| 摘要: |
| 为了研究增强 32Cr3Mo1V 铸轧辊套材料的热疲劳性能的方法,使用连续 Nd:YAG 激光制备表面离散 Cr 合金化试样。 使用激光扫描加热模拟实际辊套的表面温度和分布,测试试样的热疲劳性能。 通过对试样的准原位观察,发现疲劳裂纹在氧化膜点蚀处萌生并扩展。 通过 SEM 观察和 EDAX 分析,发现在热循环 300 周次时,基体中的 Cr 元素已经耗尽,形成疲劳裂纹,而合金化区和热影响区的组织保持完整。 合金化区中 Cr 含量达到 10. 41%,含氧量仅为基体的 2. 8%;热影响区的 Cr 元素含量为 3. 41%,含氧量为基体的 7. 2%。 结合金属高温氧化理论和材料疲劳理论分析,认为高 Cr 含量在试样表面形成薄且致密的氧化膜,抑制氧化膜的点蚀现象,避免裂纹的萌生;而热影响区中显微组织的高 Cr 含量和残余压应力结合阻滞疲劳裂纹的扩展,使裂纹扩展速率降低近一个量级。 |
| 关键词: 激光 热疲劳 铸轧辊套 表面离散 Cr 合金化 |
| DOI：10.11933/j.issn.1007-9289.20190415004 |
| 分类号:TG174.46 |
| 文章编号:1007-9289(2020)01-0110-07 |
| 文献标识码:A |
| 基金项目:国家自然科学基金(11372322, 60877064) |
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| Thermal Fatigue Performance of Laser Surface Discrete Chrome Alloyed 32Cr3Mo1V Steel |
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Li Wen, Wang Zhitong
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Key Lab of Mechanics in Advanced Manufacturing, Institute of Mechanics, Chinese Academy Science, Beijing 100190 , China
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| Abstract: |
| In order to study the method improving the thermal fatigue performance of 32Cr3Mo1V steel used in the casting roll sleeve, the surface discrete chrome alloyed specimens were prepared by continuous Nd:YAG laser. The surface temperature and distribution of the actual roller sleeve were simulated by laser scanning heating, and the thermal fatigue properties of the samples were tested. In the in-situ observation of specimen, fatigue cracks were found to initiate and propagate at the oxide film pitting. By means of SEM observation and EDAX analysis to the specimens, it was found in the base material by heat cycling 300 times that the chrome elements had been exhausted and the fatigue cracks had been formed, while the microstructures of alloyed zone and heat affected zone (HAZ) remains intact. By heat cycling 300 times the content of chrome is 10. 41% and the content of oxygen is only 2. 8% of that of the base material in the alloyed zone, and the content of chrome is 3. 41% and the content of oxygen is 7. 2% of that of the base material in HAZ. Based on the theories of high-temperature oxidation and material fatigue, it is considered that high chrome content of material forms a kind of thin and compact oxide film on the surface of specimen, which suppresses the pitting of the oxide film and avoids the initiation of crack, while the combination of high chrome content and residual compressive stress in the microstructures of HAZ blocks the propagation of fatigue crack and reduces the crack growth rate by nearly one order of magnitude. |
| Key words: laser thermal fatigue casting roll sleeve surface discrete chrome alloying |
