Solve Corrosion Problems in Demanding Environments

254SMO seamless stainless steel pipe
254SMO is a martensitic free working chromium steel alloy, which is commonly considered as the first free working stainless steel. It has the highest machinability among any stainless steel, about 85% of that of free machined carbon steel. Martensitic stainless steel is designed to be hardened through heat treatment and has corrosion resistance. Although the corrosion resistance of 416 alloy and other martensitic stainless steels is not as good as austenitic or ferritic stainless steels, it still exhibits good corrosion resistance, oxidation resistance, and high strength under hardening and tempering conditions.

Advanced Manufacturing and Technical Superiority

Our 302 seamless stainless steel pipes feature precise chemical composition with chromium content of 24-26% and nickel content of 6-8%, providing enhanced corrosion resistance compared to standard 304 stainless steel. The seamless construction ensures uniform wall thickness and superior pressure containment capabilities. Available in thicknesses from 0.6mm to 6.0mm and diameters from 4mm to 200mm, these pipes maintain excellent mechanical properties with tensile strength ≥795 MPa and yield strength ≥550 MPa. The hot rolling and cold rolling production technologies guarantee dimensional accuracy and surface quality.

Easy Installation and Customization Options

302 seamless stainless steel pipes offer excellent fabrication characteristics with easy cutting, welding, and forming capabilities. Standard lengths of 1-6 meters are available with custom cutting services to meet specific project requirements. Multiple surface finishes including bright polishing, NO.4, BA, and matt surfaces provide flexibility for different aesthetic and functional needs. Edge grinding and trimming services ensure perfect fitment during installation. The pipes' excellent elongation properties (≥15%) allow for bending and shaping without compromising structural integrity.

Quality Assurance and Global Compliance

Every 302 seamless stainless steel pipe undergoes rigorous quality control and testing to ensure compliance with international standards including ASTM, AISI, JIS, GB, DIN, and EN. Our manufacturing facilities maintain ISO, SGS, and BV certifications, guaranteeing consistent quality across all production batches. With comprehensive material traceability and test certificates provided with each shipment, you can trust the reliability and performance of our products. Our experienced technical support team assists with material selection and application engineering for optimal project outcomes.

https://www.youtube.com/watch?v=rPBS9YEkjkU

What is stainless steel
什么是不锈钢

Stainless steel is an alloy of Iron with a minimum of 10.5% Chromium. Chromium produces a thin layer of oxide on the surface of the steel known as the ‘passive layer‘. This prevents any further corrosion of the surface. Increasing the amount of Chromium gives an increased resistance to corrosion.
不锈钢是铬含量至少为 10.5% 的铁合金。铬在钢表面产生一层薄薄的氧化物，称为“ 钝化层 ”。这可以防止表面进一步腐蚀。增加铬的含量可以提高耐腐蚀性。

Stainless steel also contains varying amounts of Carbon, Silicon and Manganese. Other elements such as Nickel and Molybdenum may be added to impart other useful properties such as enhanced formability and increased corrosion resistance.
不锈钢还含有不同数量的碳、硅和锰。可以添加其他元素，如镍和钼，以赋予其他有用的特性，例如增强的成型性和  更高的耐腐蚀性。

When was stainless steel discovered ?
不锈钢是什么时候发现的？

There is a widely held view that stainless steel was discovered in 1913 by Sheffield metallurgist Harry Brearley. He was experimenting with different types of steel for weapons and noticed that a 13% Chromium steel had not corroded after several months. However, the picture is much more complex than this. For a comprehensive view read The Discovery of Stainless Steel.
人们普遍认为不锈钢是由谢菲尔德冶金学家哈里·布雷尔利 （Harry Brearley） 于 1913 年发现的。他正在试验不同类型的武器钢，并注意到 13% 铬钢在几个月后没有腐蚀。然而，情况远比这复杂得多。如需全面了解，请阅读 《不锈钢的发现 》。

