听说镍基合金高温下对氢脆敏感 是真的吗
以百度 谷歌 必应 没找到
求复合一下要求的合金或金属 不会或者几乎不会出现“氢脆效应的合金或金属”可以用于涡轮泵或者燃烧室 (高熔点 有一定强度) 感谢
以百度 谷歌 必应 没找到
求复合一下要求的合金或金属 不会或者几乎不会出现“氢脆效应的合金或金属”可以用于涡轮泵或者燃烧室 (高熔点 有一定强度) 感谢
[修改于 2 年前 - 2023/01/29 20:54:44]
听说镍基合金高温下对氢脆敏感 是真的吗
听说铜镍合金不会
那钛合金 和镍基高温合金(单晶)
是否会出现氢脆 304/316不锈钢呢
ISO/TR 15916:2015 中关于氢脆现象的定义如下:
hydrogen embrittlement
Deleterious changes in the ductility properties of a metal that exposure to hydrogen can produce
金属暴露于氢气中,会导致其延展特性的有害变化
可能发生氢脆的金属,最常见的是钢材,其他金属如铁,镍,钴,钛,以及这些金属的合金都可能发生氢脆。铜,铝和不锈钢相对更不容易发生氢脆。
有一系列因素可能影响氢脆,例如环境温度和压力;氢的纯度,浓度和暴露时间;金属的内部应力,物理与机械特性,微结构,表面条件;以及材料中裂口的情况等等。
氢脆最容易发生在室温条件下,大多数金属在温度超过150度时不会发生氢脆。不过要注意区分氢脆现象与钢材在温度超过200度时出现的高温氢攻击现象(HTHA, High Temperature Hydrogen Attach)。氢脆是氢原子在钢材表面渗透,在表面的缺陷或其他应力中心处形成局部的塑性形变,而HTHA的机理是在高温下氢原子与钢材中的碳反应生成甲烷的过程。
高强度钢相比低强度钢,由于内部应力(张力)更大,更容易发生氢脆。
氢脆是由于氢原子的渗透而产生的,处于分子状态的氢气并不会导致氢脆。纯净的氢气是分子氢,而不纯净的氢气,比如其中含有的硫化氢杂质更容易分解出氢原子。
使金属产生氢脆的氢原子有两个主要来源,一是金属表面直接暴露于氢气,比如高压储氢容器,输氢管路。二是各种电化学反应产生的氢原子,包括各种使用酸的表面加工工艺(比如酸洗,刻蚀和清洁),腐蚀(比如阴极保护和碱性腐蚀)和电镀。此外金属加工也可能使氢原子进入金属内部,比如熔融或焊接时由于环境的湿度而产生的原子氢。因此氢脆现象并不仅仅是与直接接触氢的金属(比如储氢容器,输氢管路)有关的问题,而是金属材料科学的一个普遍问题。
防止氢脆危害的措施
ISO/TR 15916:2015中介绍了一些防止或减轻氢脆危害的可能措施:
限制材料的强度等级
降低材料应用中应力的等级
最小化残余应力
正火或完全退火冷加工材料
避免或最小化在操作过程中(比如冷弯成形)的冷态塑性变形
避免频繁的加载循环,以防止零部件的局部疲劳(氢可以加速和传播初始微小的疲劳裂痕)
使用抗氢脆的奥氏体钢(austenitic stainless steels)(奥氏体钢在低温下具有非常好的坚固性)
使用ISO 11114-4中测试方法选择抗氢脆的金属材料
听说镍基合金高温下对氢脆敏感 是真的吗
可能有点挖坟了...
