggs the PR per thawing was 30.2%, which is comparable to 30.9% in 2016, and with embryos originating from donated eggs it was 41.1% (41% in 2016). After ED the PR per fresh embryo transfer was 49.2% (49.4% in 2016) and per FOR 43.3% (43.6% in 2016).In IVF and ICSI together, the trend towards the transfer of fewer embryos continues with the transfer of 1, 2, 3 and ≥4 embryos in 46.0%, 49.2%, 4.5% and in 0.3% of all treatments, respectively (corresponding to 41.5%, 51.9%. 6.2% and 0.4% in 2016). This resulted in a reduced proportion of twin DRs of 14.2% (14.9% in 2016) and stable triplet DR of 0.3%. Treatments with FER in 2017 resulted in a twin and triplet DR of 11.2% and 0.2%, respectively (vs 11.9% and 0.2% in 2016).After IUI, the DRs remained similar at 8.7% after IUI-H (8.9% in 2016) and at 12.4% after IUI-D (12.4.0% in 2016). Twin and triplet DRs after IUI-H were 8.1% and 0.3%, respectively (in 2016: 8.8% and 0.3%) and 6.9% and 0.2% after IUI-D (in 2016: 7.7% and 0.4%). Amongst 18 888 FP interventions in 13 countries, cryopreservation of ejaculated sperm (n = 11 112 vs 7877 from 11 countries in 2016) and of oocytes (n = 6588 vs 4907 from eight countries in 2016) were the most frequently reported. Limitations reasons for caution: As the methods of data collection and levels of reporting vary amongst European countries, interpretation of results should remain cautious. Some countries were unable to deliver data about the number of initiated cycles and deliveries. Wider implications of the findings: The 21st ESHRE report on ART, IUI and FP interventions shows a continuous increase of reported treatment numbers and MAR-derived livebirths in Europe. Being already the largest data collection on MAR in Europe, efforts should continue to optimize data collection and reporting with the perspective of improved quality control, transparency and vigilance in the field of reproductive medicine. Study funding/competing interests: The study has received no external funding and all costs are covered by ESHRE. There are no competing interests.info:eu-repo/semantics/publishedVersio

Oocyte and ovarian tissue cryopreservation in European countries : statutory background, practice, storage and use

STUDY QUESTION: What is known in Europe about the practice of oocyte cryopreservation (OoC), in terms of current statutory background, funding conditions, indications (medical and ‘non-medical’) and specific number of cycles? SUMMARY ANSWER: Laws and conditions for OoC vary in Europe, with just over half the responding countries providing this for medical reasons with state funding, and none providing funding for ‘non-medical’ OoC. WHAT IS ALREADY KNOWN: The practice of OoC is a well-established and increasing practice in some European countries, but data gathering on storage is not homogeneous, and still sparse for use. Ovarian tissue cryopreservation (OtC) is only practiced and registered in a few countries. STUDY DESIGN, SIZE, AND DURATION: A transversal collaborative survey on OoC and OtC, was designed, based on a country questionnaire containing information on statutory or professional background and practice, as well as available data on ovarian cell and tissue collection, storage and use. It was performed between January and September 2015. PARTICIPANTS/MATERIALS, SETTING AND METHODS: All ESHRE European IVF Monitoring (EIM) consortium national coordinators were contacted, as well as members of the ESHRE committee of national representatives, and sent a questionnaire. The form included national policy and practice details, whether through current existing law or code of practice, criteria for freezing (age, health status), availability of funding and the presence of a specific register. The questionnaire also included data on both the number of OoC cycles and cryopreserved oocytes per year between 2010 and 2014, specifically for egg donation, fertility preservation for medical disease, ‘other medical’ reasons as part of an ART cycle, as well as for ‘non-medical reasons’ or age-related fertility decline. Another question concerning data on freezing and use of ovarian tissue over 5 years was added and sent after receiving the initial questionnaire. MAIN RESULTS AND THE ROLE OF CHANCE: Out of 34 EIM members, we received answers regarding OoC regulations and funding conditions from 27, whilst 17 countries had recorded data for OoC, and 12 for OtC. The specific statutory framework for OoC and OtC varies from absent to a strict frame. A total of 34 705 OoC cycles were reported during the 5-year-period, with a continuous increase. However, the accurate description of numbers was concentrated on the year 2013 because it was the most complete. In 2013, a total of 9126 aspirations involving OoC were reported from 16 countries. Among the 8885 oocyte aspirations with fully available data, the majority or 5323 cycles (59.9%) was performed for egg donation, resulting in the highest yield per cycle, with an average of 10.4 oocytes frozen per cycle. OoC indication was ‘serious disease’ such as cancer in 10.9% of cycles, other medical indications as ‘part of an ART cycle’ in 16.1%, and a non-medical reason in 13.1%. With regard to the use of OoC, the number of specifically recorded frozen oocyte replacement (FOR) cycles performed in 2013 for all medical reasons was 14 times higher than the FOR for non-medical reasons, using, respectively, 8.0 and 8.4 oocytes per cycle. Finally, 12 countries recorded storage following OtC and only 7 recorded the number of grafted frozen/thawed tissues. LIMITATIONS, REASONS FOR CAUTION: Not all countries have data regarding OoC collection, and some data came from voluntary collaborating centres, rather than a national authority or register. Furthermore, the data related to use of OoC were not included for two major players in the field, Italy and Spain, where numbers were conflated for medical and non-medical reasons. Finally, the number of cycles started with no retrieval is not available. Data are even sparser for OtC. WIDER IMPLICATIONS OF THE FINDINGS: There is a need for ART authorities and professional bodies to record precise data for practice and use of OoC (and OtC), according to indications and usage, in order to reliably inform all stakeholders including women about the efficiency of both methods. Furthermore, professional societies should establish professional standards for access to and use of OoC and OtC, and give appropriate guidance to all involved. STUDY FUNDING/COMPETING INTEREST(S): The study was supported by ESHRE. There are no conflicts of interest.peer-reviewe

A picture of medically assisted reproduction activities during the COVID-19 pandemic in Europe

STUDY QUESTION: How did coronavirus disease 2019 (COVID-19) impact on medically assisted reproduction (MAR) services in Europe during the COVID-19 pandemic (March to May 2020)? SUMMARY ANSWER: MAR services, and hence treatments for infertile couples, were stopped in most European countries for a mean of 7 weeks. WHAT IS KNOWN ALREADY: With the outbreak of COVID-19 in Europe, non-urgent medical care was reduced by local authorities to preserve health resources and maintain social distancing. Furthermore, ESHRE and other societies recommended to postpone ART pregnancies as of 14 March 2020. STUDY DESIGN, SIZE, DURATION: A structured questionnaire was distributed in April among the ESHRE Committee of National Representatives, followed by further information collection through email. PARTICIPANTS/MATERIALS, SETTING, METHODS: The information was collected through the questionnaire and afterwards summarised and aligned with data from the European Centre for Disease Control on the number of COVID-19 cases per country. MAIN RESULTS AND THE ROLE OF CHANCE: By aligning the data for each country with respective epidemiological data, we show a large variation in the time and the phase in the epidemic in the curve when MAR/ART treatments were suspended and restarted. Similarly, the duration of interruption varied. Fertility preservation treatments and patient supportive care for patients remained available during the pandemic. LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Data collection was prone to misinterpretation of the questions and replies, and required further follow-up to check the accuracy. Some representatives reported that they, themselves, were not always aware of the situation throughout the country or reported difficulties with providing single generalised replies, for instance when there were regional differences within their country. WIDER IMPLICATIONS OF THE FINDINGS: The current article provides a basis for further research of the different strategies developed in response to the COVID-19 crisis. Such conclusions will be invaluable for health authorities and healthcare professionals with respect to future similar situations.peer-reviewe

