Hastelloy C-4

1. Introduction to Hastelloy C-4 Materials

Hastelloy C-4 (N06455) is an austenitic low-carbon nickel-molybdenum-chromium alloy. Compared with early alloys of similar composition (Nicrofer6616hMo), it features low carbon, silicon, iron and tungsten content. This composition delivers excellent structural stability at 650-1040℃, superior intergranular corrosion resistance, and eliminates susceptibility to edge corrosion and weld heat-affected zone corrosion under proper processing conditions.

2. Chemical composition of Hastelloy C-4

3. Hastelloy C-4 physical properties

Minimum room temperature mechanical properties of the alloy:

4. Hastelloy C-4 material characteristics

• Excellent corrosion resistance to most corrosive media, especially reducing environments
• Outstanding local corrosion resistance in halide-containing environments
• Weldability: Hastelloy C-4 supports multiple welding processes including GTAW, plasma arc welding, SMAW, GMAW and FCAW; pulse arc welding is preferred

Before welding, materials shall be supplied in annealed condition with scale, oil and surface marks fully removed. Weld joint surfaces on both sides shall be polished to bright metallic finish. Low heat input is required, and interpass temperature shall not exceed 150℃.

Metallographic structure: Hastelloy C-4 features a face-centered cubic lattice structure; its chemical composition ensures stable metallographic structure and anti-sensitization performance.

5. Hastelloy C-4 corrosion resistance

Elevated molybdenum and chromium content enables Hastelloy C-4 to resist erosion from various chemical media, including reducing media such as phosphoric acid, hydrochloric acid, sulfuric acid, chlorine, organic and inorganic chloride-containing solutions. High nickel content effectively prevents chloride-induced stress corrosion cracking, even in hot chloride solutions.