1. Ferritic – These steels are based on Chromium with small amounts of Carbon, usually less than 0.10%. These steels have a similar microstructure to carbon and low alloy steels. They are usually limited in use to relatively thin sections due to lack of toughness in welds. However, where welding is not required they offer a wide range of applications. They cannot be hardened by heat treatment. High Chromium steels with additions of Molybdenum can be used in quite aggressive conditions such as sea water. Ferritic steels are also chosen for their resistance to stress corrosion cracking. They are not as formable as austenitic stainless steels. They are magnetic.
铁素体 – 这些钢以铬为基础，碳含量很少，通常低于 0.10%。这些钢具有与碳钢和低合金钢相似的微观结构。由于焊缝缺乏韧性，它们通常仅限于相对较薄的部分使用。然而，在不需要焊接的地方，它们提供了广泛的应用。它们不能通过热处理硬化。添加钼的高铬钢可用于海水等非常恶劣的条件下。选择铁素体钢也是因为它们抗应力腐蚀开裂。它们不像奥氏体不锈钢那样可成型。它们是磁性的。

2. Austenitic – These steels are the most common. Their microstructure is derived from the addition of Nickel, Manganese and Nitrogen. It is the same structure as occurs in ordinary steels at much higher temperatures. This structure gives these steels their characteristic combination of weldability and formability. Corrosion resistance can be enhanced by adding Chromium, Molybdenum and Nitrogen. They cannot be hardened by heat treatment, but have the useful property of being able to be work hardened to high strength levels whilst retaining a useful level of ductility and toughness. Standard austenitic steels are vulnerable to stress corrosion cracking. Higher nickel austenitic steels have increased resistance to stress corrosion cracking. They are nominally non-magnetic, but usually exhibit some magnetic response depending on the composition and the work hardening of the steel.
奥氏体 – 这些钢是最常见的。它们的微观结构源自镍、锰和氮的添加。它与在更高温度下的普通钢中出现的结构相同。这种结构赋予这些钢具有可焊性和成型性的特征组合。通过添加铬、钼和氮气可以增强耐腐蚀性。它们不能通过热处理硬化，但具有能够加工硬化到高强度水平的有用特性，同时保持有用的延展性和韧性水平。标准奥氏体钢容易受到应力腐蚀开裂的影响。高镍奥氏体钢具有更高的抗应力腐蚀开裂能力。它们名义上是非磁性的，但通常表现出一些磁响应，具体取决于钢的成分和加工硬化。

3. Martensitic – These steels are similar to ferritic steels in being based on Chromium, but have higher Carbon levels, up as high as 1%. This allows them to be hardened and tempered much like carbon and low-alloy steels. They are used where high strength and moderate corrosion resistance is required. They are a little more common in long products than in sheet and plate form. They have generally low weldability and formability. They are magnetic.
马氏体 – 这些钢与铁素体钢相似，以铬为基础，但碳含量更高，高达 1%。这使得它们能够像碳钢和低合金钢一样进行硬化和回火。它们用于需要高强度和中等耐腐蚀性的地方。它们在长产品中比在片材和板材中更常见。它们通常具有较低的可焊性和成型性。它们是磁性的。

4. Duplex – These steels have a microstructure which is approximately 50% ferritic and 50% austenitic. This gives them a higher strength than either ferritic or austenitic steels. They are resistant to stress corrosion cracking. So called “lean duplex” steels are formulated to have comparable corrosion resistance to standard austenitic steels, but with enhanced strength and resistance to stress corrosion cracking. “Superduplex” steels have enhanced strength and resistance to all forms of corrosion compared to standard austenitic steels. They are weldable, but need care in selection of welding consumables and heat input. They have moderate formability. They are magnetic, but not so much as the ferritic, martensitic and PH grades, due to the 50% austenitic phase.
双相 – 这些钢的微观结构约为 50% 的铁素体和 50% 的奥氏体。这使它们具有比铁素体或奥氏体钢更高的强度。它们具有抗应力腐蚀开裂的能力。所谓的“精益双相”钢的配方具有与标准奥氏体钢相当的耐腐蚀性，但具有增强的强度和抗应力腐蚀开裂性。与标准奥氏体钢相比，“超级双相”钢具有增强的强度和对各种形式的腐蚀的抵抗力。它们是可焊接的，但在选择焊材和热输入时需要小心。它们具有适度的成型性。它们具有磁性，但由于奥氏体相为 50%，因此不如铁素体、马氏体和 PH 等级。