Wikipedia上是这样说的:
Material susceptibility 材料敏感性
Hydrogen embrittles a variety of metals including steel,[19][20] aluminium (at high temperatures only[21]), and titanium.[22] Austempered iron is also susceptible, though austempered steel (and possibly other austempered metals) displays increased resistance to hydrogen embrittlement.[23] NASA has reviewed which metals are susceptible to embrittlement and which only prone to hot hydrogen attack: nickel alloys, austenitic stainless steels, aluminium and alloys, copper (including alloys, e.g. beryllium copper).[2] Sandia has also produced a comprehensive guide.[24]
氢使各种金属脆化,包括钢、铝( [19] [20] 仅在 [21] 高温下)和钛。 [22] 等温淬火铁也容易受到影响,尽管等温淬火钢(可能还有其他等温淬火金属)表现出更强的抗氢脆性。 [23] 美国宇航局已经审查了哪些金属容易脆化,哪些金属只容易受到热氢的侵蚀:镍合金、奥氏体不锈钢、铝和合金、铜(包括合金,例如铍铜)。 [2] 桑迪亚实验室还制作了一份全面的指南。 [24]
Steels 钢
Steels were embrittled with hydrogen through cathodic charging. Heat treatment (baking) was used to reduce hydrogen content. Lower bake times resulted in quicker fracture times due to higher hydrogen content.[25]
钢通过阴极充电变得氢脆化。采用热处理(烘烤)来降低氢含量。由于氢含量较高,烘烤时间越短,断裂时间就越短。 [25]
Steel with an ultimate tensile strength of less than 1000 MPa (~145,000 psi) or hardness of less than HRC 32 on the Hardness Rockwell Scale is not generally considered susceptible to hydrogen embrittlement. As an example of severe hydrogen embrittlement, the elongation at failure of 17-4PH precipitation hardened stainless steel was measured to drop from 17% to only 1.7% when smooth specimens were exposed to high-pressure hydrogen[2]
极限抗拉强度小于 1000 MPa (~145,000 psi) 或硬度洛氏硬度低于 HRC 32 的钢通常被认为不易发生氢脆。作为严重氢脆的一个例子,当光滑的试样暴露于高压氢 [2] 气时,17-4PH沉淀硬化不锈钢的破坏伸长率从17%下降到仅1.7%
As the strength of steels increases, the fracture toughness decreases, so the likelihood that hydrogen embrittlement will lead to fracture increases. In high-strength steels, anything above a hardness of HRC 32 may be susceptible to early hydrogen cracking after plating processes that introduce hydrogen. They may also experience long-term failures anytime from weeks to decades after being placed in service due to accumulation of hydrogen over time from cathodic protection and other sources. Numerous failures have been reported in the hardness range from HRC 32-36 and more above; therefore, parts in this range should be checked during quality control to ensure they are not susceptible.
随着钢强度的增加,断裂韧性降低,因此氢脆导致断裂的可能性增加。在高强度钢中,任何硬度高于HRC 32的钢都可能在引入氢气的电镀工艺后容易发生早期氢裂纹。由于阴极保护和其他来源的氢气随着时间的推移而积累,它们也可能在投入使用后数周至数十年的任何时间出现长期故障。据报道,在HRC 32-36及以上的硬度范围内发生了许多故障;因此,在质量控制过程中应检查此范围内的零件,以确保它们不易受到影响。
Testing the fracture toughness of hydrogen-charged, embrittled specimens is complicated by the need to keep charged specimens very cold, in liquid nitrogen, to prevent the hydrogen diffusing away.[26]
测试带氢、脆化试样的断裂韧性很复杂,因为需要在液氮中保持带电试样非常低温,以防止氢扩散。 [26]
Copper 铜
Copper alloys which contain oxygen can be embrittled if exposed to hot hydrogen. The hydrogen diffuses through the copper and reacts with inclusions of Cu
2O, forming 2 metallic Cu atoms and H2O (water), which then forms pressurized bubbles at the grain boundaries. This process can cause the grains to literally be forced away from each other, and is known as steam embrittlement (because steam is directly produced inside the copper crystal lattice, not because exposure of copper to external steam causes the problem).
含有氧气的铜合金如果暴露在热氢中会脆化。氢气通过铜扩散并与夹杂物反应 Cu
2O ,形成 2 个金属铜原子和 H2O (水),然后在晶界处形成加压气泡。这个过程会导致晶粒从字面上被迫彼此远离,被称为蒸汽脆化(因为蒸汽是在铜晶格内部直接产生的,而不是因为铜暴露在外部蒸汽中会导致问题)。
Vanadium, nickel, and titanium
钒、镍和钛[edit]
Alloys of vanadium, nickel, and titanium have a high hydrogen solubility, and can therefore absorb significant amounts of hydrogen. This can lead to hydride formation, resulting in irregular volume expansion and reduced ductility (because metallic hydrides are fragile ceramic materials). This is a particular issue when looking for non-palladium-based alloys for use in hydrogen separation membranes.[18]
钒、镍和钛合金具有很高的氢溶解度,因此可以吸收大量的氢。这可能导致氢化物的形成,导致不规则的体积膨胀和延展性降低(因为金属氢化物是易碎的陶瓷材料)。在寻找用于氢分离膜的非钯基合金时,这是一个特殊的问题。 [18]
Prevention 预防
Hydrogen embrittlement can be prevented through several methods, all of which are centered on minimizing contact between the metal and hydrogen, particularly during fabrication and the electrolysis of water. Embrittling procedures such as acid pickling should be avoided, as should increased contact with elements such as sulfur and phosphate.
