1.What is alloy B?
Definition of Alloy B: Alloy B is a general term for a type of nickel - molybdenum alloys. Its main characteristic is its strong resistance to reducing acid corrosion, and it can maintain good performance in environments such as hydrochloric acid and sulfuric acid. The typical representative is Hastelloy B alloy, which is widely used in the chemical industry and other fields.
2.What is the Hastelloy B3?
Hastelloy B3 is an austenitic Ni - Mo alloy with the ASME grade N10675. Its nominal composition is 65Ni - 29.5Mo - 2Fe - Cr. It has excellent resistance to hydrochloric acid corrosion at various concentrations and temperatures, and also has good resistance to corrosion in non - oxidizing environments such as sulfuric acid, acetic acid, formic acid, and phosphoric acid. It is a nickel - based high - temperature alloy composed of nickel, molybdenum, cobalt and other elements, and is a new material improved on the basis of Hastelloy B2. It improves the thermal stability and corrosion resistance of the material, and also improves the hot - forming and cold - forming properties.
3.What is equivalent to Hastelloy B3?
There are no completely identical materials, but some nickel - based alloys with similar properties, such as some special nickel - molybdenum alloys developed by other manufacturers, have similar chemical compositions and performance characteristics, and can be used in some cases instead, but they need to be selected according to specific application requirements.
4.What is the difference between Hastelloy B3 and B2?
Chemical composition: Hastelloy B2 has a basic composition of nickel (Ni), molybdenum (Mo) and a small amount of iron (Fe), with a molybdenum content of about 26% - 30% and an iron content of 2% - 6%. Hastelloy B3 significantly reduces the iron and carbon content (carbon content ≤ 0.01%), increases the molybdenum content (28% - 32%), and adds a small amount of chromium (Cr, about 1% - 3%) to enhance oxidation resistance.
Corrosion resistance: B2 performs well in medium - concentration hydrochloric acid (20% - 40%) and sulfuric acid, but its corrosion resistance will decrease significantly in high - temperature (over 100°C) or environments containing oxidizing impurities. And it is prone to heat - affected zone corrosion after welding. B3 has significantly improved in these aspects. For example, in a boiling 10% hydrochloric acid solution, the corrosion rate of B3 is about 1/3 of that of B2, and it has more stable corrosion resistance in mixed acids containing oxidizing ions.
Mechanical properties: The mechanical properties of the two alloys are similar. The tensile strength at room temperature is both over 700MPa, and the elongation is about 40% - 50%. But B3 has slightly higher high - temperature strength and can maintain better stability below 400°C.
Processing performance: The hot - working temperature range of B3 is wider (900°C - 1200°C), while that of B2 is narrower (1000°C - 1150°C). During cold working, both B2 and B3 need to pay attention to work hardening, but the work - hardening rate of B3 is slightly lower, which is more suitable for cold forming of complex - shaped parts. In addition, the machinability of B3 is slightly better than that of B2, and the tool life can be extended by about 15% - 20%.
Application scenarios: B2 is suitable for reducing environments at normal temperature or medium temperature (≤80°C), such as low - concentration hydrochloric acid storage tanks and acetic acid production equipment. B3 is widely used in strongly corrosive environments, such as evaporators of high - concentration hydrochloric acid (30% - 37%), heating pipes of sulfuric acid recovery systems, and sulfur - containing oil and gas production equipment.