5. Precipitation hardening (PH) – These steels can develop very high strength by adding elements such as Copper, Niobium and Aluminium to the steel. With a suitable “aging” heat treatment, very fine particles form in the matrix of the steel which imparts strength. These steels can be machined to quite intricate shapes requiring good tolerances before the final aging treatment as there is minimal distortion from the final treatment. This is in contrast to conventional hardening and tempering in martensitic steels where distortion is more of a problem. Corrosion resistance is comparable to standard austenitic steels like 1.4301 (304).
沉淀硬化 （PH） – 这些钢可以通过在钢中添加铜、铌和铝等元素来产生非常高的强度。通过适当的“时效”热处理，钢基体中会形成非常细的颗粒，从而赋予强度。这些钢可以加工成非常复杂的形状，在最终时效处理之前需要良好的公差，因为最终处理的变形最小。这与马氏体钢的传统硬化和回火形成鲜明对比，在马氏体钢中，变形是一个更大的问题。耐腐蚀性可与 1.4301 （304） 等标准奥氏体钢相媲美

What is stainless steel used for
不锈钢有什么用

Stainless steels of various kinds are used in thousands of applications. The following gives just a flavour of the full range:
各种不锈钢被用于数千种应用。以下仅给出了全系列的风味：

Domestic – cutlery, sinks, saucepans, washing machine drums, microwave oven liners, razor blades
家用 – 餐具、水槽、平底锅、洗衣机滚筒、微波炉内衬、剃须刀片

Architectural/Civil Engineering – cladding, handrails, door and window fittings, street furniture, structural sections, reinforcement bar, lighting columns, lintels, masonry supports
建筑/土木工程 – 覆层、扶手、门窗配件、街道设施、结构部分、钢筋、照明柱、门楣、砖石支架

Transport – exhaust systems, car trim/grilles, road tankers, ship containers, ships chemical tankers, refuse vehicles
运输 – 排气系统、汽车装饰/格栅、公路油罐车、船舶集装箱、船舶化学品罐车、垃圾车

Chemical/Pharmaceutical – pressure vessels, process piping.
化工/制药 – 压力容器、工艺管道。

Oil and Gas – platform accommodation, cable trays, subsea pipelines.
石油和天然气 – 平台住宿、电缆桥架、海底管道。

Medical – Surgical instruments, surgical implants, MRI scanners.
医疗 – 手术器械、手术植入物、MRI 扫描仪。

Food and Drink – Catering equipment, brewing, distilling, food processing.
食品和饮料 – 餐饮设备、酿造、蒸馏、食品加工。

Water – Water and sewage treatment, water tubing, hot water tanks.
水 – 水和污水处理、水管、热水箱。

General – springs, fasteners (bolts, nuts and washers), wire.
一般 – 弹簧、紧固件（螺栓、螺母和垫圈）、电线。

How do I choose which stainless steel to use?
如何选择使用哪种不锈钢？

Most decisions about which steel to use are based on a combination of the following factors:
大多数关于使用哪种钢材的决定都是基于以下因素的组合：

1. What is the corrosive environment? – Atmospheric, water, concentration of particular chemicals, chloride content, presence of acid.
什么是腐蚀性环境？– 大气、水、特定化学物质的浓度、氯化物含量、酸的存在。

