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Jens Bergstrom - One of the best experts on this subject based on the ideXlab platform.
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Thermal Fatigue cracking of surface engineered hot work tool steels
Surface & Coatings Technology, 2005Co-Authors: Anders Persson, Sture Hogmark, Jens BergstromAbstract:Abstract Thermal Fatigue cracking is an important life-limiting failure mechanism in die casting tools. It is observed as a network of fine cracks on the surfaces exposed to Thermal cycling. The crack network degrades the surface quality of the tool and, consequently, the surface of the casting. Surface engineered materials are today successfully applied to improve the erosion and corrosion resistance. However, their resistance against Thermal Fatigue is not fully explored. In this work, a selection of hot work tool steel grades was surface modified and experimentally evaluated in a dedicated Thermal Fatigue simulation test. The surface modifications included boriding, nitriding, Toyota diffusion (CrC), and physical vapour deposition (PVD) of coatings (CrC, CrN and TiAlN), both as single-layers and deposited after nitriding (duplex treatment). Untreated specimens of each tool steel grade were used as references. The test is based on cyclic induction heating and internal cooling of hollow cylindrical test rods. The surface strain is continuously recorded through a non-contact laser speckle technique. Generally, all surface treatments decreased the resistance against surface cracking as compared to the reference materials. The reason is that the engineering processes influence negatively on the mechanical properties of the tool materials. Of the processes evaluated, duplex treatment was the least destructive. It gave a lower crack density than the reference steel, but the diffusion layer is more susceptible to crack propagation. In addition, the single-layered CrN coating showed almost comparable Thermal Fatigue cracking resistance as the reference material. Finally, the resistance against Thermal crack propagation of surface engineered tool steels is primarily determined by the mechanical properties of the substrate material.
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Thermal Fatigue testing of chromium martensitic hot-work tool steel after different austenitizing treatments
Journal of Materials Processing Technology, 2004Co-Authors: Johnny Sjostrom, Jens BergstromAbstract:Abstract Tools used in die casting, hot rolling, extrusion and hot forging are exposed to high cyclic temperatures and mechanical loads. Particularly designed hot-work tool steels are frequently used to meet the application requirements, regarding a high Thermal Fatigue resistance as one important tool property. To increase the tool performance, i.e. tool life length, the tool steel microstructural condition may be optimised. In the present study, the Thermal Fatigue properties of a new martensitic chromium hot-work tool steel alloy (Uddeholm designation DIEVAR) have been evaluated with regard to the austenitizing treatment. Using four different austenitizing temperatures, the material was quenched and tempered to the same hardness of 470 HV. Thermal Fatigue was performed using a high frequency induction heating system, designed to simulate hot-work processing conditions, while recording the specimen surface strain with a laser speckle technique. It was found that the Thermal Fatigue crack growth in the tool steel was strongly dependent on the different austenitizing temperatures, as well as the maximum test temperature. Thermal Fatigue resistance was assumed to rely on temper resistance at high maximum cycle temperature and on toughness and ductility at lower. The resistance to Thermal Fatigue could be increased by optimising the heat treatment. The surface mechanical strain during Thermal cycling was estimated from the laser speckle measurements.
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simulation and evaluation of Thermal Fatigue cracking of hot work tool steels
International Journal of Fatigue, 2004Co-Authors: Anders Persson, Sture Hogmark, Jens BergstromAbstract:Abstract Die casting is a very cost efficient method to manufacture near net-shaped and complex cast products. One limitation for further cost reduction is Fatigue cracking of the tool due to Thermal cycling, which is observed as a crack network on the tool surface. Hot work tool steels are commonly used as die material. In this study, an experimental test machine for simulation of Thermal Fatigue is described. The test is based on cyclic induction heating and internal cooling of hollow cylindrical test rods. The surface strain is continuously recorded during the Thermal cycling through a non-contact laser speckle technique. The applicability of the test is demonstrated on two hot work tool steel grades, hardened and tempered to different conditions, and heat cycled between Tmin 170 °C and Tmax 600–850 °C. It is shown that the test method can simulate surface cracking of tools exposed to Thermal Fatigue. The surface strain recordings proved to give sufficient information to successfully deduce the strains and stresses behind the mechanism of Thermal Fatigue surface cracking, without knowledge of the temperature distribution below the surface. It was also found that low-cycle Fatigue occurs for the tests with Tmax 600 and 700 °C, although the estimated tensile stress after cooling does not exceed the initial yield strength of the steel. Most probably, the reason is the gradual softening of the tool steels during the Thermal cycling. Additionally, the presence of stress concentrators play a critical role during these conditions.