ART in Europe, 2019 : results generated from European registries by ESHRE

Study question: What are the data and trends on ART and IUI cycle numbers and their outcomes, and on fertility preservation (FP) interventions, reported in 2019 as compared to previous years? Summary answer: The 23rd ESHRE report highlights the rising ART treatment cycles and children born, alongside a decline in twin deliveries owing to decreasing multiple embryo transfers; fresh IVF or ICSI cycles exhibited higher delivery rates, whereas frozen embryo transfers (FET) showed higher pregnancy rates (PRs), and reported IUI cycles decreased while maintaining stable outcomes. What is known already: ART aggregated data generated by national registries, clinics, or professional societies have been gathered and analyzed by the European IVF-Monitoring (EIM) Consortium since 1997 and reported in a total of 22 manuscripts published in Human Reproduction and Human Reproduction Open. Study design, size, duration: Data on medically assisted reproduction (MAR) from European countries are collected by EIM for ESHRE each year. The data on treatment cycles performed between 1 January and 31 December 2019 were provided by either national registries or registries based on initiatives of medical associations and scientific organizations or committed persons in one of the 44 countries that are members of the EIM Consortium. Participants/materials, setting, methods: Overall, 1487 clinics offering ART services in 40 countries reported, for the second time, a total of more than 1 million (1 077 813) treatment cycles, including 160 782 with IVF, 427 980 with ICSI, 335 744 with FET, 64 089 with preimplantation genetic testing (PGT), 82 373 with egg donation (ED), 546 with IVM of oocytes, and 6299 cycles with frozen oocyte replacement (FOR). A total of 1169 institutions reported data on IUI cycles using either husband/partner's semen (IUI-H; n = 147 711) or donor semen (IUI-D; n = 51 651) in 33 and 24 countries, respectively. Eighteen countries reported 24 139 interventions in pre- and post-pubertal patients for FP, including oocyte, ovarian tissue, semen, and testicular tissue banking. Main results and the role of chance: In 21 countries (21 in 2018) in which all ART clinics reported to the registry 476 760 treatment cycles were registered for a total population of approximately 300 million inhabitants, allowing the best estimate of a mean of 1581 cycles performed per million inhabitants (range: 437-3621). Among the reporting countries, for IVF the clinical PRs per aspiration slightly decreased while they remained similar per transfer compared to 2018 (21.8% and 34.6% versus 25.5% and 34.1%, respectively). In ICSI, the corresponding PRs showed similar trends compared to 2018 (20.2% and 33.5%, versus 22.5% and 32.1%) When freeze-all cycles were not considered for the calculations, the clinical PRs per aspiration were 28.5% (28.8% in 2018) and 26.2% (27.3% in 2018) for IVF and ICSI, respectively. After FET with embryos originating from own eggs, the PR per thawing was at 35.1% (versus 33.4% in 2018), and with embryos originating from donated eggs at 43.0% (41.8% in 2018). After ED, the PR per fresh embryo transfer was 50.5% (49.6% in 2018) and per FOR 44.8% (44.9% in 2018). In IVF and ICSI together, the trend toward the transfer of fewer embryos continues with the transfer of 1, 2, 3, and ≥4 embryos in 55.4%, 39.9%, 2.6%, and 0.2% of all treatments, respectively (corresponding to 50.7%, 45.1%, 3.9%, and 0.3% in 2018). This resulted in a reduced proportion of twin delivery rates (DRs) of 11.9% (12.4% in 2018) and a similar triplet DR of 0.3%. Treatments with FET in 2019 resulted in twin and triplet DR of 8.9% and 0.1%, respectively (versus 9.4% and 0.1% in 2018). After IUI, the DRs remained similar at 8.7% after IUI-H (8.8% in 2018) and at 12.1% after IUI-D (12.6% in 2018). Twin and triplet DRs after IUI-H were 8.7% and 0.4% (in 2018: 8.4% and 0.3%) and 6.2% and 0.2% after IUI-D (in 2018: 6.4% and 0.2%), respectively. Eighteen countries (16 in 2018) provided data on FP in a total number of 24 139 interventions (20 994 in 2018). Cryopreservation of ejaculated sperm (n = 11 592 versus n = 10 503 in 2018) and cryopreservation of oocytes (n = 10 784 versus n = 9123 in 2018) were most frequently reported. Limitations, reasons for caution: Caution with the interpretation of results should remain as data collection systems and completeness of reporting vary among European countries. Some countries were unable to deliver data about the number of initiated cycles and/or deliveries. Wider implications of the findings: The 23rd ESHRE data collection on ART, IUI, and FP interventions shows a continuous increase of reported treatment numbers and MAR-derived livebirths in Europe. Although it is the largest data collection on MAR in Europe, further efforts toward optimization of both the collection and the reporting, from the perspective of improving surveillance and vigilance in the field of reproductive medicine, are awaited. Study funding/competing interest(s): The study has received no external funding and all costs are covered by ESHRE. There are no competing interests. Keywords: ICSI; IUI; IVF; data collection; egg donation; fertility preservation; frozen embryo transfer; registry; surveillance; vigilance.peer-reviewe

