对于不锈钢制品，比如电动伸缩门，大多数人认为它不会生锈。这是一种比较片面的看法。不锈钢的抗腐蚀能力是很强，但也与所环境有很大的关系，如空气湿度、空气温度、流速、流动方向、空气中杂质的成分和数量等。
For stainless steel products, such as electric retractable doors, most people believe that they will not rust. This is a relatively one-sided view. The corrosion resistance of stainless steel is very strong, but it is also closely related to the environment, such as air humidity, air temperature, flow rate, flow direction, composition and quantity of impurities in the air, etc.
1、含有其他金属元素的粉尘或异种金属颗粒的附着物存放在不锈钢表面。在潮湿的空气中，附件与不锈钢之间的冷凝水将它们连接成一个微型电池，导致电化学反应并损坏保护膜，称为电化学腐蚀。
1. Dust containing other metal elements or attachments of dissimilar metal particles are stored on the surface of stainless steel. In humid air, the condensed water between the accessories and stainless steel connects them into a miniature battery, causing electrochemical reactions and damaging the protective film, known as electrochemical corrosion.
2、不锈钢表面附着有机汁液（如食物汁液、唾液等），在有水和氧气存在的情况下形成有机酸，长期对金属表面形成有机酸的腐蚀.
2. Organic juices (such as food juices, saliva, etc.) adhere to the surface of stainless steel, forming organic acids in the presence of water and oxygen, and long-term corrosion of metal surfaces by organic acids
3、在被污染的空气（含有大量硫化物、氧化物和氧化氢的气氛）中，在冷凝液存在下形成硝酸和醋酸液点，引起化学腐蚀。
3. In polluted air (containing a large amount of sulfides, oxides, and hydrogen oxide), nitric acid and acetic acid liquid points are formed in the presence of condensate, causing chemical corrosion.
4、不锈钢表面的附着物含有酸、碱、盐类物质（如装饰墙的碱水、石灰水喷雾计量），造成局部腐蚀。
4. The attachments on the stainless steel surface contain acid, alkali and salt substances (such as alkali water and lime water spray metering of decorative walls), causing local corrosion.
