Hastelloy B-3, NS 3203

00Mo30Ni65Fe2Cr2 (B-3 alloy) is a new generation Ni-Mo corrosion-resistant alloy introduced by Haynes Company in the mid-1990s, trying to solve the technical trouble caused by insufficient thermal stability of Hastelloy B-2 alloy. The basis of the development is the research results of the combined effects of Fe and Cr on the thermal stability and corrosion resistance of Ni-Mo alloy. The addition of the appropriate amount of Cr and Fe and the other main components are controlled by the B-2 alloy composition interval. The alloy 3 greatly improves the thermal stability of the Ni-Mo alloy, while retaining the corrosion resistance of the B-2 alloy, so that the cracking of the B-2 alloy and the cracking of the hot working process can be solved.

7.3.3. 1 Chemical composition and structural characteristics
The chemical composition of 00Mo30Ni65Fe2Cr2 (B-3 alloy) is shown in Table 7-6. Compared with the B-2 alloy, this alloy reduces the carbon to less than 0.01%, adds more than 1% Cr, controls Fe in the range of 1% to 3%, and increases the amount of Mo by 1%. These changes reduce the precipitation of carbide and the intermetallic phase, Ni4Mo, which greatly improves the thermal stability of the alloy while retaining the corrosion resistance of the B-2 alloy. The alloy consists of a supersaturated single-phase a structure at both high and low temperatures. The medium-temperature short-time aging (<lh) does not cause phase separation between Ni4Mo and Ni3Mo, the carbon content is very low, and the carbides are also extremely rare.
7.3.3.2 Mechanical properties
The room temperature mechanical properties of 00Mo30Ni65Fe2Cr2 (B-3) alloy containing Cr1.5 and Fe1. 5 are shown in Table 7-36. The transient mechanical properties at high temperature are shown in Table 7-37.

Table 7-36 Mechanical properties of 00Mo30Ni65Fe2Cr2(B-3) alloy at room temperature

Table 7-37 High-temperature transient mechanical properties of 00Mo30Ni65Fe2Cr2(B-3) sheet

7.3.3.3 Thermal stability
The aging thermal stability data for Hastelloy B-3 alloy is shown in Table 7-38, and the TTT (Temperature-Time-Transition) graph is shown in Figure 7-35. The elongation after 700T aging is shown in Figure 7-36. These data fully demonstrate that the thermal stability of 00MO30Ni65Fe2Cr2(B-3), which controls Fe and Cr content, is much better than that of B-2 alloy, achieving the intended purpose of developing this alloy, which not only facilitates the manufacture and processing of equipment or components. It also creates conditions for resistance to intergranular corrosion and stress corrosion resistance. The data of these results also indicate that temperature is the key to the decline of alloy plastic toughness in the range of aging temperature and aging time studied, further illustrating the harmfulness of Ni4Mo precipitation.

Table 7-38 Ageing Thermal Stability of 00Mo30Ni65Fe2Cr2(B-3) Alloy

7. 3. 3. 4 Corrosion resistance General corrosion
Compared with B-2 alloy, 00Mo30Ni65Fe2Cr2(B-3) alloy has higher Mo content, and the content of Fe and Cr is controlled within the range that does not adversely affect the alloy. Therefore, the overall corrosion resistance of B-3 alloy should be slightly better. For the B-2 alloy, some corrosion data are shown in Tables 7-39, 7-40, and 7-37. The results of corrosion resistance in some acid solutions compared to other materials are shown in Table 7-41.

Table 7-39 Corrosion resistance of 00Mo30Ni65Fe2Cr2 in some acids

Table 7-40 Average Corrosion Rate of Solution Annealed Hastelloy B-3 Alloy in HF Acid Solution

Table 7-41 Corrosion resistance of 00Mo30Ni65Fe2Cr2 in several boiling acids compared with other corrosion resistant materials

Under the condition of less than 50% cold deformation, although the strength of B-3 alloy increases, the plasticity decreases, but it does not affect the corrosion resistance of this alloy in boiling 20% HC1 acid (Table 7-42). The general corrosion resistance of B-3 alloy in reducing acid can be seen, and B-3 alloy has the best corrosion resistance.

