Welding of Nickel-Base Corrosion-Resistant Alloys

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Welding of Nickel-Base Corrosion-Resistant Alloys
镍基耐腐蚀合金的焊接

Abstract:
摘要：
The nickel-chromium-molybdenum alloys (Hastelloy alloy C) proved to be extremely important in the chemical processing industry, because they provided corrosion resistance over a wide range of reducing and oxidizing environments.
研究证实Ni-Cr-Mo合金（哈氏合金C）是化学处理行业非常重要的材料，因为在大范围的氧化、还原环境下有极好的抗腐蚀作用。

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1.   Effect of weld metal segregation on corrosion resistance
抗腐蚀材料焊接偏析的影响。
2.   Propensity to form porosity
气孔形成倾向。
3.   Solidification hot-crack sensitivity
焊接热裂纹敏感性。

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The nickel-chromium-molybdenum alloys (Hastelloy alloy C) proved to be extremely important in the chemical processing industry, because they provided corrosion resistance over a wide range of reducing and oxidizing environments. However, grain precipitation of carbides in the as-welded condition required a postweld solution heat treatment to restore optimum corrosion resistance
因镍铬钼合金（哈氏合金C）在很大范围的氧化、还原环境下具有很强的抗腐蚀作用，所以在化学处理行业其具有极其重要的使用价值，不过焊后颗粒碳化物沉淀需经过焊后热处理以恢复其抗腐蚀性！

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An important factor in this new alloy was the development of a reliable quantitative method for determining susceptibility to intergranular attack in the original C-type alloy and the newer C-276 and C-4 alloys. The maximum carbon content of alloy C-276 is 0,01% C with typical production compositions of about 0,005% C. Unfortunately, the optimum corrosion resistance of alloy C-276 was founded to be hampered by the precipitation of an intermetallic compound rich in molybdenum and tungsten.
其中这种新合金的一个重要特征就是可以精确得定量检测原始c型合金与新c-276、c-4合金间的晶间腐蚀。典型产品c含量为0.005%max，而c-276合金为0.01%max。不过不幸的是c-276合金的富含钼、钨的金属间化合物对其抗腐蚀性有阻碍作用。

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Hastelloy alloy B-2 was originally developed to resist hydrochloric acid in all concentrations up to the boiling point and is used in many applications involving the production of this acid, as well as acetic acid and other chemicals. The alloy also resists sulfuric acid and pure phosphoric acid. Without chromium, however, this alloy is vulnerable to corrosion attack in reducing acids when oxidizing salts such as ferric or cupric chloride are present, even in the parts-per-million range.
哈氏合金B-2在沸点以下能够抵抗任何浓度的盐酸并可在包括盐酸、醋酸以及别的化学产品中使用，也可以抗硫酸及纯磷酸。然而如果没有铬，这种合金在氧化性盐存在的情况下，如三价铁及CuCl2，对还原性酸的抗腐蚀性很差，即使是百万分率范围内。

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The G family of alloys has excellent resistance to phosphoric acid and has been used in wet-process phosphoric acid evaporators, agitator shafts, pumps, and in the handling of superphosphoric acid.
G族合金对磷酸具有很强的抗性并以应用于湿法磷酸的蒸发器、搅拌机轴、泵，以及高磷酸的处理。

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A filler metal that matches the composition of the base material is usually recommended when welding the nickel-chromium-molybdenum CR alloys.
Other processes, such as plasma arc welding (PAW), resistance spot welding (RSW), laser-beam welding (LBW), electronbeam welding (EBW), and friction welding, can be used. The plasma arc cutting process is commonly used to cut alloy plate into desired shapes and to prepare weld angles. Oxyacetylene cutting is not recommended, nor is the use of oxyacetylene welding (OAW) and submerged arc welding (SAW). Oxyacetylene welding is not recommended because of the possibility of carbon pickup from the flame, whereas submerged arc welding is not recommended because of its high heat input, chromium loss across the arc, and silicon pickup from the welding flux.
在焊接哈氏合金时推荐填充金属的成分与母材相当，其他焊接工艺如等离子焊PSW，点焊RSW，激光焊LBW，电子束焊接EBW及摩擦焊均可。等离子切割常被用于合金钢板的焊接坡口以及各种设计形状的切割。不推荐使用氧炔焰切割、焊接（OAW）及埋弧焊。不推荐使用氧炔焰焊接（气焊）是因其容易碳化，而埋弧焊的高温容易导致铬、硅流失。