2. What is the temperature of operation? – High temperatures usually accelerate corrosion rates and therefore indicate a higher grade. Low temperatures will require a tough austenitic steel.
作温度是多少？– 高温通常会加速腐蚀速度，因此表明等级较高。低温需要坚韧的奥氏体钢。

3. What strength is required? – Higher strength can be obtained from the austenitic, duplex, martensitic and PH steels. Other processes such as welding and forming often influence which of these is most suitable. For example, high strength austenitic steels produced by work hardening would not be suitable where welding was necessary as the process would soften the steel.
需要什么强度？– 奥氏体钢、双相钢、马氏体钢和 PH 钢可以获得更高的强度。焊接和成型等其他工艺通常会影响其中哪一个最合适。例如，通过加工硬化生产的高强度奥氏体钢不适合需要焊接的地方，因为该工艺会软化钢。

4. What welding will be carried out? – Austenitic steels are generally more weldable than the other types. Ferritic steels are weldable in thin sections. Duplex steels require more care than austenitic steels, but are now regarded as fully weldable. Martensitic and PH grades are less weldable.
将进行什么焊接？– 奥氏体钢通常比其他类型的钢更易于焊接。铁素体钢可焊接成薄片。双相钢比奥氏体钢需要更多的小心，但现在被认为是完全可焊接的。马氏体和 PH 牌号的可焊性较差。

5. What degree of forming is required to make the component? – Austenitic steels are the most formable of all the types being able to undergo a high degree of deep drawing or stretch forming. Generally, ferritic steels are not as formable, but can still be capable of producing quite intricate shapes. Duplex, martensitic and PH grades are not particularly formable.
制造组件需要什么程度的成型？– 奥氏体钢是所有类型中最易成型的，能够进行高度的深冲或拉伸成型。一般来说，铁素体钢的成型性不高，但仍然能够生产出相当复杂的形状。双相、马氏体和 PH 牌号不是特别容易成型。

6. What product form is required? – Not all grades are available in all product forms and sizes, for example sheet, bar, tube. In general, the austenitic steels are available in all product forms over a wide range of dimensions. Ferritics are more likely to be in sheet form than bar. For martensitic steels, the reverse is true.
需要什么产品形式？– 并非所有牌号都适用于所有产品形式和尺寸，例如片材、棒材、管材。一般来说，奥氏体钢有各种尺寸的所有产品形式。铁素质更有可能是片状形式而不是棒状。对于马氏体钢，情况恰恰相反。

7. What are the customer’s expectations of the performance of the material? – This is an important consideration often missed in the selection process. Particularly, what are the aesthetic requirements as compared to the structural requirements? Design life is sometimes specified, but is very difficult to guarantee.
客户对材料性能的期望是什么？– 这是选择过程中经常忽略的重要考虑因素。特别是，与结构要求相比，美学要求是什么？有时会指定设计寿命，但很难保证。

8. There may also be special requirements such as non-magnetic properties to take into account.
还可能有特殊要求，例如非磁性需要考虑。

9. It must also be borne in mind that steel type alone is not the only factor in material selection. Surface finish is at least as important in many applications, particularly where there is a strong aesthetic component. See Importance of Surface Finish.
还必须记住，钢种并不是材料选择的唯一因素。表面光洁度在许多应用中至少同样重要，特别是在具有强烈美学成分的情况下。请参阅表面光洁度的重要性 。

10. Availability. There may be a perfectly correct technical choice of material which cannot be implemented because it is not available in the time required.
可用性。可能有一个完全正确的材料技术选择，但由于在所需的时间内无法获得而无法实施。

11. Cost. Sometimes the correct technical option is not finally chosen on cost grounds alone. However, it is important to assess cost on the correct basis. Many stainless steel applications are shown to be advantageous on a life cycle cost basis rather than initial cost. See Life Cycle Costing.
成本。有时，最终不会仅仅出于成本原因选择正确的技术选项。但是，在正确的基础上评估成本很重要。许多不锈钢应用在生命周期成本基础上比初始成本更有利。 请参阅生命周期成本核算 。