Исследование причин возникновения выщербин металла на поверхности катания железнодорожных колес

Грищенко, М. А. Дослідження причин виникнення вищербин металу на повехні кочення залізничних коліс / М. А. Грищенко // Вісник Дніпропетровського національного університету залізничного транспорту імені академіка В. Лазаряна. - Д., 2008. - Вип. 23. - С. 178-182. УДК 669.14.018,294UK: У статті наведено результати досліджень стосовно виникнення дефектів – вищербин металу по поверхні кочення залізничних коліс.RU: В статьи приведены результаты исследований относительно возникновения дефектов – выкрашивания металла по поверхности качения железнодорожных колес.EN: In the article the research results related to an origin of defects – crumbling out of metal on the tread contact surface of railway wheels – are presented

Процесс формирования повреждений железнодорожных колес и бандажей при эксплуатации

Grischenko, N. A. The process of formation of railway wheel damages and tires in operation / N. A. Grischenko // Наука та прогрес транспорту. — 2015. — № 1 (55). — С. 100—112. — Библиогр. в конце ст. — doi: 10.15802/stp2015/38252EN: Purpose. The dependence analysis of structural changes in the metal of railway wheels and tires from indicated influences in operation, for the further development of strategy of service reliability growth. Methodology. Test materials are the details selected from railway wheels which were taken out of operation beforehand because of various damages. Micro-structural researches were made with the use of light microscope Epiquant and electron microscope. The sizing of structural elements was done by using the methods of quantitative metallography. Findings. Over the past few decades the rapid development of industry was supported by the steady growth of intensity of using railway transport. In this case simultaneous increase of load at wheel set axle, with the increase of speed was accompanied by natural increase of the amount of cases of premature wheels and tires’ withdrawing out of operation. Railway wheel, except the formation of metal layer at rolling surface with the high defects concentration of crystal structure and first of all dislocations, falls under thermal influence from interaction with break blocks. The nature of joint influence (cold deformation and heating) on the metal rim of a wheel is conditioned by the appearance of sufficiently high gradients of structural changes that can be considered as the influence on the level of internal residual stresses. In case of the rise of volume part of carbide phase at a constant ferrite grain size, it is achieved only by the increasing of dislocation nucleation sources without changing the number of annihilation positions. In this case the accumulation of dislocations at the initial stages of plastic deformation (in metal volume in front of delta arm crack) will lead to the formation of cementite globes around certain interlocked dislocation density. In contrast the sharp increase of deformation hardening carbon steel parameters is observed. Originality. During the braking of locomotive the speed rise of metal heating at rolling surface is provided with the increase of temperatures that is enough for the beginning of phase transformations. Under the further cooling there is the formation of a number of structures formed from sliding to diffusive mechanisms. As a result the chosen areas become the centers of future metal deformations on wheels’ rolling surface and tires. Practical value. Based on the study of patterns of damages’ formation in railway wheels and tires from the peculiarities of internal metal structure and the working conditions «Classifier of defects» was developed аnd «Technical tips for determination of causes of cracks in solid-rolled railway wheels and destruction in general», which have been implemented on Ukrzaliznytsia.UK: Мета. У роботі необхідно провести аналіз залежності структурних перетворень у металі залізничних коліс та бандажів від визначених впливів при експлуатації, для подальшої розробки концепції підвищення їх експлуатаційної надійності. Методика. Матеріал для досліджень – фрагменти, відібрані від залізничних коліс, які, в свою чергу, попередчасно, за рахунок різноманітних ушкоджень, були вилучені з експлуатації. Мікроструктурні дослідження проводили з використанням світлового мікроскопа Epiquant та електронного мікроскопа. Оцінку розміру структурних елементів проводили, використовуючи методики кількісної металографії. Результати. В останні десятиріччя прискорений розвиток промисловості супроводжувався неухильним зростанням інтенсивності експлуатації залізничного транспорту. При цьому одночасне підвищення навантаження на вісь колісної пари, разом із зростанням швидкості руху, супроводжувалося закономірним збільшенням кількості випадків передчасного вилучення коліс і бандажів із експлуатації. Залізничне колесо, окрім формування прошарку метала по поверхні кочення з високою концентрацією дефектів кристалічної будови і, в першу чергу, дислокацій, піддається температурному впливу від взаємодії з гальмівними колодками. Характер сумісного впливу (холодне деформування й розігрів) на метал ободу колеса обумовлює виникнення достатньо високих градієнтів структурних змін, що, в свою чергу, може розглядатися, як вплив на рівень внутрішніх остаточних напружень. При підвищенні об’ємної частки карбідної фази, при незмінному розмірі зерна фериту, досягається лише збільшення джерел зародження дислокацій, без зміни кількості місць анігіляції. В цьому випадку накопичення дислокацій вже на початкових етапах пластичної деформації (в об’ємах металу попереду гирла тріщини) призведе до формування навколо глобулів цементиту визначеної щільності взаємозаблокованих дислокацій. На підставі цього спостерігається різке підвищення параметрів деформаційного зміцнення вуглецевої сталі. Наукова новизна. В процесі гальмування рухомого складу підвищення швидкості розігріву металу на поверхні кочення супроводжується зростанням температур, достатніх до початку фазових перетворень. При подальшому охолодженні відбувається поява низки структур, сформованих від зсувного до дифузійного механізмів. Внаслідок цього, вказані ділянки стають осередками майбутніх руйнувань металу на поверхні кочення коліс і бандажів. Практична значимість. На основі вивчення закономірностей формування ушкоджень у залізничних колесах та бандажах від особливостей внутрішньої будови металу та умов експлуатації розроблено «Класифікатор дефектів» та «Методичні вказівки з порядку визначення причин виникнення тріщин в суцільнокатаних колесах та руйнування в цілому», котрі впроваджено на Укрзалізниці.RU: Цель. В работе необходимо провести анализ зависимости структурных превращений в металле железнодорожных колес и бандажей от определенных воздействий при эксплуатации, для дальнейшей разработки концепции повышения их эксплуатационной надежности. Материал и методика исследований. Методика. Материал для исследований – фрагменты, отобранные из железнодорожных колес, которые, в свою очередь, преждевременно, за счет различных повреждений, были изъяты из эксплуатации. Микроструктурные исследования проводили с использованием светового микроскопа Epiquant. и электронного микроскопа. Оценку размера структурных элементов проводили, используя методики количественной металлографии. Результаты. В последние десятилетия ускоренное развитие промышленности сопровождалось неуклонным ростом интенсивности эксплуатации железнодорожного транспорта. При этом одновременное повышение нагрузки на ось колесной пары, вместе с ростом скорости движения, сопровождалось закономерным увеличением количества случаев преждевременного изъятия колес и бандажей из эксплуатации. Железнодорожное колесо, кроме формирования прослойки металла по поверхности катания с высокой концентрацией дефектов кристаллического строения и, в первую очередь, дислокаций, подвергается температурному воздействию от взаимодействия с тормозными колодками. Характер совместного влияния (холодное деформирование и разогрев) на металл обода колеса обуславливает возникновение достаточно высоких градиентов структурных изменений, что, в свою очередь, может рассматриваться как влияние на уровень внутренних окончательных напряжений. При повышении объемной доли карбидной фазы, при неизменном размере зерна феррита достигается только увеличение источников зарождения дислокаций, без изменения количества мест аннигиляции. В этом случае накопления дислокаций уже на начальных этапах пластической деформации (в объемах металла впереди устья трещины) приведет к формированию вокруг глобулы цементита определенной плотности заблокированных дислокаций. На основании этого наблюдается резкое повышение параметров деформационного упрочнения углеродистой стали. Научная новизна. В процессе торможения подвижного состава повышение скорости разогрева металла на поверхности катания сопровождается ростом температур, достаточных для начала фазовых превращений. При дальнейшем охлаждении происходит появление ряда структур, сформированных от сдвижного к диффузионному механизмам. Вследствие этого, указанные участки становятся очагами будущих разрушений металла на поверхности катания колес и бандажей. Практическая значимость. На основе изучения закономерностей формирования повреждений в железнодорожных колесах и бандажах от особенностей внутреннего строения металла и условий эксплуатации разработаны «Классификатор дефектов» и «Методические указания по порядку определения причин возникновения трещин в цельнокатаных колесах и разрушения в целом», внедренные на Укрзализныце