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simulation and evaluation of Thermal Fatigue cracking of hot work tool steels
International Journal of Fatigue, 2004Co-Authors: Anders Persson, Sture Hogmark, Jens BergstromAbstract:Die casting is a very cost-efficient method of forming thin-walled and complex near net-shaped products with close geometric tolerances and good surface finish. A permanent die tool is used to make large quantities of identical products. The performance and tool life are limited by several mechanisms, e.g. Thermal Fatigue cracking, erosion, and corrosion. To develop new and more resistant tool materials for die casting detailed knowledge of the actual casting conditions and the tool failure mechanisms are essential. This thesis contributes to an increased knowledge of tool failure in die casting by investigating and simulating actual casting conditions and tool failure mechanisms.A method to record the temperature fluctuations in a cavity insert during actual brass die casting was developed, and details of the temperature conditions were obtained. Also, a test method based on cyclic induction heating and internal cooling of hollow cylindrical test rods was developed, where the surface strain during Thermal cycling could be measured. This method reproduced the characteristic type of surface cracking observed on die casting tools, and proved to give information of the strains and stresses behind the Fatigue failure.In actual die casting, the dominant tool failure mechanism is Thermal Fatigue cracking. The formation of the cracks is associated to accumulation of the local plastic strain that occurs during each casting cycle. Initial crack growth is facilitated by oxidation of the crack surfaces, and proceeded growth is facilitated by this oxidation in combination with crack filling of cast material, and by softening of the tool material. In addition, local enrichment of Pb at the crack front from the cast alloy melt was also observed to promote the crack growth in die casting of brass.In an investigation of Thermal Fatigue of two hot work tool steels, quenched and tempered to different conditions, it was found that low-cycle Fatigue occurs, although the estimated tensile stress never exceed the initial yield strength of the steel. The reason is a gradual softening of the steel during the Thermal cycling, and the presence of stress raising defects. The resistance against Thermal cracking improves with initial tool steel hardness, because any initial ranking in hardness among the steels is unaffected by the Thermal cycling.Another investigation on a selection of surface engineered tool steels, including common diffusion treatments, PVD coatings and combinations of these, showed that surface engineering generally reduce the resistance against Thermal cracking as compared to untreated references, since the engineering processes influence negatively on the mechanical properties of the hot work tool steels.Finally, corrosion tests of CrN PVD-coated tool steels by exposing them to molten aluminium revealed the mechanisms of initiation and progress of liquid metal corrosion of this material combination, and that the corrosion resistance improves with the CrN coating thickness.
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Thermal Fatigue testing of chromium martensitic hot work tool steel after different austenitizing treatments
Proceedings of the International Conference Advanced Materials and Processing Technologies Dublin July 2003, 2003Co-Authors: Johnny Sjostrom, Jens BergstromAbstract:Thermal Fatigue testing of chromium martensitic hot-work tool steel after different austenitizing treatments
Zhihui Zhang - One of the best experts on this subject based on the ideXlab platform.