Table 7-42 Corrosion Resistance of Cold Deformed 00Mo30Ni65Fe2Cr2 Alloy in Boiling 20% HC1 (4 x 24h Test)

B intergranular corrosion
hastelloy B-3 welded sample in 110 ° C, 20% ~ 30% H2S04 + ferrous sulfate (pH < 1) solution after 96 days of the test results indicate that the heat affected zone of 00Mo30Ni65Fe2Cr2 alloy does not see intergranular Corrosion, while B-2 alloy produces intergranular corrosion (Table 7-43).

Table 7-43 Corrosion resistance of 00Mo30Ni65Fe2Cr2(B-3) alloy welding specimen

C stress corrosion
After annealing and subsequent 700^x lh aging U-bend specimens in boiling 60% H2S04*, 24h test results according to ASTM GT-30 method showed that B-3 alloy did not produce stress corrosion, while B-2 alloy Intergranular stress corrosion cracking occurred after 3 hours of the test. The results of stress corrosion test in H2S04 and HC1 of medium and heavy plate and thin plate specimens (annealing +700 °C x lh aging) also show that the stress corrosion resistance of B-3 alloy is much better than that of B-2 alloy (Table 7). -44).

Table 7-44 SCC Performance of 00Mo30Ni65Fe2Cr2 Medium and Heavy Plates

7. 3.3.5 Thermal processing, cold forming, heat treatment and welding performance
(1) Thermal processing. The hot workability of 00Mo30Ni65Fe2Cr2 alloy is good. The suitable heating temperature is 1230T. After the processed alloy is fired to reach the overall temperature uniformity, the hot processing operation will not encounter difficulties. Because the carbon content of the alloy is very low, in order to obtain hot processing. After the fine grain structure, the lower final deformation temperature and the appropriate final deformation should be controlled. Since the alloy has better thermal stability than the B-2 alloy, it does not encounter the trouble of the B-2 alloy during the thermoforming process.
(2) Cold forming. Although this alloy is sensitive to cold work hardening, it has good cold workability and can be cold worked by a usual cold forming method.
(3) Heat treatment. The supply state of 00Mo30Ni65Fe2Cr2 alloy is solution annealing, and the product which can be rapidly cooled has an annealing temperature of 1065T and rapid quenching after heat preservation. The rolled sheet and wire have a bright annealing temperature of 1150T and a cooling method of hydrogen cooling.
(4) Welding. The 00Mo30Ni65Fe2Cr2 alloy has good weldability and can be welded by the general method of GTAW, GMAW and SMAW. In the welding process, excessive heat input should be prevented, and the interlayer temperature should be controlled below 93 °C. Oxyacetylene and submerged arc welding are not recommended.
The welded filler metal may be a solder material of the same composition as the base material. The mechanical properties of the weld metal after welding can meet the engineering needs (Table 7-45).

Table 7-45 Mechanical properties of weld metal after welding with the same composition as B-3 alloy

7. 3. 3. 6 Physical properties
The physical properties of  hastelloy B-3 alloy are shown in Table 7-46 and Table 7-47.

Table 7-46 Physical properties of hastelloy B-3 alloy

Table 7-47 Linear expansion coefficient of 00Mo30Ni65Fe2Cr2(B-3) alloy

7.3.3.7 Application
This alloy is used in the same field as the Hastelloy B-2 alloy. The thermal stability of the alloy is much better than that of the alloy B-2, so its resistance to intergranular corrosion and stress corrosion is better than B-2. For products with stricter requirements for welding and thermoforming, it is advisable to use 00Mo30Ni65Fe2Cr2 (B-3) alloy.