可以通过多种方法防止氢脆,所有这些方法都以尽量减少金属和氢之间的接触为中心,特别是在制造和电解水过程中。应避免酸洗等脆化程序,也应避免增加与硫和磷酸盐等元素的接触。
If the metal has not yet started to crack, hydrogen embrittlement can be reversed by removing the hydrogen source and causing the hydrogen within the metal to diffuse out through heat treatment. This de-embrittlement process, known as low hydrogen annealing or "baking", is used to overcome the weaknesses of methods such as electroplating which introduce hydrogen to the metal, but is not always entirely effective because a sufficient time and temperature must be reached.[33] Tests such as ASTM F1624 can be used to rapidly identify the minimum baking time (by testing using design of experiments, a relatively low number of samples can be used to pinpoint this value). Then the same test can be used as a quality control check to evaluate if baking was sufficient on a per-batch basis.
如果金属尚未开始开裂,可以通过去除氢源并使金属内的氢通过热处理扩散出来来逆转氢脆。这种去脆化工艺,称为低氢退火或“烘烤”,用于克服电镀等方法的弱点,这些方法将氢引入金属,但并不总是完全有效,因为必须达到足够的时间和温度。 [33] ASTM F1624 等测试可用于快速确定最短烘烤时间(通过使用实验设计进行测试,可以使用相对较少的样品数量来确定该值)。然后,可以使用相同的测试作为质量控制检查,以评估每批烘焙是否足够。
In the case of welding, often pre-heating and post-heating the metal is applied to allow the hydrogen to diffuse out before it can cause any damage. This is specifically done with high-strength steels and low alloy steels such as the chromium/molybdenum/vanadium alloys. Due to the time needed to re-combine hydrogen atoms into the hydrogen molecules, hydrogen cracking due to welding can occur over 24 hours after the welding operation is completed.
在焊接的情况下,通常会对金属进行预热和后加热,以使氢气在造成任何损坏之前扩散出去。这是专门用高强度钢和低合金钢(如铬/钼/钒合金)完成的。由于将氢原子重新结合到氢分子中需要时间,因此在焊接操作完成后 24 小时内可能会发生焊接引起的氢裂纹。
Another way of preventing this problem is through materials selection. This will build an inherent resistance to this process and reduce the need of post processing or constant monitoring for failure. Certain metals or alloys are highly susceptible to this issue, so choosing a material that is minimally affected while retaining the desired properties would also provide an optimal solution. Much research has been done to catalog the compatibility of certain metals with hydrogen. [24] Tests such as ASTM F1624 can also be used to rank alloys and coatings during materials selection to ensure (for instance) that the threshold of cracking is below the threshold for hydrogen-assisted stress corrosion cracking. Similar tests can also be used during quality control to more effectively qualify materials being produced in a rapid and comparable manner.
防止此问题的另一种方法是通过材料选择。这将对这一过程产生固有的阻力,并减少后处理或持续监控故障的需要。某些金属或合金极易受到此问题的影响,因此选择一种受影响最小的材料,同时保留所需性能也将提供最佳解决方案。已经进行了大量研究来对某些金属与氢的相容性进行分类。 [24] ASTM F1624 等测试也可用于在材料选择过程中对合金和涂层进行排名,以确保(例如)开裂阈值低于氢辅助应力腐蚀开裂的阈值。在质量控制过程中也可以使用类似的测试,以更有效地鉴定以快速和可比的方式生产的材料。
Surface Coatings 表面涂层
Coatings act as a barrier between the metal substrate and the surrounding environment, hindering the ingress of hydrogen atoms. These coatings can be applied through various techniques such as electroplating, chemical conversion coatings, or organic coatings. The choice of coating depends on factors such as the type of metal, the operating environment, and the specific requirements of the application.
涂层充当金属基材与周围环境之间的屏障,阻止氢原子进入。这些涂层可以通过各种技术应用,例如电镀、化学转化涂层或有机涂层。涂层的选择取决于金属类型、操作环境和应用的具体要求等因素。
Electroplating is a commonly used method to deposit a protective layer onto the metal surface. This process involves immersing the metal substrate into an electrolyte solution containing metal ions. By applying an electric current, the metal ions are reduced and form a metallic coating on the substrate. Electroplating can provide an excellent protective layer that enhances corrosion resistance and reduces the susceptibility to hydrogen embrittlement.
