大多數人認為不鏽鋼（gāng）是絕（jué）對不會生鏽的，而生鏽的就不是不鏽鋼了。其實，一些含鎳低（dī）的不鏽鋼材質在一定的條件下也會生鏽的。不鏽鋼方管具（jù）有抵（dǐ）抗大（dà）氣氧（yǎng）化的能力，同時也具有在含酸、堿、鹽的（de）介質中耐腐蝕的能力。但其抗腐蝕能力的大（dà）小（xiǎo）是隨其（qí）鋼質本身化學組成、加（jiā）互狀態、使用條件及環境介質類（lèi）型而改變的。因此，不（bú）是任何（hé）一種不鏽鋼（gāng），在任何環境下都能耐腐蝕不生鏽。
Most people think that stainless steel will never rust, but stainless steel will not rust. In fact, some stainless steel materials with low nickel content will rust under certain conditions. Stainless steel square tube has the ability to resist atmospheric oxidation, but also has the ability to resist corrosion in medium containing acid, alkali and salt. However, the corrosion resistance of the steel varies with its chemical composition, additive state, service conditions and the type of environmental medium. Therefore, not any stainless steel, in any environment can resist corrosion and rust.
Square tube
不鏽鋼是靠其表麵形成的（de）一層（céng）極薄（báo）而堅固細（xì）密的穩（wěn）定（dìng）的富鉻氧化膜來防止氧（yǎng）原子滲入氧化，而獲得抗鏽蝕的能力。該薄膜如果（guǒ）遭到破壞，不鏽鋼方（fāng）管就會失去抗鏽能力。日常中多見的破壞方式有（yǒu）如下四種：
Stainless steel is formed by a very thin, solid, compact and stable chromium-rich oxide film on its surface to prevent oxygen atoms from penetrating into oxidation, and to obtain the ability to resist corrosion. If the film is destroyed, the stainless steel square pipe will lose its rust resistance. There are four common ways of destruction in daily life:
（一）不鏽鋼方管表麵粘附有機物汁液（yè），在有（yǒu）水氧（yǎng）情況下，構成有機酸，長時間（jiān）則有機酸對（duì）金屬表麵的腐蝕。
(1) The surface of stainless steel square tubes is adhered with organic juice, which forms organic acids in the presence of water and oxygen, and corrodes the metal surface for a long time.
（二）在有汙染的空氣中，遇（yù）冷（lěng）凝（níng）水，形成（chéng）硫酸、硝酸、醋酸液點，引起化學腐蝕。
(2) In polluted air, when it encounters condensate water, it forms sulfuric acid, nitric acid and acetic acid liquid points, which cause chemical corrosion.
（三）不鏽鋼方管表（biǎo）麵存積著含有其他金（jīn）屬元素的粉（fěn）塵或異類金屬顆粒的附著（zhe）物，在潮濕的空氣中，附著物與不鏽鋼間的冷凝水（shuǐ），將二者（zhě）連成一個微電（diàn）池，引發了電化學（xué）反應，保護膜受到破壞，稱之謂電化學腐蝕。
(3) The surface of stainless steel square tubes contains dust containing other metal elements or adhesives of different metal particles. In humid air, the adhesives and the condensate water between the adhesives and stainless steel connect the two into a micro-battery, which causes electrochemical reaction and damages the protective film. It is called electrochemical corrosion.
（四）不鏽鋼方管表麵粘附含有（yǒu）酸、堿、鹽（yán）類物質，引起局部腐蝕。
(4) The adherence of stainless steel square tubes to the surface contains acids, alkalis and salts, which causes local corrosion.
