Evolution of microstructure and properties of cold-drawn 07Cr17Ni7Al ultrafine wire
The elastic limit is a critical parameter in spring design， which has a significant impact on the spring characteristic. The influence of cold drawing on the strength， elastic limit， elastic after-effect， and microstructure of 07Cr17Ni7Al ultrafine wire with a diameter of 0.3 mm for valve springs is...
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| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | zho |
| Published: |
Journal of Materials Engineering
2025-03-01
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| Series: | Cailiao gongcheng |
| Subjects: | |
| Online Access: | https://jme.biam.ac.cn/CN/10.11868/j.issn.1001-4381.2023.000785 |
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| Summary: | The elastic limit is a critical parameter in spring design， which has a significant impact on the spring characteristic. The influence of cold drawing on the strength， elastic limit， elastic after-effect， and microstructure of 07Cr17Ni7Al ultrafine wire with a diameter of 0.3 mm for valve springs is investigated using room temperature tensile tests， single arm bending method， optical microscope（OM）， X-ray diffraction（XRD） and scanning electron microscope（SEM）. Different mathematical models are used to fit and analyze the deformation and martensite content， deformation-elastic limit， and stress-elastic after-effect. The results show that the solid solution 07Cr17Ni7Al wire is composed of austenite and a small amount of ferrite. Cold drawing transforms austenite into martensite， the content of deformation-induced martensite （DIM） increases with increasing deformation. The relationship between DIM content and cold-drawn equivalent strain （η） conforms to the Olson-Cohen model. When η reaches 1.64， the DIM content is about 92%， and the DIM reaches saturation. The tensile strength of wire exhibits a linear relationship with η， and the larger the deformation， the higher the tensile strength. The relationship between the elastic limit and the η follows an “S” shaped curve and conforms to the DoseResp model. The elastic limit increases with increasing deformation. When the η reaches 1.64 or more， the elastic limit tends to be gentle. The elastic after-effect increases with increasing stress， which conforms to the PWL2 model. There exists a “critical stress for elastic after-effect”. When the stress exceeds this critical value， the rate of elastic after-effect increases by 2-11 times with increasing stress. When the η is 1.64-2.41， the 07Cr17Ni7Al wire has good mechanical and elastic properties. |
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| ISSN: | 1001-4381 |