电镀是在金属表面沉积保护层的常用方法。该过程涉及将金属基板浸入含有金属离子的电解质溶液中。通过施加电流,金属离子被还原并在基材上形成金属涂层。电镀可以提供优良的保护层,增强耐腐蚀性并降低对氢脆的敏感性。
Chemical conversion coatings are another effective method for surface protection. These coatings are typically formed through chemical reactions between the metal substrate and a chemical solution. The conversion coating chemically reacts with the metal surface, resulting in a thin, tightly adhering protective layer. Examples of conversion coatings include chromate, phosphate, and oxide coatings. These coatings not only provide a barrier against hydrogen diffusion but also enhance the corrosion resistance of the metal.
化学转化涂层是另一种有效的表面保护方法。这些涂层通常是通过金属基材和化学溶液之间的化学反应形成的。转化涂层与金属表面发生化学反应,形成一层薄而紧密的保护层。转化涂层的示例包括铬酸盐、磷酸盐和氧化物涂层。这些涂层不仅提供了防止氢扩散的屏障,而且还增强了金属的耐腐蚀性。
Organic coatings, such as paints or polymer coatings, offer additional protection against hydrogen embrittlement. These coatings form a physical barrier between the metal surface and the environment. They provide excellent adhesion, flexibility, and resistance to environmental factors. Organic coatings can be applied through various methods, including spray coating, dip coating, or powder coating. They can be formulated with additives to further enhance their resistance to hydrogen ingress.
有机涂层,如油漆或聚合物涂层,提供额外的保护,防止氢脆。这些涂层在金属表面和环境之间形成物理屏障。它们具有出色的附着力、柔韧性和耐环境因素。有机涂料可以通过多种方法应用,包括喷涂、浸涂或粉末涂料。它们可以用添加剂配制,以进一步增强其对氢气侵入的抵抗力。
Thermally sprayed coatings offer several advantages in the context of hydrogen embrittlement prevention. The coating materials used in this process are often composed of materials with excellent resistance to hydrogen diffusion, such as ceramics or cermet alloys. These materials have a low permeability to hydrogen, creating a robust barrier against hydrogen ingress into the metal substrate.[34]
热喷涂涂层在防止氢脆方面具有多种优势。该工艺中使用的涂层材料通常由具有优异抗氢扩散性的材料组成,例如陶瓷或金属陶瓷合金。这些材料对氢的渗透性较低,可形成坚固的屏障,防止氢气进入金属基材。 [34]
附一个可能有用的文档, NASA对氢脆的调查,英文的: Hydrogen Embrittlement - NASA Technical Reports Server (NTRS), 还有SANDIA实验室的报告
引用阿卡林Akkariin发表于7楼的内容听说镍基合金高温下对氢脆敏感 是真的吗
NASA只有24摄氏度的数据, 但是是高压环境(13MPa-68MPa). 310, 316不锈钢还行, 304不行, 镍基都不推荐, 铜镍没看到有测试, 铜合金表现都不错,钛恐怕不行, 铁基表现比铜基差一小些.
报告中写的(机翻):
