Influence of TiN Inclusions and Segregation Bands on the Mechanical Properties and Delayed Crack in Thick NM550 Wear-Resistant Steel
The formation mechanism of the delayed crack after flame cutting and mechanical properties in thick NM550 wear-resistant steel are studied by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and an electron backscattered diffractometer. The delayed...
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MDPI AG
2023-08-01
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| author | Haoran Sun Hegang Du Keke Tong Lihua Liu Qiangjun Yan Xiurong Zuo |
| author_facet | Haoran Sun Hegang Du Keke Tong Lihua Liu Qiangjun Yan Xiurong Zuo |
| author_sort | Haoran Sun |
| collection | DOAJ |
| description | The formation mechanism of the delayed crack after flame cutting and mechanical properties in thick NM550 wear-resistant steel are studied by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and an electron backscattered diffractometer. The delayed crack is formed at the segregation zone (SZ) located in the center of the 65 mm thick steel plate. The strength of the non-segregation zone (NSZ) with a martensite microstructure is slightly higher than that of SZ with a mixture microstructure of martensite plus bainite, and the plasticity of NSZ is significantly better than that of SZ. There exists a more severe segregation in the SZ, and only a slight segregation in the NSZ. The average grain sizes of the segregation bands in the NSZ and SZ are 15.72 µm and 6.76 µm, respectively. The number density of TiN larger than 5 µm in the NSZ and SZ is 0.031 and 1.156 number/mm<sup>2</sup>, respectively. Therefore, a high hardness segregation band with fine grains and a high dislocation density, along with the large number of coarse TiN inclusions within it, results in delayed cracking. For TiN inclusions close to the crack, microvoids or microcracks around the TiN are formed, and the delayed crack will propagate along the edge of the TiN or through the TiN inclusions. |
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| id | doaj.art-eb5050e93d1e4e458180fbe1c6b26fa2 |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-10T23:19:00Z |
| publishDate | 2023-08-01 |
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| spelling | doaj.art-eb5050e93d1e4e458180fbe1c6b26fa22023-11-19T08:26:53ZengMDPI AGMaterials1996-19442023-08-011617585610.3390/ma16175856Influence of TiN Inclusions and Segregation Bands on the Mechanical Properties and Delayed Crack in Thick NM550 Wear-Resistant SteelHaoran Sun0Hegang Du1Keke Tong2Lihua Liu3Qiangjun Yan4Xiurong Zuo5Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, ChinaKey Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, ChinaKey Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, ChinaNanjing Iron & Steel Co., Ltd., Nanjing 210035, ChinaNanjing Iron & Steel Co., Ltd., Nanjing 210035, ChinaKey Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450001, ChinaThe formation mechanism of the delayed crack after flame cutting and mechanical properties in thick NM550 wear-resistant steel are studied by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and an electron backscattered diffractometer. The delayed crack is formed at the segregation zone (SZ) located in the center of the 65 mm thick steel plate. The strength of the non-segregation zone (NSZ) with a martensite microstructure is slightly higher than that of SZ with a mixture microstructure of martensite plus bainite, and the plasticity of NSZ is significantly better than that of SZ. There exists a more severe segregation in the SZ, and only a slight segregation in the NSZ. The average grain sizes of the segregation bands in the NSZ and SZ are 15.72 µm and 6.76 µm, respectively. The number density of TiN larger than 5 µm in the NSZ and SZ is 0.031 and 1.156 number/mm<sup>2</sup>, respectively. Therefore, a high hardness segregation band with fine grains and a high dislocation density, along with the large number of coarse TiN inclusions within it, results in delayed cracking. For TiN inclusions close to the crack, microvoids or microcracks around the TiN are formed, and the delayed crack will propagate along the edge of the TiN or through the TiN inclusions.https://www.mdpi.com/1996-1944/16/17/5856NM550 wear-resistant steelsegregation bandTiN inclusionmechanical propertydelayed crack |
| spellingShingle | Haoran Sun Hegang Du Keke Tong Lihua Liu Qiangjun Yan Xiurong Zuo Influence of TiN Inclusions and Segregation Bands on the Mechanical Properties and Delayed Crack in Thick NM550 Wear-Resistant Steel Materials NM550 wear-resistant steel segregation band TiN inclusion mechanical property delayed crack |
| title | Influence of TiN Inclusions and Segregation Bands on the Mechanical Properties and Delayed Crack in Thick NM550 Wear-Resistant Steel |
| title_full | Influence of TiN Inclusions and Segregation Bands on the Mechanical Properties and Delayed Crack in Thick NM550 Wear-Resistant Steel |
| title_fullStr | Influence of TiN Inclusions and Segregation Bands on the Mechanical Properties and Delayed Crack in Thick NM550 Wear-Resistant Steel |
| title_full_unstemmed | Influence of TiN Inclusions and Segregation Bands on the Mechanical Properties and Delayed Crack in Thick NM550 Wear-Resistant Steel |
| title_short | Influence of TiN Inclusions and Segregation Bands on the Mechanical Properties and Delayed Crack in Thick NM550 Wear-Resistant Steel |
| title_sort | influence of tin inclusions and segregation bands on the mechanical properties and delayed crack in thick nm550 wear resistant steel |
| topic | NM550 wear-resistant steel segregation band TiN inclusion mechanical property delayed crack |
| url | https://www.mdpi.com/1996-1944/16/17/5856 |
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