1. What is the GH4133 Material Grade
GH4133 is a nickel-based precipitation-hardening superalloy developed primarily for high-temperature structural applications, classified under China's GB/T (Guobiao/Tuijian, National Recommendation Standard) system for superalloys. It is equivalent to the internationally recognized alloy Inconel® 718 (UNS N07718) in terms of core performance and application scenarios, though with minor compositional adjustments to suit domestic manufacturing standards.
Designed to operate reliably at temperatures up to 650–700°C (1202–1292°F), GH4133 balances high mechanical strength, excellent fatigue resistance, and good corrosion resistance-making it a staple material in industries where components face combined thermal stress and mechanical loads. Its grade classification reflects its specialized role: the "GH" prefix denotes "Gao Wen He Jin" (high-temperature alloy) in Chinese, while "4133" is a sequential designation identifying its specific composition and performance profile within the GH alloy family.
It is widely used in aerospace, energy, and industrial sectors, with typical applications including aircraft engine components (e.g., turbine disks, compressor blades), gas turbine parts, and high-pressure structural components in nuclear power or petrochemical equipment.
2. What is the chemical composition of GH4133?
GH4133's performance is directly tied to its precisely controlled chemical composition, which prioritizes nickel as the base element, reinforced with alloying elements for precipitation hardening, corrosion resistance, and grain stabilization. Below is its typical nominal composition (by weight percentage, wt%), in line with China's GB/T 14992 standard for high-temperature alloys:
| Element | Content Range (wt%) | Primary Function |
|---|---|---|
| Nickel (Ni) | 50.0–55.0 | Base metal; provides structural stability and compatibility with other alloying elements. |
| Chromium (Cr) | 17.0–21.0 | Enhances oxidation and corrosion resistance by forming a protective Cr₂O₃ oxide film. |
| Iron (Fe) | Balanced (≈15–20) | Reduces material cost while maintaining mechanical strength and processability. |
| Niobium (Nb) | 4.75–5.50 | Key precipitation-hardening element; forms γ'' phase (Ni₃Nb) to significantly improve strength at high temperatures. |
| Molybdenum (Mo) | 2.80–3.30 | Enhances high-temperature creep resistance and solid-solution strengthening. |
| Titanium (Ti) | 0.65–1.15 | Aids in precipitation hardening (with Nb) and improves fatigue resistance. |
| Aluminum (Al) | 0.20–0.80 | Promotes formation of fine γ' phase (Ni₃Al) for additional strength; controls grain growth. |
| Carbon (C) | ≤0.08 | Limits carbide precipitation (to avoid brittleness) while ensuring grain boundary strength. |
| Manganese (Mn) | ≤0.35 | Improves weldability and reduces hot cracking during processing. |
| Silicon (Si) | ≤0.35 | Aids in deoxidation during melting; controls oxide inclusions. |
| Phosphorus (P) | ≤0.015 | Strictly limited (impurity) to prevent grain boundary embrittlement. |
| Sulfur (S) | ≤0.015 | Strictly limited (impurity) to avoid reducing corrosion resistance and ductility. |
Minor variations in composition may exist between manufacturers, but all must comply with GB/T 14992 to qualify as GH4133.
3. What is the hardness of GH4133?
The hardness of GH4133 is highly dependent on its heat treatment state, as precipitation hardening (via γ'' and γ' phases) is the primary mechanism for adjusting its hardness and strength. Below are the typical hardness values for its two most common heat treatment conditions, measured using the Rockwell C (HRC) or Brinell (HBW) scales (per GB/T 230.1 and GB/T 231.1 standards):
Solution-Annealed State:
After solution annealing (typically heated to 950–1050°C, held, then water-quenched), GH4133 is in a soft, homogeneous solid-solution phase with minimal precipitated strengthening phases. Its hardness is relatively low:
Rockwell C (HRC): ≤32
Brinell (HBW, 3000 kgf load): ≤340
This state is primarily used for manufacturing processes (e.g., forging, machining, forming) where ductility and workability are prioritized.
Aged State (Service Condition):
After solution annealing followed by aging heat treatment (typically a two-step process: 720°C for 8 hours, furnace-cooled to 620°C, held for 8 hours, then air-cooled), large quantities of fine γ'' (Ni₃Nb) and γ' (Ni₃Al/Ti) phases precipitate, significantly increasing hardness and strength. This is the standard state for in-service components, with hardness values:
Rockwell C (HRC): 38–45
Brinell (HBW, 3000 kgf load): 380–460