The final choice will almost certainly be in the hands of a specialist, but their task can be helped by gathering as much information about the above factors. Missing information is sometimes the difference between a successful and unsuccessful application. See also General principles for selection of stainless steels
最终的选择几乎肯定会掌握在专家手中，但可以通过收集有关上述因素的尽可能多的信息来帮助完成他们的任务。缺少信息有时是成功与否的区别。另见 不锈钢选择的一般原则

Does stainless steel corrode?
不锈钢会腐蚀吗？

Although stainless steel is much more resistant to corrosion than ordinary carbon or alloy steels, in some circumstances it can corrode. It is ‘stain-less’ not ‘stain-impossible’. In normal atmospheric or water based environments, stainless steel will not corrode as demonstrated by domestic sink units, cutlery, saucepans and work-surfaces.
尽管不锈钢比普通碳钢或合金钢更耐腐蚀，但在某些情况下它会腐蚀。它是“无染色”，而不是“不可能染色”。在正常的大气或水基环境中，不锈钢不会像家用水槽、餐具、平底锅和工作台面那样腐蚀。

In more aggressive conditions, the basic types of stainless steel may corrode and a more highly alloyed stainless steel can be used. See Corrosion Mechanisms in Stainless Steel
在更恶劣的条件下，基本类型的不锈钢可能会腐蚀，可以使用合金含量更高的不锈钢。查看不锈钢的腐蚀机制

What Forms of Corrosion can Occur in Stainless Steels
不锈钢会发生哪些形式的腐蚀

The most common forms of corrosion in stainless steel are:
不锈钢最常见的腐蚀形式是：

1. Pitting corrosion – The passive layer on stainless steel can be attacked by certain chemical species. The chloride ion Cl- is the most common of these and is found in everyday materials such as salt and bleach. Pitting corrosion is avoided by making sure that stainless steel does not come into prolonged contact with harmful chemicals or by choosing a grade of steel which is more resistant to attack. The pitting corrosion resistance can be assessed using the Pitting Resistance Equivalent Number calculated from the alloy content.
点蚀  – 不锈钢上的钝化层可能会受到某些化学物质的侵蚀。氯离子 Cl- 是其中最常见的，存在于盐和漂白剂等日常材料中。通过确保不锈钢不会与有害化学物质长时间接触或选择更耐侵蚀的钢种来避免点蚀。可以使用根据合金含量计算的抗点蚀当量值  来 评估耐点蚀性。

2. Crevice corrosion – Stainless steel requires a supply of oxygen to make sure that the passive layer can form on the surface. In very tight crevices, it is not always possible for the oxygen to gain access to the stainless steel surface thereby causing it to be vulnerable to attack. Crevice corrosion is avoided by sealing crevices with a flexible sealant or by using a more corrosion resistant grade.
缝隙腐蚀  – 不锈钢需要氧气供应以确保表面可以形成钝化层。在非常狭窄的缝隙中，氧气并不总是能够进入不锈钢表面，从而导致其容易受到攻击。通过使用柔性密封剂或使用更耐腐蚀的等级来避免缝隙腐蚀。

3. General corrosion – Normally, stainless steel does not corrode uniformly as do ordinary carbon and alloy steels. However, with some chemicals, notably acids, the passive layer may be attacked uniformly depending on concentration and temperature and the metal loss is distributed over the entire surface of the steel. Hydrochloric acid and Sulphuric acid at some concentrations are particular aggressive towards stainless steel.
一般腐蚀  – 通常，不锈钢不会像普通碳钢和合金钢那样均匀腐蚀。然而，对于某些化学品，特别是酸，钝化层可能会根据浓度和温度受到均匀的侵蚀，并且金属损失分布在钢 的整个表面。某些浓度的盐酸和  硫酸  对不锈钢特别具有腐蚀性。