干燥的氢气环境对铝及其合金的影响可以忽略不计。氢气的主要问题主要来自铸造厂在熔融、铸造和凝固过程中暴露于湿气和形成充满气体的空隙。这些空隙是材料缺陷,会影响铸造和锻造产品的机械性能,例如延展性和断裂韧性。在熔体冷却过程中,氢气扩散到铸件缺陷中并沉淀,在较低温度下氢气在固体金属中的溶解度降低而产生裂纹。在接近室温、压力高达 10 ksi (69 MPa) 的干燥氢气不会在铝合金中引起显着的氢脆效应。然而,当高强度铝合金在水溶液中被氢气电化学充电时,其延展性降低。铝合金在水性介质中脆化的主要机理可能是SCC,而不是纯HE效应。阳极材料溶解SCC或阴极氢脆的综合机理对于铝合金在水环境中仍然是一个悬而未决的问题。
铜和富铜合金通常不易发生氢脆,除非它们含有氧气或氧化铜。当含氧铜及铜合金在氢气环境中退火或加热时,氢原子扩散到金属中,与氧化铜或氧气反应生成水,如果温度高于375°C(705°F),则转化为高压蒸汽。这是HRE的一个典型例子,因为蒸汽会以裂缝和水泡的形式引起氢损伤,即使不施加外部压力,也会降低金属的断裂韧性和延展性。坚韧的沥青铜通常含有少量的CuO;因此,如果它们随后暴露在 370 °C (700 °F) 以上的温度下,则不应在任何温度下暴露于氢气中。与氧化亚铜颗粒反应的方程式为(式5):
镍和镍基合金具有良好的高温强度、氧化和耐热腐蚀性能。然而,对干氧化和化学腐蚀环境具有良好额定值的镍基合金并不意味着它也对HE免疫。作为一种元素,纯镍被氢严重脆化;因此,在富镍区域,大多数富镍成分的二元合金,如镍铜、镍铁、镍钴和镍钨,也被发现被氢高度脆化[40]。在一些富镍合金体系中,也有同样的观察结果。例如,已知被称为K-Monel的富镍合金在高压下被氢脆化。然而,由于热处理和产品形态等因素,镍对钢和高温合金复杂成分的影响分析起来更为复杂。几种含镍材料和镍基高温合金的HEE指数测量分别见表3和表4。
一般来说,钛及其合金在水环境中通常具有优良的耐腐蚀性能。这种卓越的耐腐蚀性能是由于在氧化条件下在空气和水中自然形成的薄、稳定和坚韧的氧化钛 (TiO) 膜。然而,在外加电流的过度阴极充电下,已经观察到其中一些钛合金在水性介质中发生氢脆。在中低正极充电条件下,钛上自然形成的TiO膜似乎能有效抑制氢的吸收。然而,在高阴极充电电流密度下,这种保护膜会分解并成为钛合金的非保护性物质,并允许原子氢渗透到大部分材料中。在海水等近中性电解质中,当与钛在高于 80 °C (175 °F) 的温度下偶联时,与锌、铝和镁等金属的电偶联可以诱导氢吸收增强和氢化物形成。另一方面,在干氢气体环境中,随着温度和压力的升高,钛及其合金会容易吸收氢气。相对少量的氢化钛沉淀物对大多数应用无害,特别是在氢浓度为 40 至 80 ppm(百万分之一)的范围内。然而,当温度高于 250 °C (480 °F) 时,会迅速形成过量的氢化钛。这种类型的氢脆是 HRE 型;然而,在高温工艺中,如焊接或氢气存在下的热处理,它也被一些行业认为是IHE型。 对于形成不稳定氢化物的金属,IHE和HRE之间的区别并不总是得到很好的认可,因为它们紧密地位于重叠区域,如图1所示。
钢的HEE磁化率一般可分为四类:奥氏体、铁素体、马氏体和沉淀硬化。一般来说,相对于铁素体钢,大多数低强度奥氏体钢不太容易受到氢脆的影响。然而,众所周知,马氏体钢和沉淀硬化钢极易受到HEE和IHE效应的影响。奥氏体不锈钢和FeNi-Cr高温合金在成分与HEE效应方面有一些共性,第5.4节(合金成分)中对此进行了更详细的讨论。关于HRE效应,在某些高温和高压下,氢原子可以扩散到金属中,并与钢基合金中的某些类型的元素和化合物发生内部反应。最常见的反应是在氢和碳化铁之间形成甲烷气体 (CH)。由于CH不能从钢中扩散出来,因此会发生积聚,从而导致开裂和起泡,从而导致氢脆,而失去强度和延展性。
对于钢基合金,可以从纳尔逊曲线判断钢对HRE的敏感性,纳尔逊曲线表示各种钢对氢敏感的温度和压力区域。第 6.2 节进一步详细讨论了用于预防和控制氢脆的 Nelson 曲线。在许多碳钢和低合金钢中添加铬和钼可作为有益的合金元素,防止HRE(其作用也称为氢侵蚀现象)脱碳和开裂。
镍基高温合金具有最复杂的微观结构,可以是固溶或沉淀强化。镍基合金的HEE指数数据比任何其他类型的高温合金都多。铁基高温合金起源于奥氏体不锈钢,其发展原理是将(面心立方体(FCC)基体与固溶硬化和沉淀形成元素相结合。铁基高温合金的主要特征是奥氏体基体由镍和铁制成,其中至少含有 25% 的镍以稳定 FCC 相。因此,铁基高温合金也称为镍铁基高温合金。钴基高温合金的微观结构不如镍基合金复杂。大多数钴合金不形成伽马素强化相,它们依赖于固溶奥氏体基体FCC的结合,最重要的是形成硬质碳化物颗粒作为强化机制。这三种高温合金的产品形态通常分为铸造型和锻造型。高温合金热处理和产品形态的差异会对HE的程度产生影响,如第5.3节所示。一般来说,已经发现传统的锻造和粉末冶金 (PM) 加工高温合金比具有类似成分的铸造多晶高温合金受高压氢环境的影响略小。
时段 | 个数 |
---|---|
{{f.startingTime}}点 - {{f.endTime}}点 | {{f.fileCount}} |