Систематизация дефектов железнодорожных колес

Грищенко, М. А. Систематизація дефектів залізничних коліс / М. А. Грищенко // Вісник Дніпропетровського національного університету залізничного транспорту імені академіка В. Лазаряна. - Д., 2008. - Вип. 24. - С. 199-200. УДК 621.771.23.016.3.01UK: У статті наведені результати досліджень появи дефектів у залізничник колесах, систематизація та спроба пояснення причин їх виникнення.RU: В статье приведены результаты исследований появления дефектов в железнодорожных колесах, систематизация и попытка объяснения причин их появления.EN: In the article the research results of occurring defects in railroad wheels, the systematization and attempt of explaining the causes of occurring them are presented

An increase of operating safety elements wheelpairs is on the basis of determination mechanisms forming defects

Грищенко , М. А. Підвищення експлуатаційної безпеки елементів колісних пар на основі визначення механізмів формування дефектів : автореф. дис. ... канд. техн. наук: 05.22.20 / М. А. Грищенко ; Дніпропетр. нац. ун-т залізн. трансп. ім. акад. В. Лазаряна. - Дніпропетровськ., 2015. - 21 с. УДК 629.4.027.5:620.19(043.3) Захист - 22 жовтня 2015 р.UK: Дисертаційна робота присвячена встановленню закономірностей зміни структурного стану, механічних властивостей сталей залізничних коліс, локомотивних бандажів та вісей колісних пар залежно від умов експлуатації та технології виготовлення. Досліджено хімічні, механічні властивості вуглецевих сталей для виготовлення коліс, бандажів та вісей. Базуючись на методи й методики, стало можливим оцінити зміну внутрішньої будови сталей залізничних коліс, бандажів та вісей в залежності від ступеня зовнішніх впливань, які можуть сприяти зародженню ушкоджень.Визначено, що мікротріщина, яка зароджена на міжфазній межі неметалеве включення-феритна складова структури вуглецевої сталі, розповсюджується у напрямку локально зниженого опору металу. Підвищення локалізації пластичної течії вуглецевої сталі при збільшенні розміру зерна фериту являє собою один із чинників, який знижує межу міцності при втомі. Проведений аналіз зміни внутрішньої будови вуглецевих сталей з урахуванням ступеня розігріву від поверхні кочення показав, що пропорційно градієнту температур виникають внутрішні напруження, які в місцях з низьким опором металу приводять до формування зародків руйнування. Враховуючи, що протікання втомних явищ в металі обумовлене незворотними структурними змінами, такими як поступове накопичення дефектів кристалічної будови, можливість зниження їх приросту дозволить підвищити ресурс роботи елементів рухомого складу.RU: Диссертационная работа посвящена установлению закономерностей изменения структурного состояния, механических свойств сталей железнодорожных колес, локомотивных бандажей и осей колесных пар в зависимости от условий эксплуатации и технологии изготовления. Исследованы химические, механические свойства углеродных сталей для изготовления колес, бандажей и осей. Базируясь на методы и методики, стало возможным оценить изменение внутреннего строения сталей железнодорожных колес, бандажей и осей в зависимости от степени внешних влияний, которые могут способствовать зарождению повреждений. Определено, что микротрещина, которая зарождена на межфазном границе неметаллическое включение-ферритная составляющая структуры углеродной стали, распространяется в направлении локально сниженного сопротивления металла. Повышение локализации пластического течения углеродной стали при увеличении размера зерна феррита являет собой один из факторов, который снижает предел