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Surface microrelief and hardness of laser hardened and ultrasonically peened AISI D2 tool steel
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This paper is focused on experimental analysis of the effects of laser surface hardening (LSH) combined with subsequent ultrasonic impact treatment (UIT) on the surface microrelief, hardness and microstructure in near-surface layers of AISI D2 high-chromium, cold worked tool steel. The LSH provides fast heating of the near-surface layers to the temperature above that of the phase transformation and temperature then rapidly cools by a self-quenching process. The formed heat affected zone is hardened thanks to the rapid heating/cooling process affecting microstructure, phase composition and carbides formation. Conversely, the UIT induces multiple impact loads providing severe plastic deformation of near-surface layers, and the hardening occurs by a dislocations mediated process. The optimal parameters of each process were determined to obtain maximum hardness and regular surface microrelief. Further, complete analysis of the effect of combined treatment (LSH+UIT) on the surface hardness, microhardness depth profile and surface microrelief was performed. Results show that the combined LSH+UIT process provides almost triple, double and a 10% increase in hardness in comparison with those of the initial, UIT-processed and LSH-treated states, respectively. The surface microrelief, waviness and roughness parameters were respectively diminished after LSH+UIT by approx. 50, 65, and 90%. XRD analysis was carried out after LSH and LSH+UIT processes, which showed essential α-Fe peaks broadening due to the formation of microstrains (0.27% and 0.47%, respectively) and reduction in crystallite size (84 nm after LSH+UIT). Favorable compressive residual stresses (–205 MPa and –409 MPa, respectively) were also observed in the near-surface layers of ~350 and 80 μm thick, respectively. The obtained results demonstrate that combined LSH+UIT process is feasible surface treatment for the quality improvement of the tool steel components including both the surface microrelief and hardness characteristics.
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... However, it should be noted that the melting of the surface layer caused a complex distribution of residual macrostresses on the surface [23]. On the other hand, the hardened surface must be subjected to severe surface-plastic deformation to improve the surface roughness and induce residual compressive stresses [24,25]. ...
... Prior to the LHT treatment, on the one hand, the LHT modes were selected based on the data obtained by the laser surface hardening according to the strategy of constant temperature [24]. On the other hand, the temperature distribution analysis was performed both at the depth and on the surface of the processed specimen in a single-pass laser transformation hardening using a thermo-physical model [25]. ...
... The scanner-based LHT-hardened second track contains a fine-grained/lath martensite and residual austenite for the AISI 1045 steel (Fig. 9) and martensite, Cr 7 C 3 and Cr 23 C 6 carbides dispersed in the iron matrix, and residual austenite for the AISI D2 steel (Fig. 10) in the transformation hardening area. The volume fraction of the Fig. 8 Microhardness distribution in the sample cross-section of the AISI D2 steel along longitudinal directions at the overlapping ratio of 10% (a), 25% (b), and 40% (c) at different hardness loads retained austenite in the laser-hardened layer did not exceed 5% for the carbon steel [5] and 10% for the tool steel [24]. Yao et. ...
The study and prediction of the structure and hardness in the overlapping area during multi-pass laser heat treatment (LHT) is an important issue for the preparation of the technological process and directly affects the choice of the LHT parameters. The scanner-based laser transformation hardening of the AISI 1045 medium carbon steel and AISI D2 high-chromium tool steel was carried out in a continuous mode using a Rofin Sinar FL010 fiber laser and two-dimensional (2D) optical system. The laser multi-tracks with an overlapping scanning beam of 10%, 25%, and 40% were produced. The computer numerical control programs for the scanner-based laser surface hardening of the large-scale metal parts with various overlapping ratios were developed. The experimental results of the overlapping depth and hardness were compared with the heat-affected zone geometry and Vickers hardness measurements. The microstructure in the laser-hardened and laser-tempered areas is studied by optical microscopy. It was revealed that the overlapping ratio should be selected at 20–25% to obtain the overlapping depth of ~ 400 µm for the studied steels. Unlike carbon steel, the required surface hardness is provided in the laser-tempered zone of the tool steel. To increase the surface hardness in the laser-overlapped area, a multi-pin ultrasonic impact treatment was additionally applied. The results indicated that the severe surface plastic deformation provides the required microhardness in the overlapping area for the AISI 1045 carbon steel.
