【摘要】：0Cr25Ni35AlTi是我國自主研發(fā)的一種適用于苛刻環(huán)境的Fe-Ni-Cr合金,具有優(yōu)良耐晶間腐蝕和力學性能,可應用在壓水堆裝置蒸汽發(fā)生器傳熱管。0Cr25Ni35AlTi合金力學性能和耐蝕性的匹配與合金成分密切相關,尤其合金中的C含量對合金的性能有極大的影響。因此,通過系統(tǒng)地研究C含量對合金的性能的影響規(guī)律,對于優(yōu)化0Cr25Ni35AlTi合金成分和加工工藝具有重要的實用價值。本文采用光學顯微鏡、掃描電鏡、透射電鏡和物理化學相等方法對不同C含量的0Cr25Ni35AlTi合金的組織、力學性能、析出相以及變形特性進行了測試,,并應用失重法和電化學方法研究了合金耐蝕性能。研究結果表明：0Cr25Ni35AlTi合金隨著碳含量的增加,其平均晶粒尺寸減小,M23C6析出量增加,合金的力學性能提高,但合金的耐晶間腐蝕性能下降,當合金中C含量控制在0.025%左右,具有良好的耐晶間腐蝕性能,且其強度仍能保持在300MPa以上,滿足合金的應用性能指標。冷變形會對0Cr25Ni35AlTi合金的力學性能和耐蝕性能產(chǎn)生明顯的影響,隨著變形量增加,組織中變形帶增多變密,孿晶數(shù)量增加而且發(fā)生彎曲變形,導致合金的強度、硬度增加,塑性降低,加工硬化能力降低,同時合金的耐點蝕性能降低。隨著碳含量增加,合金中析出數(shù)量增加且聚集長大,耐蝕性降低。其中合金在650℃時效處理2h后,由于晶界區(qū)域鉻出現(xiàn)嚴重貧化,耐晶間腐蝕性能最差�；跓釅嚎s實驗建立了0Cr25Ni35AlTi合金的熱變形本構方程,該方程可以描述合金在熱變形過程中變形溫度、應變速率和峰值應力的關系。通過觀察不同熱變形條件下的再結晶行為,發(fā)現(xiàn)增加變形溫度或者減小應變速率,有利于合金熱變形過程中發(fā)生動態(tài)再結晶。碳含量對0Cr25Ni35AlTi合金動態(tài)再結晶過程產(chǎn)生明顯的影響,隨著碳含量增加,合金的動態(tài)再結晶進程越遲緩。同時變形激活能增加,變形難度增大。
[Abstract]:0Cr25Ni35AlTi is a self-developed Fe-Ni-Cr alloy suitable for harsh environment. It has excellent intergranular corrosion resistance and mechanical properties. The matching of mechanical properties and corrosion resistance of 0Cr25Ni35AlTi alloy is closely related to the composition of the alloy, especially the content of C in the alloy has a great influence on the properties of the alloy. Therefore, it is of great practical value to optimize the composition and processing technology of 0Cr25Ni35AlTi alloy by systematically studying the effect of C content on the properties of the alloy. In this paper, the microstructure, mechanical properties, precipitation phase and deformation characteristics of 0Cr25Ni35AlTi alloy with different C content were measured by optical microscope, scanning electron microscope, transmission electron microscope and physicochemical equivalent method. The corrosion resistance of the alloy was studied by weight loss method and electrochemical method. The results show that with the increase of carbon content, the average grain size of 0Cr25Ni35AlTi alloy decreases, the amount of M23C6 precipitates increases, the mechanical properties of the alloy increase, but the intergranular corrosion resistance of the alloy decreases, when the content of C in the alloy is controlled at about 0.025%. It has good intergranular corrosion resistance, and its strength can still be kept above 300MPa, which meets the application performance index of the alloy. Cold deformation has an obvious effect on the mechanical properties and corrosion resistance of 0Cr25Ni35AlTi alloys. With the increase of deformation amount, the deformation bands in the microstructure become more dense, the number of twins increases and the bending deformation occurs, which results in the increase of the strength and hardness of the alloy. The plasticity is reduced, the work hardening ability is decreased, and the pitting corrosion resistance of the alloy is decreased. With the increase of carbon content, the amount of precipitation in the alloy increases, and the corrosion resistance decreases. After aging at 650 鈩，

本文編號：2397463