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The Thermal Fatigue resistance of H13 steel repaired by a biomimetic laser remelting process
Materials & Design, 2014Co-Authors: Dalong Cong, Chao Meng, Zhihui Zhang, Hong Zhou, Haifeng Zhang, Chuanwei WangAbstract:Abstract In this study, the biomimetic laser remelting process was adopted to repair Thermal Fatigue cracks on an annealed hot work die AISI H13 steel. Several treated morphologies: spot, striation and lattice were processed by a pulsed Nd:YAG laser. The ultrafine microstructure within the unit was comprised of martensite, austenite and carbides. The average microhardness of the unit is much higher than that of the original surface, even after Thermal cycles. Thermal Fatigue results show that both crack density and crack length are reduced due to the blocking effect of strengthening units. And the partial laser surface remelting with lattice morphology is the most effective for repairing cracks and improving the Thermal Fatigue resistance of all.
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Thermal Fatigue resistance of h13 steel treated by selective laser surface melting and crni alloying
Applied Surface Science, 2013Co-Authors: Xin Tong, Zhihui ZhangAbstract:Abstract In this study, the selective laser surface melting and laser surface alloying technologies were adopted to improve the Thermal Fatigue resistance of medium carbon hot-work die steel (H13) by a CO 2 laser. Two kinds of mixed chromium (Cr) and nickel (Ni) powders were used as the laser alloying materials, and the effects of the mixing ratio on the Thermal Fatigue resistance were investigated thoroughly. Some important results such as cross-sectional morphology, phases, hardness and Thermal Fatigue behavior were analyzed and evaluated. It indicates that the laser surface alloying technique using mixed powder with ratio of 75%Cr–25%Ni can considerably enhance the Thermal Fatigue resistance of the H13 steel. The laser alloyed zone has excellent properties such as preventing crack initiation and oxidation corrosion compared with original H13. Thermal cracking and oxidation corrosion that occurred at substrate surface can be surrounded and intercepted by a gridded laser strengthened structure. Therefore, the naturally developed cracks could be effectively prevented. Theses results and analysis show that laser surface technique can be positively used to improve surface mechanical properties of H13 dies.
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effect of biomimetic non smooth unit morphology on Thermal Fatigue behavior of h13 hot work tool steel
Optics and Laser Technology, 2012Co-Authors: Chao Meng, Dalong Cong, Chuanwei Wang, Hong Zhou, Peng Zhang, Zhihui ZhangAbstract:Abstract The Thermal Fatigue behavior of hot-work tool steel processed by a biomimetic coupled laser remelting process gets a remarkable improvement compared to untreated sample. The ‘dowel pin effect’, the ‘dam effect’ and the ‘fence effect’ of non-smooth units are the main reason of the conspicuous improvement of the Thermal Fatigue behavior. In order to get a further enhancement of the ‘dowel pin effect’, the ‘dam effect’ and the ‘fence effect’, this study investigated the effect of different unit morphologies (including ‘prolate’, ‘U’ and ‘V’ morphology) and the same unit morphology in different sizes on the Thermal Fatigue behavior of H13 hot-work tool steel. The results showed that the ‘U’ morphology unit had the optimum Thermal Fatigue behavior, then the ‘V’ morphology which was better than the ‘prolate’ morphology unit; when the unit morphology was identical, the Thermal Fatigue behavior of the sample with large unit sizes was better than that of the small sizes.
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effects of graphite shape on Thermal Fatigue resistance of cast iron with biomimetic non smooth surface
International Journal of Fatigue, 2009Co-Authors: Xin Tong, Zhihui Zhang, Hong Zhou, Luquan Ren, Wei Zhang, Rendong CuiAbstract:In order to improve Thermal Fatigue resistance of cast iron and further study the effects of graphite shape on it, samples with different graphite shapes were processed by laser to create a biomimetic non-smooth surface. The results indicated that laser processed zone caused the longer crack initiation life and the slower crack propagation rate, which endowed biomimetic non-smooth surface with a beneficial effect on improving Thermal Fatigue behavior of iron with flake, vermiform or nodular graphite. Thermal Fatigue resistance of samples with the same kind of surface (smooth or non-smooth) all were sorted as nodular graphite iron > vermicular graphite iron > flake graphite iron.
Hong Zhou - One of the best experts on this subject based on the ideXlab platform.
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effects of angle formation between melted zone and friction direction on Thermal Fatigue and wear resistance of truck drum brake
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2021Co-Authors: Ti Zhou, Hong Zhou, Peng Zhang, Yuying YanAbstract:The failure of grey cast iron drum brake is mainly caused by Thermal Fatigue crack running through the top along the axial direction, which has the characteristics of regional failure. By using the...
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effect of unit size on Thermal Fatigue behavior of hot work steel repaired by a biomimetic laser remelting process
Optics and Laser Technology, 2018Co-Authors: Dalong Cong, Peng Zhang, Dajun Chen, Hanbin Chen, Jiuzhou Yang, Hong ZhouAbstract:Abstract AISI H13 hot work steel with Fatigue cracks was repaired by a biomimetic laser remelting (BLR) process in the form of lattice units with different sizes. Detailed microstructural studies and microhardness tests were carried out on the units. Studies revealed a mixed microstructure containing martensite, retained austenite and carbide particles with ultrafine grain size in units. BLR samples with defect-free units exhibited superior Thermal Fatigue resistance due to microstructure strengthening, and mechanisms of crack tip blunting and blocking. In addition, effects of unit size on Thermal Fatigue resistance of BLR samples were discussed.
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The Thermal Fatigue resistance of H13 steel repaired by a biomimetic laser remelting process
Materials & Design, 2014Co-Authors: Dalong Cong, Chao Meng, Zhihui Zhang, Hong Zhou, Haifeng Zhang, Chuanwei WangAbstract:Abstract In this study, the biomimetic laser remelting process was adopted to repair Thermal Fatigue cracks on an annealed hot work die AISI H13 steel. Several treated morphologies: spot, striation and lattice were processed by a pulsed Nd:YAG laser. The ultrafine microstructure within the unit was comprised of martensite, austenite and carbides. The average microhardness of the unit is much higher than that of the original surface, even after Thermal cycles. Thermal Fatigue results show that both crack density and crack length are reduced due to the blocking effect of strengthening units. And the partial laser surface remelting with lattice morphology is the most effective for repairing cracks and improving the Thermal Fatigue resistance of all.
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comparison of Thermal Fatigue behaviour and microstructure of different hot work tool steels processed by biomimetic couple laser remelting process
Materials Science and Technology, 2013Co-Authors: Chao Meng, Dalong Cong, Chuanwei Wang, Hong Zhou, Xin Tong, Luquan RenAbstract:AbstractFor comparing the enhancement degree of the Thermal Fatigue behaviour of different hot work tool steels processed by laser remelting, three kinds of hot work tool steels (HHD, H13 and HD steels) were selected to investigate the effect of biomimetic coupled laser remelting process on the Thermal Fatigue behaviour. The results showed that biomimetic non-smooth samples had better Thermal Fatigue behaviour compared to untreated samples, the biomimetic non-smooth sample of HHD had the optimum Thermal Fatigue behaviour. Moreover, before and after Thermal Fatigue testing, the microhardness and microstructure of biomimetic non-smooth units and parent materials have been investigated. The results showed that biomimetic non-smooth sample of HHD had the highest resistance of Thermal cycles softening among the biomimetic non-smooth samples. The microstructures observation indicated that the microstructures of parent materials were a substantial amount of the carbides coarsening while the microstructures of bi...
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effect of biomimetic non smooth unit morphology on Thermal Fatigue behavior of h13 hot work tool steel
Optics and Laser Technology, 2012Co-Authors: Chao Meng, Dalong Cong, Chuanwei Wang, Hong Zhou, Peng Zhang, Zhihui ZhangAbstract:Abstract The Thermal Fatigue behavior of hot-work tool steel processed by a biomimetic coupled laser remelting process gets a remarkable improvement compared to untreated sample. The ‘dowel pin effect’, the ‘dam effect’ and the ‘fence effect’ of non-smooth units are the main reason of the conspicuous improvement of the Thermal Fatigue behavior. In order to get a further enhancement of the ‘dowel pin effect’, the ‘dam effect’ and the ‘fence effect’, this study investigated the effect of different unit morphologies (including ‘prolate’, ‘U’ and ‘V’ morphology) and the same unit morphology in different sizes on the Thermal Fatigue behavior of H13 hot-work tool steel. The results showed that the ‘U’ morphology unit had the optimum Thermal Fatigue behavior, then the ‘V’ morphology which was better than the ‘prolate’ morphology unit; when the unit morphology was identical, the Thermal Fatigue behavior of the sample with large unit sizes was better than that of the small sizes.
Anders Persson - One of the best experts on this subject based on the ideXlab platform.
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Thermal Fatigue cracking of surface engineered hot work tool steels
Surface & Coatings Technology, 2005Co-Authors: Anders Persson, Sture Hogmark, Jens BergstromAbstract:Abstract Thermal Fatigue cracking is an important life-limiting failure mechanism in die casting tools. It is observed as a network of fine cracks on the surfaces exposed to Thermal cycling. The crack network degrades the surface quality of the tool and, consequently, the surface of the casting. Surface engineered materials are today successfully applied to improve the erosion and corrosion resistance. However, their resistance against Thermal Fatigue is not fully explored. In this work, a selection of hot work tool steel grades was surface modified and experimentally evaluated in a dedicated Thermal Fatigue simulation test. The surface modifications included boriding, nitriding, Toyota diffusion (CrC), and physical vapour deposition (PVD) of coatings (CrC, CrN and TiAlN), both as single-layers and deposited after nitriding (duplex treatment). Untreated specimens of each tool steel grade were used as references. The test is based on cyclic induction heating and internal cooling of hollow cylindrical test rods. The surface strain is continuously recorded through a non-contact laser speckle technique. Generally, all surface treatments decreased the resistance against surface cracking as compared to the reference materials. The reason is that the engineering processes influence negatively on the mechanical properties of the tool materials. Of the processes evaluated, duplex treatment was the least destructive. It gave a lower crack density than the reference steel, but the diffusion layer is more susceptible to crack propagation. In addition, the single-layered CrN coating showed almost comparable Thermal Fatigue cracking resistance as the reference material. Finally, the resistance against Thermal crack propagation of surface engineered tool steels is primarily determined by the mechanical properties of the substrate material.
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simulation and evaluation of Thermal Fatigue cracking of hot work tool steels
International Journal of Fatigue, 2004Co-Authors: Anders Persson, Sture Hogmark, Jens BergstromAbstract:Abstract Die casting is a very cost efficient method to manufacture near net-shaped and complex cast products. One limitation for further cost reduction is Fatigue cracking of the tool due to Thermal cycling, which is observed as a crack network on the tool surface. Hot work tool steels are commonly used as die material. In this study, an experimental test machine for simulation of Thermal Fatigue is described. The test is based on cyclic induction heating and internal cooling of hollow cylindrical test rods. The surface strain is continuously recorded during the Thermal cycling through a non-contact laser speckle technique. The applicability of the test is demonstrated on two hot work tool steel grades, hardened and tempered to different conditions, and heat cycled between Tmin 170 °C and Tmax 600–850 °C. It is shown that the test method can simulate surface cracking of tools exposed to Thermal Fatigue. The surface strain recordings proved to give sufficient information to successfully deduce the strains and stresses behind the mechanism of Thermal Fatigue surface cracking, without knowledge of the temperature distribution below the surface. It was also found that low-cycle Fatigue occurs for the tests with Tmax 600 and 700 °C, although the estimated tensile stress after cooling does not exceed the initial yield strength of the steel. Most probably, the reason is the gradual softening of the tool steels during the Thermal cycling. Additionally, the presence of stress concentrators play a critical role during these conditions.
