Which Post-Processes Achieve Optimal Strength and Hardness in Corrax WAAM Parts?

Precipitation Hardening Heat Treatment

Corrax (CX) stainless steel achieves its exceptional strength and hardness through precise precipitation hardening heat treatment. After WAAM deposition, components undergo solution annealing at 1065-1120°C followed by rapid cooling to room temperature. This creates a supersaturated martensitic matrix. The critical aging treatment then occurs at 480-560°C for 2-6 hours, precipitating fine intermetallic Ni3Ti particles throughout the microstructure. This aging process transforms the relatively soft as-deposited material (typically 35-40 HRC) to its final hardened state reaching 48-52 HRC, while simultaneously developing tensile strengths exceeding 1500 MPa. The precise temperature and time parameters must be carefully controlled to maximize precipitation strengthening while maintaining adequate toughness.

Stress Relief and Microstructural Homogenization

Prior to aging, WAAM-produced Corrax components require intermediate stress relief to address the significant residual stresses from the deposition process. A stabilization treatment at 650-750°C helps relieve stresses while initiating microstructural homogenization. For complex geometries prone to distortion, this step is crucial for maintaining dimensional stability during the final aging process. The thermal cycles also help dissolve any undesirable secondary phases that may have formed during WAAM's rapid solidification, ensuring a consistent microstructure throughout the component before the critical aging treatment.

Hot Isostatic Pressing for Enhanced Properties

For maximum mechanical performance, Hot Isostatic Pressing (HIP) can be applied to Corrax WAAM parts before the final aging treatment. HIP at appropriate temperatures and pressures eliminates internal porosity and micro-voids inherent to the WAAM process, increasing density and improving fatigue strength. The combination of HIP followed by optimized aging produces a more homogeneous microstructure with uniform precipitation distribution, enhancing both strength and dimensional stability for precision components in aerospace and tooling applications.

Precision Machining and Surface Treatment

Following heat treatment, precision CNC machining achieves final dimensions while maintaining the hardened structure. Due to Corrax's high hardness after aging, machining requires specialized tooling and parameters. