Corrosion Observation and Analysis
Metallic materials, which are used in automobiles and various other products, can corrode drastically in unexpected areas and cause fractures.
腐蚀零件的分析对于确定原因和防止再发生很重要，并且使用显微镜观察腐蚀部分的形式。但是，使用常规显微镜观察有各种问题。
本节解释了腐蚀测试程序以及腐蚀的形式和原因，同时介绍了使用4K数字显微镜解决问题的示例。
腐蚀测试重要性和过程
Corrosion refers to the phenomenon in which metallic and other solid materials are deteriorated, consumed, or damaged due to chemical or electrochemical reactions with the surrounding environment, leading to loss of original functions. There are various forms of corrosion such as intergranular corrosion, pitting, crevice corrosion, contact corrosion, and stress corrosion cracking (trans granular cracking and grain boundary cracking), all of which differ depending on the material and the environment.
To investigate the causes of corrosion and prevent reoccurrences, corrosion tests are conducted in a wide variety of industries. In particular, corrosion tests are important for products, such as automobiles, that are composed of various materials and whose safety is required in various outdoor environments.
通常，根据以下程序进行腐蚀测试。
腐蚀测试程序
- 发生腐蚀的区域的外观观察
- Check the area where corrosion has occurred, the color of the item, and the status of the corroded parts.
- Observation by cutting out or removing the corroded parts
- 切出腐蚀的零件。如果难以将它们切出，请仅取下腐蚀的零件。
- 详细观察腐蚀部分和腐蚀物质的元素分析
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(1) Using a microscope, observe the surface of the corroded parts in detail to check the status of the corroded parts and substances. In some cases, the corroded parts are cleaned to check for pitting and other corrosion on the surface of the substrate.
（2）分析腐蚀物质的成分（元素分析）以确认促进腐蚀的物质。 - 腐蚀部分的横截面观察
- 如有必要，将腐蚀零件处理成横截面样品以检查腐蚀的进度。还可以针对横截面进行组成分析（元素分析）。
局部腐蚀的形式，示例和原因
据说与腐蚀有关的许多问题是由于难以预测其开发率的地方发生的局部腐蚀引起的。同样，金属表面保护性涂层的损坏可能会导致局部腐蚀，从而导致局部损坏。
下面描述了局部腐蚀的典型形式和原因。
Intergranular corrosion
- A. Intergranular corrosion
- B.脱落
- 现象：由具有低腐蚀潜力的晶粒边界上的杂质和夹杂物引起的腐蚀。也可能发生晶间腐蚀导致晶粒掉落的脱落。
- Examples:这种现象发生在不锈钢或铝合金尚未得到适当或充分处理的位置。它也发生在受焊热影响的区域。
- 原因：
在材料方面：较低的晶界铬浓度，痕量成分的晶界隔离，晶界沉积等。
点缀
- A.点点
- B. Passivation film
- 现象：在非常有限的金属表面上发生的腐蚀，该腐蚀保持了被动状态（钝化膜），该腐蚀在小孔直径上深处进行。
- Examples:卤素离子（例如Cl-）局部损坏的钝化膜，导致孔的形状腐蚀。这是由金属不均匀性触发的，例如不锈钢和铝合金水溶液溶液中的非金属夹杂物。
- 原因：
On the environment side: Halogen ions, dissolved oxygen.
在材料方面：夹杂物，缺陷等。
缝隙腐蚀
- A.缝隙腐蚀
- B. Passivation film
- 现象：腐蚀是由于缝隙中缺乏溶解的氧，从而破坏了金属表面上的钝化膜，从而导致金属融化。
- Examples:This phenomenon occurs on stainless steel, aluminum, and titanium flange faces.
- 原因：
在结构/材料方面：缝隙结构，氧化尺度等。
在环境方面：卤素离子，溶解氧（生长阶段与点相同）。
Contact corrosion (bimetallic contact corrosion and galvanic corrosion)
- A.腐蚀部分
- B.基金
- C.贵金属
- 现象：由于具有不同电极电位的金属与在接触点上存在电解质溶液之间存在的接触，因此在碱金属上发生并促进了腐蚀。
- Examples:铝和铜之间的接触会腐蚀铝，而钢和不锈钢之间的接触将钢腐蚀。
- 原因：
On the material side: Contact between metals having different electric potentials.
应力腐蚀破裂
- 现象：拉伸应力（残余应力或外部载荷应力）引起的腐蚀，在局部损坏表面的保护涂层。浓度的腐蚀进展将导致破裂。
- 开裂形式的类型：应力腐蚀开裂公关的路线oceeds varies depending on the combination of metal and environment, there are also differences in cracking forms.
经晶体裂纹通过晶粒进行，而晶界裂纹则沿晶界进行。 - 原因：
经晶裂：包含，沉积物，表面涂层，材料缺陷等。
晶界裂纹：痕量元素的晶界，隔离，晶界铬排出的层，晶界沉积，晶界不规则等等。
腐蚀测试中解决问题的实际例子
由于可以根据腐蚀形式鉴定腐蚀的原因，因此使用显微镜的外观观察和详细观察对于腐蚀测试很重要。
Corroded parts have three dimensional shapes, so observation of corroded parts using conventional microscopes have various problems, for example, in adjusting the focus and extracting lighting conditions. Also, it is sometimes difficult to observe intergranular corrosion or corrosion cracking in detail due to insufficient resolution.
钥匙's VHX Series ultra-high-definition 4K Digital Microscope uses a high-resolution lens, a 4K CMOS, and a specially designed observation system. These and other built-in technologies not only solve problems with conventional microscopes but also enable accurate and quick observation and analysis with simple operation using high-resolution 4K images.
本节介绍了多功能VHX系列4K数字显微镜的应用示例，重点是解决腐蚀零件分析时传统显微镜的问题。
Observation of grain boundaries using high-accuracy, high-resolution images
显微镜的常规问题
高磁化观察的分辨率不足可阻止对晶界和那里发生的晶间腐蚀的明确观察。
使用VHX系列4K数字显微镜
The high-resolution lens and 4K CMOS enable observation using high-resolution, high-definition 4K images even in high-magnification observation of grain boundaries.
因此，可以通过清晰的图像详细观察晶间腐蚀，脱落和应力腐蚀开裂（经晶裂和晶界开裂）。
Fully focused observation of the entirety of a three-dimensional corroded part
显微镜的常规问题
Because corroded parts are three dimensional, only a part of the target can be brought into focus at a time due to the limitations of the depth of field of conventional microscopes, which prevents observation while tracking the entire image. This causes problems such as different evaluation results occurring between operators and details being overlooked.
使用VHX系列4K数字显微镜
The high-resolution lens that enables a deep depth of field and detailed observation, the 4K CMOS, and the real-time depth composition make it possible to instantaneously obtain a high-definition 4K image, with the entire target fully focused, through simple operation.
无需调整每个观察点的焦点，从而可以从任何角度进行快速观察。
左：正常/右：深度组成（200x）
左：正常/右：深度组成（150x）
观察腐蚀模式而无需照明调整
显微镜的常规问题
观察金属腐蚀零件使得很难提取照明条件，并且需要在观察腐蚀模式之前重复调整照明条件。结果是这种观察需要大量时间和精力。
使用VHX系列4K数字显微镜
通过按下按钮，多光功能可以快速获取来自各个方向的照明的多个图像。通过简单地选择最适合观察的图像，用户可以使用清晰的图像执行观察。
该功能消除了通常花在提取照明条件上的时间和精力，并在最佳照明下使用高清图像进行快速观察。
Furthermore, other multi-lighting image data is automatically saved even after the observation image is selected, so observation can be performed under different lighting conditions simply by reselecting an image. This function can eliminate the time and effort that were conventionally required to set the sample on the stage once more and to readjust lighting.
A Microscope That Changes Corrosion Tests
In addition to the functions introduced here, the VHX Series high-definition 4K Digital Microscope is equipped with many more useful functions for analyses and tests.
除了对腐蚀零件的高清观察外，VHX系列无缝地对亚微米顺序和自动面积测量值高度准确地测量了高度准确的2D和3D测量，这对于定量晶粒边界的定量评估很有用。
此外，使用VHX系列，单个单元是完成观察，测量，分析和报告所需的。
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