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simulation and evaluation of Thermal Fatigue cracking of hot work tool steels
International Journal of Fatigue, 2004Co-Authors: Anders Persson, Sture Hogmark, Jens BergstromAbstract:Die casting is a very cost-efficient method of forming thin-walled and complex near net-shaped products with close geometric tolerances and good surface finish. A permanent die tool is used to make large quantities of identical products. The performance and tool life are limited by several mechanisms, e.g. Thermal Fatigue cracking, erosion, and corrosion. To develop new and more resistant tool materials for die casting detailed knowledge of the actual casting conditions and the tool failure mechanisms are essential. This thesis contributes to an increased knowledge of tool failure in die casting by investigating and simulating actual casting conditions and tool failure mechanisms.A method to record the temperature fluctuations in a cavity insert during actual brass die casting was developed, and details of the temperature conditions were obtained. Also, a test method based on cyclic induction heating and internal cooling of hollow cylindrical test rods was developed, where the surface strain during Thermal cycling could be measured. This method reproduced the characteristic type of surface cracking observed on die casting tools, and proved to give information of the strains and stresses behind the Fatigue failure.In actual die casting, the dominant tool failure mechanism is Thermal Fatigue cracking. The formation of the cracks is associated to accumulation of the local plastic strain that occurs during each casting cycle. Initial crack growth is facilitated by oxidation of the crack surfaces, and proceeded growth is facilitated by this oxidation in combination with crack filling of cast material, and by softening of the tool material. In addition, local enrichment of Pb at the crack front from the cast alloy melt was also observed to promote the crack growth in die casting of brass.In an investigation of Thermal Fatigue of two hot work tool steels, quenched and tempered to different conditions, it was found that low-cycle Fatigue occurs, although the estimated tensile stress never exceed the initial yield strength of the steel. The reason is a gradual softening of the steel during the Thermal cycling, and the presence of stress raising defects. The resistance against Thermal cracking improves with initial tool steel hardness, because any initial ranking in hardness among the steels is unaffected by the Thermal cycling.Another investigation on a selection of surface engineered tool steels, including common diffusion treatments, PVD coatings and combinations of these, showed that surface engineering generally reduce the resistance against Thermal cracking as compared to untreated references, since the engineering processes influence negatively on the mechanical properties of the hot work tool steels.Finally, corrosion tests of CrN PVD-coated tool steels by exposing them to molten aluminium revealed the mechanisms of initiation and progress of liquid metal corrosion of this material combination, and that the corrosion resistance improves with the CrN coating thickness.
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strain based approach to crack growth and Thermal Fatigue life of hot work tool steels
Scandinavian Journal of Metallurgy, 2004Co-Authors: Anders PerssonAbstract:Thermal Fatigue cracking is one of the most important life-limiting tool failure mechanisms in die casting of aluminium and brass. It results from the rapid alternating heating and cooling of the die surface during the casting process, and it is observed as a network of fine cracks on the tool surfaces exposed to Thermal cycling. The crack pattern deteriorates the surface finish of the tool and, therefore, that of the cast products. Hot work tool steels are frequently used as die materials to minimise this tool damage. In this study, Thermal Fatigue cracking of two hot work tool steel grades, hardened and tempered to various conditions, were evaluated using an experimental Thermal Fatigue test method based on cyclic induction heating and internal cooling of hollow cylindrical test rods. The surface strain is continuously recorded during the Thermal cycling through a noncontact laser speckle technique. The Thermal Fatigue damage was characterised with respect to crack length and density of cracks. Based on the experimental findings estimations of crack growth and Thermal Fatigue life, and their temperature sensitivity were made. In addition, the crack growth and Thermal Fatigue life were represented using strain-based models. It was found that the resistance against Thermal cracking improves with initial tool steel hardness, in spite of the fact that Thermal Fatigue causes considerable softening, and that the initial ranking in hardness among the different steels is unaffected by Thermal cycling. The cyclic Thermal crack growth rate increases roughly with one order of magnitude when increasing the maximum cycle temperature from 700 to 850°C. In addition, an increase in the maximum cycle temperature from 600 to 700°C and from 700 to 850°C reduces the Thermal Fatigue life with roughly one order of magnitude, respectively.