... 2. Сучасне ультра звукове обладнання та змінні ударні головки З КАФЕДРИ ПРЕЗИДІЇ НАН УКРАЇНИ ції структурно-фазового стану металів і сплавів із застосуванням широкого кола поверхнево чутливих методів аналізу, які дозволяють отримувати інформацію на атомно-молекулярному рівні про будову найтонших поверхневих шарів (завтовшки кілька нанометрів), у комплексі з мікроскопічними методами, що дають картину структурно-фазових перебудов у процесі модифікації поверхневих шарів мікронної товщини. Встановлено фізичні мікромеханізми структурних перебудов та формування нанорозмірних, ультрадисперсних і градієнтних зеренних структур [7,13,14,[60][61][62][63], а також нано-і мікрокомпозитів та шаруватих структур в ударно деформованих поверхневих шарах [64][65][66][67][68][69]. ...
... Така шарувата структура повторює будову кістки, тому перспективним є використання цього матеріалу для імплантів з високою біомеханічною сумісністю з тканинами людського організму (низький модуль пружності, високі корозійна стійкість і втомна довговічність) [78,82]. Високу ефективність щодо підвищення зносостійкості та корозійної стійкості сталей різного класу показали комбіновані методи модифікування поверхні із залученням електроіскрового легування [28,30,67] або лазерної термічної дії [35,39,[61][62][63] та фінішної УЗУО. ...
... Досліджено кореляцію між структурно-фазовим станом, твердістю і зносостійкістю поверхні конструкційних (сталь 45) [40,61] та Рис. 3. Схема шаруватої структури кістки та поруватого титанового матеріалу після УЗУО, придатного для біомедичного застосування; ТЕМ-і РЕМ-зображення структури його поверхневого (а, б) та проміжного (в, г, д) шарів і поруватої серцевини (e) m m З КАФЕДРИ ПРЕЗИДІЇ НАН УКРАЇНИ інструментальних (Х12МФ, 9Г2Ф) [39,41,63] сталей після лазерного термозміцнення і комбінованої лазерної обробки (ЛО) та УЗУО. В інструментальних сталях спостережуване збільшення твердості зумовлене, відповідно, нанодвійниками (ЛО), щільними дислокаційними сітками (УЗУО) та дислокаційними комірками/нанозернами, зафіксованими дисперсними карбідами (ЛО + УЗУО), що утворюються в поверхневих шарах сталі. ...
У доповіді наведено аналіз ефективності методу високочастотного ударного проковування ультразвуковим інструментом (УЗУО, або ВМП). Розглянуто механізми формування нанорозмірних зеренних структур і композитів, перерозподілу напружень, можливості усунення дефектів і поруватості в поверхневих шарах металевих матеріалів, отриманих за допомогою традиційних і новітніх адитивних технологій 3D-друку і призначених для виробництва зварних конструкцій і споруд, а також методології ультразвукових прецизійних вимірювань і неруйнівного контролю. Окреслено перспективи впровадження цих методів у транспортному машинобудуванні та медицині для забезпечення підвищеного ресурсу, опору втомі, корозії та зношуванню.
... Currently, both traditional and advanced highly concentrated surface treatment methods are used to form the required material properties for the fatigue and corrosion/wear resistance of metal components. One of the most effective solutions is the application of the laser surface modification techniques in combination with advanced mechanical surface treatments to enhance the surface characteristics [1][2][3]. The combination of individual types of modification techniques allows obtaining a much greater effect in increasing the surface characteristics of metal parts to prolong their operation life. ...
... Fig. 1, d illustrates a schematic diagram of the multi-pin impact head. The multi-pin UIP system is described in detail [3,22,23]. The UIP experiments are carried out at a vibration frequency f UIP of 21.6 kHz and amplitude AUIP of ultrasonic horn tip of 15 µm. ...
... This is because of the rotated multi-pin head which provides the sliding impact of seven pins by the sample surface. This result also correlates well with the literature data [3,8]. Moreover, as compared to the combined LSP + WjCP and LSP + WjSP techniques, the combined LSP + UIP technique forms a regular microrelief with lower roughness parameters due to the application of the multi-pin ultrason- ic tool which moved by a Computer Numerical Control (CNC) program and rotated forcedly by a motor. ...
... DED-HT D2 material showed values of 1794 ± 69 MPa (UTS), 1480 ± 43 MPa (YS), and 0.8 ± 0.1% (elongation) (Fig. 10 (a)). Comparison of conventional wrought AISI D2 and tensile properties showed the UTS and YS values of DED-built D2 material to be higher than those of annealed wrought AISI D2 [52,53], and DED-HT showed similar UTS and YS values to heat-treated wrought AISI D2 [49,50,54]. As for the elongation, both DED-built D2 and DED-HT D2 showed slightly lower values when compared to annealed [52,53] and heat-treated [50,54] wrought AISI D2 materials. ...
... Comparison of conventional wrought AISI D2 and tensile properties showed the UTS and YS values of DED-built D2 material to be higher than those of annealed wrought AISI D2 [52,53], and DED-HT showed similar UTS and YS values to heat-treated wrought AISI D2 [49,50,54]. As for the elongation, both DED-built D2 and DED-HT D2 showed slightly lower values when compared to annealed [52,53] and heat-treated [50,54] wrought AISI D2 materials. ...
This study investigated the microstructure and tensile properties of AISI D2 tool steel manufactured by direct energy deposition (DED). The effect of standard post-heat treatment on the mechanical properties and deformation behavior of DED AISI D2 was also examined. The as-built AISI D2 manufactured through the DED process showed the eutectic structure in the interdendrite area in addition to dendrites about 4–5 μm wide. After heat treatment, the carbides in eutectic lamellar structure were transformed into the network and needle type secondary carbides. The DED-built material was interestingly composed of austenite, which transformed into martensite after heat treatment. Hardness value for DED-built material was 486.2 ± 10.6 HV, while for heat-treated material the value was 720.1 ± 10.0 HV. Furthermore, post heat treatment led to tremendous increases in yield strength (784 ± 7.7 MPa to 1480 ± 43.0 MPa) and tensile strength (1054 ± 2 MPa to 1794 ± 69.0 MPa). The hardness value, yield and tensile strengths for DED-built AISI D2 were similar to those of heat-treated conventional wrought AISI D2. In addition, brittle fractures were observed in the tensile fracture surfaces regardless of whether heat treatment was applied. In particular, tensile deformed specimen before heat treatment showed deformation-induced martensite transformation in the areas close to the eutectic structures, while after heat treatment interdendritic cracking as well as transdendritic cracking within the matrix were mainly detected. Based on the above results, the deformation behavior and fracture mechanism of AISI D2 manufactured by direct energy deposition were also discussed.
... Ultrasonic impact treatment is one of the most efficient and affordable high-productivity methods for improving the mechanical properties of metals and alloys by texturing surfaces with complex geometries without changing their chemical composition. Numerous researchers in the field of UIT have produced surfaces of various metallic materials, including steel, copper, aluminium, titanium, and their alloys, that are textured with micro-dimples [11,[34][35][36][37][38][39][40]. Morphological control of surfaces treated by UIT (the texture and size of micro-dimples, its surface density) is mainly realised by scanning electron microscopy (SEM) and atomic force microscopy (AFM), along with three-dimensional optical profilometry. ...
... To the best of our knowledge, there have been no investigations on the UIT (or UNSM-assisted) oxidation behaviour of stainless steels. At the same time, in several works [36,70] it was reported that modification of AISI D2 tool steel by UIT does not lead to oxide formation on the treated surface. Moreover, laser heat treatment (LHT) with subsequent UIT provides fragmentation and removal of the oxide film on the AISI D2 steel surface that formed during LSH, as well as on the surface of AISI 1045 medium-carbon steel [71]. ...
This work reports the appearance of iridescent spectral patterns in the form of coloured stripes on AISI 321 steel surfaces subjected to ultrasonic impact treatment (UIT). The possible reasons for the UIT-textured surface coloration are considered from the viewpoints of wave (diffraction and interference) optics. According to the XRD analysis, the phase composition of the AISI 321 steel surface layer after UIT is represented by the austenite and martensite iron phases. The chemical composition of the UIT-textured steel near-surface layer is identified using XPS, which includes iron and chromium in the oxidised and metallic states. The thickness of the oxygen-enriched layer after UIT is estimated to be approximately 15 nm. SEM and AFM analysis confirmed that UIT provides the formation of periodic surface structures with characteristic dimensions from several hundreds of nanometres to several micrometres coinciding in order of magnitude with wavelengths in the visible range. Applying different processing modes of AISI 321 steel surface leads to qualitative transformations in the spectral patterns: the position of the coloured stripes, its width, and the total number of the observed diffraction maxima change according to the equation of light diffraction. The obtained results indicate that diffraction of light is the main reason for the appearance of spectral patterns on the UIT-textured AISI 321 steel surface, which is analogous to a reflective diffraction grating. Structural diffraction coloration could be used as a possible basis for a non-destructive spectral control for UIT-textured steel surfaces and indirect monitoring of the performance of UIT equipment.
... Aluminum alloys compared with ferrous alloys have high specific heat, heat conductivity and reflectivity to laser power density, controlling laser parameters like power density, irradiated time, speed of scanning plays major role in solidification thus the microstructure in the surface can be changed according to the need. Several methods are employed to improve corrosion resistance of aluminum alloys but laser surface melting yielded better results, it improves local- ized resistance to corrosion because of homogeneity, refinement in grains and phase transformations [39,41]. ...
... The investigation on the microhardness and gradient of laser hardened AISI 1045 carbon steel using response surface methodology was carried out by Chen et al. [19]. Lesyk et al. [20] developed a compound surface treatment approach of laser surface hardening and ultrasonic impact treatment and examined the influences of D2 die steel on surface morphology, hardness, and microstructure. Li et al. [21] compared the effects of laser hardening of AISI 1045 steel applying CO 2 laser and high-power diode laser. ...
Although a laser beam with a small diameter (< 1 mm) can significantly improve surface morphology, the polishing efficiency is very low, and the improvement of surface hardness is negligible. In this work, a novel laser polishing-hardening (LPH) method with integration and high efficiency for the treatment of AISI D2 tool steel using a large-size laser beam (Φ2.8 mm) was proposed, and the effects of laser hardening (LH), laser polishing (LP), and LPH treatments on the surface topography and microhardness were examined. The results show that the LH method had a negligible effect on the surface roughness of the treated sample, while the surface roughness Ra of LP and LPH specimens was reduced by 74.6% and 80.9%, respectively, indicating that the milled surface topography had been significantly improved, especially LPH was more effective in reducing the roughness. Besides, the polishing efficiency of LPH was 10 times that of the LP approach. In terms of hardness improvement, the near-surface microhardness of LH and LPH samples increased by 1.5 times and 1.3 times, respectively, and the effective hardened zone (EHZ) depth was 0.42 mm and 0.24 mm, respectively, demonstrating that these two laser processing methods had a beneficial effect on the cross-section microhardness of D2 tool steel, while the increase of LP on the microhardness was insignificant. The comprehensive analysis of the surface morphology and microhardness of the LPH specimen indicates that LPH was a feasible laser surface treatment method for D2 tool steel. On the premise of ensuring a high surface finish, the polishing efficiency can be remarkably improved, and the subsurface microhardness and EHZ depth of processed specimen can be also significantly increased, which provided a feasible idea for the application of laser surface treatment technology in industrial mold production.
Titanium (Ti) and its alloy implants with porous structure manufactured by selective laser melting (SLM) can match elastic modulus of human bone to reduce the stress‐shielding effect and satisfy the personalized requirement in orthopedic surgery. Compared with conventional casting and forging Ti and its alloy implants, SLM implants possess unique microstructural features and excellent comprehensive mechanical properties. However, the un‐melted powder particles inevitably adhere to the surfaces of SLM implants, which may result in excessive surface roughness and potential health risks. Moreover, there are significant issues encountered, such as bioactivity, toxicity, antibacterial activity, corrosion and wear resistance. Consequently, surface modification methods are essential to remove the un‐melted powder particles and improve biological and mechanical properties of SLM implants. Herein, the research efforts focus exclusively on chemical (acid treatment, alkali treatment, sol‐gel, chemical vapor deposition and atomic layer deposition) and electrochemical methods (anodization and microarc oxidation) for SLM Ti and its alloy implants, especially for porous structures. Particularly, the characteristics of these methods are summarized, and their commonly used pre‐ and post‐treatment methods are introduced. In addition, the development trends and challenges in surface modification of SLM Ti and its alloy implants are discussed.
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Ultrasonic peening treatment is a modern technique that enhances the surface properties of the metallic components by imposing static and dynamic loadings. The efficiency of this technique dramatically is dependent on the controlling parameters of ultrasonic peening treatment. In this study, an experimental and numerical investigation on ultrasonic peening treatment was carried out. The numerically predicted residual stress profile was verified using x‐ray diffraction measurement. Moreover, a parametric study was performed to investigate the effect of needle diameter, impact number, device moving velocity and static force on residual stress distribution. Based on the results, increasing in needle diameter, impact number and static force had positive effects on residual stress profile. In contrast, higher device moving velocity caused to emerge undesirable effects. The efficiency of the ultrasonic peening treatment technique is dependent on the controlling parameters. The numerically predicted residual stress profile was verified using x‐ray diffraction measurement. Parametric study was performed to investigate the effect of the controlling parameters such as needle diameter, impact number, device moving velocity and static force on residual stress profile.
Advanced multi-pin ultrasonic impact treatment (UIT) technique is applied to improve the surface properties of AISI O2 tool steel. The main influential parameters, such as amplitude of the horn vibrations and peening intensity (UIT duration), were studied using a factorial design of experiments. The experimental conditions and response surface methodology designs were generated using the Design-Expert software. To optimize the UIT parameters for the manganese steel processing, statistical, diagnostic, and response surface methodology analyses were carried out. The effects of the UIT parameters on the surface crystallite/grain size, hardness, hardening depth, residual macro-stress, roughness, and waviness as response variables were evaluated. The surface topography and profiles of the untreated and UIT-processed specimens were also analyzed and compared. The linear/quadratic regression models were selected to predict the dependent output variables. The optimum UIT parameters were narrowed for the studied steel, setting maximum (hardness, hardening depth, and residual stress) and minimum (grain size, roughness, and waviness) limits. The results showed that the optimized UIT parameters lead to an increase in surface hardness by ~50% and a reduction in surface roughness by ~50%, providing both a specific surface texture and a nanostructure, and compressive residual stress in the subsurface layer.
Plasma arc surface hardening is an alternative selective surface hardening method that is effective, economical and a promising technology in heat treatment industries. In the present work, an investigation was carried out to study the hardness distributions of multiple passes in surface hardening of tool steel by plasma arc. The effects of multiple passes with overlapping and non-overlapping scans were investigated. The results show that the hardness is higher at centre of the plasma arc hardening tracks, and then decreasing in the region adjacent to each plasma arc track. It was found that the formation of hardened zone hardness in multiple passes non-overlapping scan is more uniform on the each scan when compared to the overlapping scan. However, hardness distribution of overlapping scan in width direction shows that it was more uniform compared with non-overlapping scan.
ASM Handbook, Volume 4A is the first in a series of five ASM Handbook volumes covering heat treating. This volume includes 50 articles that address the physical metallurgy of steel heat treatment and thoroughly cover the many steel heat treating processes. Fundamentals of hardness and the use of hardenability as a selection factor are discussed as are the fundamentals of quenching and quenching processes. The volume also discusses annealing, tempering, austempering, and martempering as well as cleaning, subcritical annealing, austenitizing, and quench partitioning. It also presents practical information on surface hardening by applied energy, carburizing, carbonitriding, nitriding, and diffusion coatings. For information on the print version of Volume 4A, ISBN 978-1-62708-011-8, follow this link.
The measurement of residual stresses is very important in exacting dynamically loaded machine parts which have been subjected to different kinds of heat treatment. In designing parts designers very frequently demand the presence of compressive residual stresses after heat treatment and finish grinding of the surface, since this increases the fatigue strength of the material and reduces the danger of fracture. In this investigation the size and variation of residual stresses after lasersurface remelting were measured as a function of the modified layer depth on flat specimens from nodular cast iron. Optimal laser remelting conditions were chosen, while only the way of guiding the laser beam over the surface of flat specimens was varied. To measure the residual stresses, the relaxation method was used, including gradual electro-chemical removal of the modified layer in which the deformation of the specimes was measured by resistance strain gauges.
