Equiaxed Crystal Casting Superalloy Components Welding Supplier

Welding Technology for Equiaxed Crystal Superalloy Castings

Welding equiaxed superalloy castings requires precise filler matching, temperature control, and shielding to ensure crack-free and mechanically stable joints.

• TIG welding with matched Inconel, Rene, or Hastelloy fillers

• Laser welding for narrow seam repair in thin-walled castings

• Controlled interpass temperatures and argon shielding to reduce oxidation

• Heat treatment and HIP for structure recovery

We maintain AS9100D and NADCAP standards in all welding procedures.

Common Alloys for Equiaxed Welded Components

These alloys require precise weld prep, interpass control, and post-weld treatments to retain service performance.

Case Study: Laser Seam Weld on Equiaxed Inconel 738 Stator Ring

Project Background

A gas turbine stator ring made from equiaxed Inconel 738 had surface defects and edge discontinuities after casting. Laser welding was used to restore the part, followed by heat treatment at 980°C and CMM inspection to verify contour accuracy.

Typical Welded Component Models and Applications

Each part was inspected and certified to meet fatigue, pressure, and thermal cycle requirements.

Welding Challenges in Equiaxed Cast Superalloy Components

1. Crack risk increases above 175°C interpass temperature in high gamma prime alloys like Inconel 738 and Rene 77.

2. Oxidation and porosity occur when O₂ levels exceed 100 ppm during TIG welds without adequate shielding.

3. HAZ hardness exceeds 420 HV in improper cooling conditions, reducing ductility in cast grain boundaries.

4. Thin sections distort >0.02 mm under laser welding without fixturing or preheat procedures.

5. Residual stress >250 MPa forms if post-weld heat treatment is not properly applied to equiaxed grain structures.

Welding Process Solutions

1. Argon shielding <50 ppm O₂ eliminates oxidation, ensuring weld bead integrity on trailing edges and cooling holes.

2. Preheat to 300°C and interpass <150°C limits cracking and thermal gradient effects in thick-cast equiaxed walls.

3. Matched ERNiCrMo filler wire provides chemical compatibility and thermal fatigue resistance up to 1050°C.

4. Post-weld heat treatment at 980°C normalizes hardness and relieves thermal stress in HAZ-affected zones.

5. HIP at 1030°C, 100 MPa for 4 hrs eliminates internal porosity, restoring fatigue performance of welded equiaxed castings.

Results and Verification

Welding Execution

All welding was performed using matched alloy filler with arc voltage stabilization. Weld beads measured 3 mm wide with depth of 1.5 mm, ensuring full penetration without distortion.

Post-Weld Processing

Components received heat treatment at 980°C for 2 hours. Where applicable, HIP at 1030°C, 100 MPa was applied to close porosity and restore ductility.

Inspection

X-ray NDT confirmed complete fusion. CMM measured profile tolerances to ±0.008 mm. SEM analysis verified microstructure continuity and weld interface integrity.

FAQs

1. What equiaxed cast alloys are commonly welded in turbine applications?

2. How do you prevent hot cracking during welding of equiaxed parts?

3. Can Rene or Inconel castings be welded without loss of grain integrity?

4. What post-weld inspections are performed?

5. Is HIP required after welding of equiaxed cast superalloy components?