1.What are the characteristics of G3 Hastelloy?
Excels in resisting oxidizing and reducing acids, such as sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid.
Has strong resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC), even in chloride-containing media.
Performs well in high-temperature corrosive environments, including flue gas desulfurization (FGD) systems and chemical reaction vessels.
Core elements: Nickel (Ni, ~48-58%), Chromium (Cr, ~21-23%), Molybdenum (Mo, ~6-8%), Copper (Cu, ~1.5-2.5%).
Trace elements (e.g., titanium, iron) are added to improve weldability and reduce intergranular corrosion risks.
Can be easily processed by cold working (e.g., rolling, drawing) and hot working (e.g., forging, extrusion) without significant brittleness.
Weldability is superior to many other nickel-based alloys; post-weld heat treatment is not always required, reducing production complexity.
Maintains stable mechanical properties and corrosion resistance at temperatures ranging from -200°C to 650°C, suitable for both low-temperature and medium-high temperature applications.
2.What is the mechanical strength of G3 Hastelloy?
Strength Variation with Temperature: As temperature increases, tensile strength and yield strength gradually decrease, while elongation slightly increases. For example, at 500°C, the tensile strength is approximately 550-600 MPa, and the yield strength is about 250-280 MPa.
Effect of Cold Working: Cold working (e.g., 30% cold rolling) can significantly improve strength-tensile strength can reach 900-1000 MPa, and yield strength can exceed 700 MPa-though ductility will decrease accordingly.
3.What is the yield strength of G3 Hastelloy?
The minimum yield strength specified by standards (e.g., ASTM B622, ASME SB-622) is 310 MPa.
Typical actual test values range from 310 MPa to 350 MPa, ensuring sufficient load-bearing capacity for structural use.
Annealed State: The standard heat treatment is annealing at 1050-1150°C, followed by rapid cooling (water quenching). This state achieves the lowest yield strength but the highest ductility, suitable for subsequent forming processes.
Cold-Worked State: Cold working (e.g., cold rolling, cold drawing) increases yield strength significantly. For example:
20% cold working: Yield strength ≈ 550-600 MPa.
40% cold working: Yield strength ≈ 750-800 MPa.
As temperature rises, the yield strength of G3 Hastelloy decreases due to increased atomic mobility.
Typical values at common temperatures:
200°C: ≈ 280-320 MPa
400°C: ≈ 260-290 MPa
600°C: ≈ 230-260 MPa