прочности при усталости. Рост предела прочности при усталости колесных сталей при увеличении дисперсности перлитной колонии обусловлен увеличением отношения критического раскрытия растущей трещины к межкарбидному расстоянию. Проведенный анализ изменения внутреннего строения углеродных сталей с учетом степени разогрева от поверхности качения показал, что пропорционально градиенту температур возникают внутренние напряжения, которые в местах с низким сопротивлением металла приводят к формирования зародышей разрушения. На основании изучения случаев преждевременно изъятия железнодорожных колес из эксплуатации определено, что наиболее частой причиной формирования дефектов, является развитие процессов контактной усталости металла. Учитывая, что протекание усталостных явлений в металле обусловлено необратимыми структурными изменениями, такими как постепенное накопление дефектов кристаллического строения, возможность снижения их прироста позволит повысить ресурс работы элементов подвижного состава. В подавляющем большинстве разрушение обода обусловлено формированием усталостных трещин разного происхождения (циклическое изменение действующих напряжений в элементах колеса, температурные влияния и др.). Предложенная методика определения периодичности контроля профиля бандажа и проведении ремонта будет способствовать его рациональному использованию, повышая ресурс работы и эксплуатационную безопасность.EN: Dissertation work is devoted establishment of conformities to the law of change of the structural state, mechanical properties steels of railway wheels, locomotive bracers, ax of wheelpairs depending on external and technology of making environments. The chemical, mechanical properties of carbon steel for the manufacture of wheels, tires and axles. Based on methods and techniques, it was possible to evaluate the change in internal structure of steel railway wheels, tires and axles depending on the external vplyvan that may contribute to birth injuries. Determined that the cracks that born-interfaces on the verge of non-metallic inclusion, ferrite component structure of carbon steel, extends towards the local low resistance metal. Increasing localization of plastic flow of carbon steel with increasing ferrite grain size is one of the factors that limit reduces fatigue strength. The analysis of changes in the internal structure of carbon steel based on heating degree roll surface showed that the proportion temperature gradient arising internal stresses that in places with low resistance metal lead to the formation of embryos destruction. Whereas the occurrence of fatigue phenomena in metals caused irreversible structural changes, such as the gradual accumulation of defects in the crystal structure, the ability to reduce their growth will increase the life of the items of rolling stock

The Definition of Material Deformation Strengthening in the Volume of Individual Grains of Polycrystals

Вакуленко, Л. І. Визначення параметрів деформаційного зміцнення в об'ємах окремих зерен полікристалів / Л. І. Вакуленко, М. А. Грищенко // Вісн. Дніпропетр. нац. ун-ту залізн. трансп. ім. акад. В. Лазаряна. — Днепропетровск, 2008. — Вип. 25. С. 204—206. УДК 669.14 – 157.97UK: Розглянуті питання оцінки мікротвердості при зміні навантаження на індентор при навантаженнях в одне і те ж місце зразка.EN: The questions of microhardness estimate in changing the loading on indenter, if the same place of a sample is loaded, are considered.RU: Рассмотрены вопросы оценки микротвердости при изменении загрузки на индентор при условиях нагружения в одно и то же место образца