4. Stress corrosion cracking (SCC) – This is a relatively rare form of corrosion which requires a very specific combination of tensile stress, temperature and corrosive species, often the chloride ion, for it to occur. Typical applications where SCC can occur are hot water tanks and swimming pools. Another form known as sulphide stress corrosion cracking (SSCC) is associated with hydrogen sulphide in oil and gas exploration and production.
应力腐蚀开裂 （SCC） – 这是一种相对罕见的腐蚀形式，需要拉伸应力、温度和腐蚀性物质（通常是氯离子）的非常特殊的组合才能发生。可能发生 SCC 的典型应用是  热水箱  和  游泳池 。另一种形式称为硫化物应力腐蚀开裂 （SSCC），与石油和天然气勘探和生产中的硫化氢有关。

5. Intergranular corrosion – This is now quite a rare form of corrosion. If the Carbon level in the steel is too high, Chromium can combine with Carbon to form Chromium Carbide. This occurs at temperatures between about 450-850 deg C. This process is also called sensitisation and typically occurs during welding. The Chromium available to form the passive layer is effectively reduced and corrosion can occur. It is avoided by choosing a low carbon grade the so-called ‘L’ grades or by using a steel with Titanium or Niobium which preferentially combines with Carbon.
晶间腐蚀  – 这现在是一种非常罕见的腐蚀形式。如果钢中的碳含量过高，铬会与碳结合形成碳化铬。这发生在大约 450-850 摄氏度之间的温度下。这个过程也称为敏化，通常发生在焊接过程中。可用于形成钝化层的铬被有效减少，并可能发生腐蚀。通过选择低碳等级，即所谓的 “L”等级  或使用优先与碳结合的钛或铌钢来避免这种情况。

6. Galvanic corrosion – If two dissimilar metals are in contact with each other and with an electrolyte e.g. water or other solution, it is possible for a galvanic cell to be set up. This is rather like a battery and can accelerate corrosion of the less ‘noble’ metal. It can avoided by separating the metals with a non-metallic insulator such as rubber.
电偶腐蚀  – 如果两种不同的金属相互接触并与电解质（例如水或其他溶液）接触，则可以设置原电池。这很像电池，可以加速不太“贵重”金属的腐蚀。可以通过用橡胶等非金属绝缘体分离金属来避免这种情况。

What are the correct standards for stainless steel?
不锈钢的正确标准是什么？

The most common current European standards for stainless steel are:
目前最常见的欧洲不锈钢标准是：

These standards have replaced the old national standards and users are encouraged to use them. However, it is clear that the old standards are still used, not least because many existing drawings and company specifications refer to them. Therefore, it is still possible to come across standards such as:
这些标准已经取代了旧的国家标准，鼓励用户使用它们。然而，很明显，旧标准仍在使用，尤其是因为许多现有图纸和公司规范都引用了它们。因此，仍然有可能遇到以下标准：

BS 1449 and BS1501 for flat products
BS 1449 和 BS1501 适用于扁平产品

BS 970 for long products
BS 970 用于长产品

The US standards such as ASTM and ASME are very important and will never be replaced. Common standards are:
ASTM 和 ASME 等美国标准非常重要，永远不会被取代。常见标准有：

What surface finishes are available on stainless steels ?
不锈钢有哪些表面处理？

There are many different types of surface finish on stainless steel. Some of these originate from the mill, but many are applied later during processing, for example polished, brushed, blasted, etched and coloured finishes.
不锈钢有许多不同类型的表面光洁度。其中一些来自工厂，但许多是在加工过程中稍后应用的，例如抛光、拉丝、喷砂、蚀刻和彩色饰面。

The importance of surface finish in determining the corrosion resistance of the stainless steel surface cannot be overemphasised. A rough surface finish can effectively lower the corrosion resistance to that of a lower grade of stainless steel.
表面光洁度  在确定不锈钢表面耐腐蚀性方面的重要性怎么强调都不为过。粗糙的表面光洁度可以有效地将耐腐蚀性降低到较低等级的不锈钢。