Chuanwei Wang - One of the best experts on this subject based on the ideXlab platform.
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The Thermal Fatigue resistance of H13 steel repaired by a biomimetic laser remelting process
Materials & Design, 2014Co-Authors: Dalong Cong, Chao Meng, Zhihui Zhang, Hong Zhou, Haifeng Zhang, Chuanwei WangAbstract:Abstract In this study, the biomimetic laser remelting process was adopted to repair Thermal Fatigue cracks on an annealed hot work die AISI H13 steel. Several treated morphologies: spot, striation and lattice were processed by a pulsed Nd:YAG laser. The ultrafine microstructure within the unit was comprised of martensite, austenite and carbides. The average microhardness of the unit is much higher than that of the original surface, even after Thermal cycles. Thermal Fatigue results show that both crack density and crack length are reduced due to the blocking effect of strengthening units. And the partial laser surface remelting with lattice morphology is the most effective for repairing cracks and improving the Thermal Fatigue resistance of all.
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comparison of Thermal Fatigue behaviour and microstructure of different hot work tool steels processed by biomimetic couple laser remelting process
Materials Science and Technology, 2013Co-Authors: Chao Meng, Dalong Cong, Chuanwei Wang, Hong Zhou, Xin Tong, Luquan RenAbstract:AbstractFor comparing the enhancement degree of the Thermal Fatigue behaviour of different hot work tool steels processed by laser remelting, three kinds of hot work tool steels (HHD, H13 and HD steels) were selected to investigate the effect of biomimetic coupled laser remelting process on the Thermal Fatigue behaviour. The results showed that biomimetic non-smooth samples had better Thermal Fatigue behaviour compared to untreated samples, the biomimetic non-smooth sample of HHD had the optimum Thermal Fatigue behaviour. Moreover, before and after Thermal Fatigue testing, the microhardness and microstructure of biomimetic non-smooth units and parent materials have been investigated. The results showed that biomimetic non-smooth sample of HHD had the highest resistance of Thermal cycles softening among the biomimetic non-smooth samples. The microstructures observation indicated that the microstructures of parent materials were a substantial amount of the carbides coarsening while the microstructures of bi...
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effect of biomimetic non smooth unit morphology on Thermal Fatigue behavior of h13 hot work tool steel
Optics and Laser Technology, 2012Co-Authors: Chao Meng, Dalong Cong, Chuanwei Wang, Hong Zhou, Peng Zhang, Zhihui ZhangAbstract:Abstract The Thermal Fatigue behavior of hot-work tool steel processed by a biomimetic coupled laser remelting process gets a remarkable improvement compared to untreated sample. The ‘dowel pin effect’, the ‘dam effect’ and the ‘fence effect’ of non-smooth units are the main reason of the conspicuous improvement of the Thermal Fatigue behavior. In order to get a further enhancement of the ‘dowel pin effect’, the ‘dam effect’ and the ‘fence effect’, this study investigated the effect of different unit morphologies (including ‘prolate’, ‘U’ and ‘V’ morphology) and the same unit morphology in different sizes on the Thermal Fatigue behavior of H13 hot-work tool steel. The results showed that the ‘U’ morphology unit had the optimum Thermal Fatigue behavior, then the ‘V’ morphology which was better than the ‘prolate’ morphology unit; when the unit morphology was identical, the Thermal Fatigue behavior of the sample with large unit sizes was better than that of the small sizes.
