| GAO Zhi-heng,FU Yang-fan.Salt-bath Nitriding Process for 32Cr2Mo2NiVNb Steel[J],44(10):68-73 |
| Salt-bath Nitriding Process for 32Cr2Mo2NiVNb Steel |
| Received:August 25, 2015 Revised:October 20, 2015 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2015.10.012 |
| KeyWord:32Cr2Mo2NiVNb steel salt-bath nitriding microstructure mechanical property corrosion resistance high-temperature wear resistance |
| Author | Institution |
| GAO Zhi-heng |
Representative Bureau of Naval Equipment Department in Chongqing, Chongqing , China |
| FU Yang-fan |
Southwest Technology and Engineering Research Institute, Chongqing , China |
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| Abstract: |
| Objective To develop a new salt-bath nitriding process for 32Cr2Mo2NiVNb steel surface treatment. Methods The 32Cr2Mo2NiVNb steel was treated with the new salt-bath nitriding process. The influences of the new salt-bath nitriding process on the microstructure and mechanical properties of 32Cr2Mo2NiVNb steel were concluded based on the analysis of several tests such as salt spray test and hardness test. The applicability of the salt-bath nitriding process for 32Cr2Mo2NiVNb steel was verified in this paper. Results After the salt-bath nitriding process, the 32Cr2Mo2NiVNb base material was composed of uniform fine needle-like sorbite + small amount of free ferrite, the depth of the nitriding layer was about 0. 23 mm, and the compound layer showed an even thickness of about 17 μm. The level of the brittleness, nervation and wave-like nitrid, porosity of nitrided case all reached grade I. The hardness of 32Cr2Mo2NiVNb steel surface after salt-bath nitriding treatment was 1011HV0. 3, which was 250% of the surface hardness without salt-bath nitriding treatment. The tensile strength and the fracture morphology showed no significant change after salt-bath nitriding treatment. The tensile length after fracture, the reduction of cross-section area and impact absorption energy were slightly decreased. The time of resistance to neutral salt spray was 6. 3 fold as high as that of the sample coated with hard chromium. The surface wear scars after wear at high temperature for 190 s were fine and uniform, and the wear weight loss was reduced by 62. 8% as compared to the sample coated with hard chromium. Conclusion The salt-bath nitriding process did not damage the microstructure and mechanical properties of 32Cr2Mo2NiVNb steel, with only slight decreased in plasticity and toughness indexes, and could significantly improve the corrosion resistance and high-temperature wear resistance of 32Cr2Mo2NiVNb steel as compared to hard chromium plating. The new salt-bath nitriding process was well suitable for surface treatment of 32Cr2Mo2NiVNb steel. |
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