The European standards for stainless steels have attempted to define the most common surface finishes. However, due to the proprietary nature of many suppliers’ finishes, it is unlikely that complete standardisation is possible. This is a summary of the most common types for each product form
欧洲不锈钢标准试图定义最常见的表面光洁度。然而，由于许多供应商饰面的专有性质，完全标准化的可能性不大。这是每种产品形式最常见类型的摘要

Common Surface Finishes for Flat Products from EN 10088-2 (for full list see Specifying finishes for stainless steel flat products (sheet and plate))
EN 10088-2 中扁平产品的常见表面处理（有关完整列表，请参阅指定不锈钢扁平产品 （板材和板材）的饰面）

Can I use stainless steel at low temperatures?
我可以在低温下使用不锈钢吗？

Austenitic stainless steels are extensively used for service down to as low as liquid helium temperature, (-269 deg. C). This is largely due to the lack of a clearly defined transition from ductile to brittle fracture in impact toughness testing.
奥氏体不锈钢广泛用于低至液氦温度（-269 摄氏度）的使用。这主要是由于在冲击韧性测试中缺乏明确定义的从延性断裂到脆性断裂的过渡。

Toughness of metals is most often measured in the test laboratory by impacting a small sample with a swinging hammer. The distance which the hammer swings after impact is a measure of the toughness. The shorter the distance, the tougher the steel, as the kinetic energy of the hammer is absorbed by the sample. Toughness is measured in Joules, (J). Minimum values of toughness are specified for different applications. A value of 40 J is regarded as reasonable for most service conditions.
金属的韧性通常在测试实验室中通过用摆动的锤子撞击小样品来测量。击锤在冲击后摆动的距离是韧性的衡量标准。距离越短，钢材越坚韧，因为锤子的动能被样品吸收。韧性以焦耳 （J） 为单位测量。针对不同的应用规定了韧性的最小值。对于大多数服务条件，40 J 的值被认为是合理的。

Steels with ferritic or martensitic structures show a sudden change from ductile, (safe), to brittle, (unsafe), fracture over a small temperature difference. Even the best of these steels show this behaviour at temperatures higher than -100 deg. C and in many cases only just below zero.
具有铁素体或马氏体结构的钢在很小的温差下表现出从延展性（安全）到脆性（不安全）断裂的突然变化。即使是这些钢中最好的钢材，在高于 -100 摄氏度的温度下也表现出这种行为，在许多情况下仅略低于零。

In contrast austenitic steels only show a gradual fall in the impact toughness value and are still well above 100 J at -196 deg. C. See Selection of stainless steels for cryogenic applications.
相比之下，奥氏体钢的冲击韧性值仅逐渐下降，并且在-196°C 时仍远高于 100 J。请参阅用于低温应用的不锈钢选择 。

Another factor in affecting the choice of steel at low temperature is the ability to resist transformation from austenite to martensite. This factor is discussed in more detail in Composition effects on the magnetic permeability of austenitic stainless steels.
影响低温钢选择的另一个因素是抵抗从奥氏体到马氏体转变的能力。该因素在成分对奥氏体不锈钢磁导率的影响中进行了更详细的讨论。

Can I use stainless steel at high temperatures ?
我可以在高温下使用不锈钢吗？

Various types of stainless steel are used across the whole temperature range from ambient to 1100 deg C. The choice of grade depends on several factors:
在从环境温度到 1100 摄氏度的整个温度范围内使用各种类型的不锈钢。等级的选择取决于几个因素：

1. Maximum temperature of operation
最高工作温度

2. Time at temperature, cyclic nature of process
温度下的时间，过程的循环性

3. Type of atmosphere, oxidising, reducing, sulphidising, carburising.
气氛类型， 氧化 、还原、  硫化 、渗碳。

4. Strength requirement  强度要求

In the European standards, a distinction is made between stainless steels and heat-resisting steels. However, this distinction is often blurred and it is useful to consider them as one range of steels.
在欧洲标准中，不锈钢和耐热钢是有区别的。然而，这种区别通常很模糊，将它们视为一个钢种是有用的。

