Hastelloy B3
Material grade: Hastelloy B3
US grade: UNS N10675
1. Overview of Hastelloy B3 (N10675):
Hastelloy B3 (N10675) is a nickel-based high-temperature alloy composed of elements such as nickel, molybdenum, and cobalt, with a nickel content of about 65%. Hastelloy B3 (N10675) nickel-based alloy material is an improved new material based on Hastelloy B2, which enhances the thermal stability of the material, thereby improving corrosion resistance, while also improving hot and cold forming properties. In recent years, it has been increasingly used in the production of chemical equipment.
2.Chemical composition of Hastelloy B3 (N10675): see Table 1-1.
 Table 1-1                                      

3. Main characteristics of Hastelloy B3 (N10675) and welding and processing:
1. Material analysis: The mechanical properties of Hastelloy B3 (N10675) alloy plate in the solution state: as the heating temperature increases, its tensile strength, yield strength, and elastic modulus decrease, while the elongation, thermal expansion coefficient, thermal conductivity, and specific heat slightly increase; as the cold deformation rate increases, its hardness, tensile strength, and yield strength increase, while the elongation decreases.
2. Forming and processing characteristics: Analysis shows that the forming and processing characteristics of Hastelloy B3 are mainly as follows:
(1) The elongation of Hastelloy B3 material is relatively high, creating favorable conditions for cold pressing.
(2) Hastelloy B3 material is harder than austenitic stainless steel, with a more pronounced tendency for work hardening, so greater pressure is required during cold forming, or step forming is needed.
(3) When the cold forming deformation rate of Hastelloy B3 material is less than 10%, it does not affect the corrosion resistance of the processed parts, but in welding processing, the presence of residual stress may cause thermal cracks in the weld. Therefore, for parts that require subsequent welding processing, it is still necessary to eliminate the influence of residual stress as much as possible.
(4) Severe deformation during cold forming will increase the yield strength ratio of Hastelloy B3 material and increase sensitivity to stress corrosion and cracking, often requiring intermediate and final heat treatment processes.
(5) Hastelloy B3 material is very sensitive to oxidizing media and sulfur, phosphorus, lead, and other low melting point metals at high temperatures.
(6) In the temperature range of 600 to 800°C, if the heating time is too long, the Hastelloy B3 alloy will produce brittle phases, leading to a decrease in elongation, and when external force or deformation is restricted in this temperature range, thermal cracks are likely to occur. Therefore, when using hot forming, the temperature must be controlled above 900°C.
(7) Before processing and pressing Hastelloy B3 material, the surface of the mold in contact with the workpiece should be cleaned; during cold processing, lubrication methods can be used, and immediate degreasing or alkaline cleaning is required after forming.
(8) After water cooling the processed parts, the surface oxide film is relatively thick and should be thoroughly pickled; if there is residual oxide film, it may cause cracks during the next pressing; if necessary, sandblasting treatment can be done before pickling.
3. Welding and forming:
(1) Before forming and processing, if the original blank needs to be spliced with a weld, it is best to choose the tungsten inert gas arc welding (GTAW) method to better protect the weld from oxidation. If manual arc welding is used, it is easy to cause oxidation of the intermediate weld, and even if each layer is ground and cleaned, it is difficult to ensure thorough cleaning, and any residual fine oxide layer may affect the forming and processing performance of the weld. Before welding the workpiece, it is necessary to remove the attachments and oxide layers from the groove and base material surface, as the presence of oxide films and impurities will affect the performance of the weld and heat-affected zone. It is best to use a small current for welding, avoid slow speeds, do not oscillate, control the interlayer temperature below 100°C, and use argon protection on both the front and back sides to avoid high-temperature oxidation and loss of alloy elements. The surface of the weld should be ground smooth before pressing to remove the thicker oxide layer on the weld surface and supplemented with pickling. Because the oxide layer on the weld of Hastelloy B3 material is very hard, it is difficult to remove directly by pickling, and during the pressing and forming process, fine cracks are likely to occur, affecting the performance of the weld.
(2) The advantages of hot forming are that it can be formed in one go, avoiding work hardening. If the forming temperature can be well controlled, heat treatment can also be avoided. However, during the hot forming process, the temperature changes greatly, and each area has different temperatures. The surface in direct contact with the mold may be much lower than the temperature inside the metal, making it difficult to measure and control. Once the local material enters a sensitive temperature zone during processing, defects such as micro-cracks may occur, which are difficult to eliminate in subsequent solution heat treatment. Learning from the experience of processing plants, the cold forming process was chosen. The pressing method prioritizes mold pressing, and if rotary pressing is necessary, cold rotary pressing or warm rotary pressing at temperatures not exceeding 400°C should be used.
(3) In the cold forming process, when the deformation rate is large, a step-by-step forming process should be adopted. Intermediate heat treatment is required for step-by-step forming, and solution heat treatment is preferred, with the temperature controlled above 1000°C. The solution heat treatment process should reach temperatures of 1060 to 1080°C. After the workpiece is finally pressed into shape, it should undergo another solution heat treatment to eliminate residual stress and avoid affecting subsequent welding quality.
4. Heat Treatment:
Hastelloy B3 (N10675) should always be kept clean and free of contamination before and during heat treatment, which is very important. During the heating process, the workpiece must not come into contact with sulfur, phosphorus, lead, and other low-melting-point metals, as this can damage the alloy's performance and make it brittle. An electric furnace is preferred for heating; if a gas or oil furnace is used, the lower the sulfur content in the fuel, the better. According to the material manufacturer's recommendations, the total sulfur content in natural gas and liquefied petroleum gas should not exceed 0.1% (V), and the sulfur content in city gas should not exceed 0.25g/m3. The sulfur content in fuel oil should be less than 0.5% (W) for better results.
The furnace gas must be clean and preferably slightly reducing, avoiding fluctuations between oxidizing and reducing conditions. The heating flame must not directly contact the workpiece. The workpiece must be supported before entering the furnace to avoid undesirable deformation at high temperatures. The workpiece should be heated as quickly as possible, and it can only be placed in the furnace after the furnace temperature reaches the heat treatment temperature. After leaving the furnace, it should be rapidly water-cooled using immersion or uniform spraying over the entire surface. It is strictly forbidden to use a water hose for pouring to prevent uneven cooling, which can lead to abnormal deformation or tearing.
5. Specifications and Supply Status of Hastelloy B3 (N10675):
1. Variety Classification: Hastelloy B3 seamless pipe, Hastelloy B3 steel plate, Hastelloy B3 round steel, Hastelloy B3 forgings, Hastelloy B3 flanges, Hastelloy B3 rings, Hastelloy B3 welded pipes, Hastelloy B3 steel strips, Hastelloy B3 wire materials, and matching welding materials.
2. Delivery Status: Seamless pipe: solution + acid pickling, length can be customized; plate: solution, acid washing, edge cutting; welded pipe: solution acid pickling + RT% flaw detection; forgings: annealed + turned; bars in forged and rolled state, surface polished or turned; strips delivered in cold-rolled, solution soft state, and descaled; wire materials delivered in solution acid-washed coil or straight bar form, in solution straight bar fine polished state.