论文总字数：16729字

摘 要

钛及其钛的合金相较于其它常见金属，它的强度更高，耐蚀性能更优良，低温的时候更加能保持自己的各项物理性质，所以钛及其钛合金非常适合应用于海洋工程材料。故此，本文将Ti-Al-Fe-B合金作为研究对象，探究了它在海洋环境中有关于应力腐蚀的一些问题。本次试验，分别对钛合金试样进行了XRD分析，慢应变拉伸试验，开路电位的测定和金相观察，以此来研究钛合金在模拟海水中的应力腐蚀性能。通过上述研究，得出以下结论：

（1）该合金由α相和β相组成，由于β相稳定元素Fe的含量非常少，故形成的β相相对较少，只占相含量的2.4%，大部分则是由α相构成。

（2）通过慢应变拉伸试验结果，我们可以看出，钛合金试样在应变速率为5×时应力腐蚀敏感性指数更高，就是说在此速率下，试样更容易发生应力腐蚀，从而导致合金材料的失效。当应变速率降低为5×时，合金的应力腐蚀敏感指数降低，I值由0.17降低到0.14，As/Aa值由0.836升高到0.927，由此可得，随着应变速率的降低，应力腐蚀敏感性降低。

（3）开路电位的数据图显示，相对于应变速率为6×10^-6s^-1下的试样，应变速率为5×下试样的开路电位更低，说明其抗腐蚀能力更弱。

关键字：钛合金 应变速率 应力腐蚀 海洋作业

Abstract

Compared with other common metals, titanium and its alloys have higher strength, better corrosion resistance, and can maintain their physical properties at low temperatures, so titanium and their titanium alloys are very suitable for marine engineering material.Therefore, this article takes Ti-Al-Fe-B titanium alloy as the research object and explores some of its problems related to stress corrosion in the marine environment. In this test, the XRD analysis, slow strain tensile test, open circuit potential measurement and metallographic observation were carried out on the titanium alloy sample to study the stress corrosion performance of the titanium alloy in simulated seawater. Through the above research, the following conclusions are drawn:

(1) The alloy consists of α-phase and β-phase. Since the content of β-phase stabilizing element Fe is very small, the β-phase formed is relatively small, accounting for only 2.4% of the phase content, and most of it is composed of α-phase.

(2) Through the results of the slow strain tensile test, we can see that the stress corrosion sensitivity index of the titanium alloy sample is higher when the strain rate is 5×, that is , The sample is more prone to stress corrosion, which leads to the failure of the alloy material. When the strain rate is reduced to 5×, the stress corrosion sensitivity index of the alloy decreases, the I value decreases from 0.17 to 0.14, and the As / Aa value increases from 0.836 to 0.927. It can be seen that as the strain rate decreases, the stress corrosion sensitivity decreases .

(3) The data graph of the open circuit potential shows that the sample has a lower open circuit potential at a strain rate of5× relative to the sample at a strain rate of 5× It shows that its corrosion resistance is weaker.

Keywords: Titanium alloy, Marine environment, Stress corrosion，Marine operations

目 录

摘要 I

Abstract II

第一章 绪论 1

1.1 钛合金 1

1.1.1 钛合金的概述 1

1.1.2 钛合金的性能 1

1.1.3 钛合金分类 2

1.2 钛合金腐蚀的分类 3

1.2.1 应力腐蚀 3

1.2.2 点蚀 4

1.2.3 缝隙腐蚀 4

1.2.4 均匀腐蚀 5

1.3 应力腐蚀研究现状 5

1.4 研究目的和意义 8

第二章 实验方案方法和材料设备 9

2.1 实验材料及设备 9

2.2 实验方案 11

2.3 实验内容 12

2.3.1 XRD分析 12

2.3.2 拉伸 12

2.3.3 开路电位的测定 13

第三章 实验结果和讨论 14

3.1 金相观察 14

3.2 XRD分析 14

3.3 慢应变速率下的拉伸试验 15

3.4 慢拉伸试验过程中的开路电位变化 16

第四章 结论 18

第五章 展望 19

参考文献 22

致 谢 24

第一章 绪论

1.1 钛合金

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