Increasing amounts of Chromium and Silicon impart greater oxidation resistance. Increasing amounts of Nickel impart greater carburisation resistance.
铬和硅含量的增加赋予了更高的抗氧化性。镍含量的增加赋予了更大的渗碳阻力。

Is stainless steel non-magnetic?
不锈钢是无磁性的吗？

It is commonly stated that “stainless steel is non-magnetic”. This is not strictly true and the real situation is rather more complicated. The degree of magnetic response or magnetic permeability is derived from the microstructure of the steel. A totally non-magnetic material has a relative magnetic permeability of 1. Austenitic structures are totally non-magnetic and so a 100% austenitic stainless steel would have a permeability of 1. In practice this is not always achieved, in fact it is rarer than is commonly thought. Instead there often tends to be a small amount of ferrite and/or martensite in the steel, and so permeability values are often slightly above 1. Typical values for standard austenitic stainless steels can be in the order of 1.05 – 1.1. See Composition effects on the magnetic permeability of austenitic stainless steels
人们常说“不锈钢是无磁性的”。严格来说，这并不是真的，真实情况要复杂得多。磁响应程度或磁导率源自钢的微观结构。完全非磁性材料的相对磁导率为 1。奥氏体结构是完全非磁性的，因此 100% 奥氏体不锈钢的磁导率为 1。在实践中，这并不总是能实现，事实上，它比通常认为的要罕见。相反，钢中通常存在少量铁素体和/或马氏体，因此磁导率值通常略高于 1。标准奥氏体不锈钢的典型值约为 1.05 – 1.1。参见成分对奥氏体不锈钢磁导率的影响

It is possible for the magnetic permeability of austenitic steels to be changed during processing. For example, cold work and welding are liable to increase the amount of martensite and ferrite, respectively, in the steel. A familiar example is in a stainless steel sink where the flat drainer has little magnetic response whereas the pressed bowl has a higher response due to the formation of martensite particularly in the corners.
奥氏体钢的磁导率在加工过程中可能会发生变化。例如， 冷作和焊接容易分别增加钢中马氏体和铁素体的含量。一个熟悉的例子是在不锈钢水槽中，扁平沥水器几乎没有磁响应，而压制碗由于马氏体的形成，特别是在角落中具有更高的响应。

In practical terms, austenitic stainless steels are used for “non-magnetic” applications, for example magnetic resonance imaging (MRI). In these cases, it is often necessary to agree a maximum magnetic permeability between customer and supplier. It can be as low as 1.004.
实际上，奥氏体不锈钢用于“非磁性”应用，例如磁共振成像 （MRI）。在这些情况下，通常需要在客户和供应商之间商定最大磁导率。它可以低至 1.004。

Martensitic, ferritic, duplex and precipitation hardening steels are magnetic.
马氏体、铁素体、双相和沉淀硬化钢具有磁性 。

What is 'multiple certification'?
什么是“多重认证”？

This is where a batch of steel meets more than one specification or grade. It is a way of allowing melting shops to produce stainless steel more efficiently by restricting the number of different types of steel. The chemical composition and mechanical properties of the steel can meet more than one grade within the same standard, or across a number of standards. This also allows stockholders to minimise stock levels.
这是一批钢材满足多个规格或牌号的地方。这是一种通过限制不同类型钢材的数量，让熔炼车间更有效地生产不锈钢的方法。钢的化学成分和机械性能可以满足同一标准内或多个标准中的多个等级。这也允许股东最大限度地降低库存水平。

For example, it is common for 1.4401 and 1.4404, (316 and 316L), to be dual certified – that is the carbon content is less than 0.030%. Steel certified to both European and US standards is also common.
例如，1.4401 和 1.4404（316 和 316L）通常获得双重认证——即碳含量小于 0.030%。通过欧洲和美国标准认证的钢材也很常见。