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Generally, welding heat input is controlled in the low-to-moderate range. Wide weave beads are not recommended. Stringer bead welding techniques, with some electrode manipulation, are preferred. The nickel-chromium-molybdenum alloy weld metal is not as fluid as carbon steel and does not flow out as readily to "wet" the sidewalls.
通常焊接热量输入应控制在低于平常范围。不推荐使用宽波形焊道，而优先使用带运条的线状焊道。哈氏合金焊材不如碳钢的流动性好不能迅速流出侧壁。

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Therefore, the welding arc and filler metal must be manipulated so as to place the molten metal where it is needed. In addition to sluggishness, the penetration pattern of this alloy type is less than that of a typical carbon or stainless steel weld, and incomplete fusion is more likely to occur. Therefore, care must be taken to ensure that the groove opening is wide enough to allow proper torch or electrode manipulation and proper placement of the weld bead.
因此，必须使焊弧与填充金属进入熔融金属等需要处。‘焊透性模型’试验显示哈氏合金模型的渗透性低于碳钢及不锈钢模型，而且也更容易出现未完全融合现象。所以必须严格保证开槽宽度满足焊枪或运条的要求，且焊接方位须利于焊珠滴落。

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Welding Metallurgy
焊接冶金学
The net effect is that during the welding of low carbon nickel-molybdenum and nickel-chromium-molybdenum CR alloys, Heat-Affected Zone (HAZ) grain boundary precipitation is still a potential reality, despite the relatively low carbon content of these alloys. The amount and severity of precipitation will depend on the cooling rate through the intermediate temperature range from 1000 to 600oC.
尽管镍钼、镍铬钼、铬钒等低碳合金钢相对碳含量很低，热影响区依然存在晶界析出。大量、严重的晶界析出需在1000-600度的中低温范围内及一定的冷却速率才能发生。

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Fusion zone welding metallurgy of the nickel-molybdenum and nickel-chromium-molybdenum alloy family is important, because base materials are usually welded with filler metals of matching composition and because these alloys can be welded autogeneously (no filler added), as in the case of welded tubular products.
熔合区焊接冶金镍钼和镍铬-钼合金家庭是重要的，因为相应的材料通常是焊接与钎料的组成和匹配，因为这些合金可焊接autogeneously （无填料补充）的情况一样，焊接管产品。
Three issues should be considered in terms of the fusion zone:
三个问题，应考虑到条款的融合区：

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Effect of weld metal segregation on corrosion resistance
Propensity to form porosity
Solidification hot-crack sensitivity
焊缝金属偏析对耐腐蚀性能的影响，
形成孔隙度倾向，
凝固热裂纹敏感性

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Segregation. Because of the segregation of solute elements upon solidification (principally molybdenum, which segregates to the cellular dendritic boundaries of the fusion zone), it is generally accepted that the corrosion resistance of the weld metal will be marginally less than that of the more homogeneous wrought base material. Differences in corrosion performance, however, depend heavily on the severity of the corrosion environment.
隔离。由于分流溶质元素后，凝固（主要是钼，隔离，以树突状细胞的界限融合区） ，这是普遍认同的耐蚀性的焊缝金属将轻微低于该更均匀，造成基地材料。分歧在腐蚀的性能，但是，在很大程度上取决于严重程度的腐蚀环境。

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Porosity. Recognizing that the solubility of gas is greater in the liquid state than in the solid state, the subject of weld porosity is relevant to fusion zone discussion. The three most logical origins of gas-generated porosity are carbon monoxide, hydrogen, and nitrogen. However, in welding the low-carbon nickel-molybdenum and nickel-chromium-molybdenum alloys, the cause of porosity is not believed to be from the formation of carbon monoxide. As long as there is a residual silicon or aluminum content in the weld deposit, the oxygen potential is too low for the formation of carbon monoxide.
孔隙度。认识到溶解度的气体是更大的，在液体状态，比在固体状态下，受焊缝孔隙率是相关的熔合区的讨论。三个最合乎逻辑的起源气体产生的孔隙度是一氧化碳，氢，氮。然而，在焊接低碳镍钼和镍铬-钼合金，事业的孔隙度是不相信是从形成一氧化碳。只要是有残余硅或铝含量在焊缝存款，氧势太低，形成一氧化碳。

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Gas hole formation can be caused by hydrogen evolution. As is well known, even the smallest amount of water will be reduced by metal deoxidizers, releasing a sufficient volume of gas to create porosity. Hydrocarbons can also dissociate and go into solution.
气孔的形成可以造成析氢。如所周知，即使是最小的耗水量将减少金属脱氧剂，释放出足够量的气体，创造孔隙度。碳氢化合物也可以分解和进入的解决办法。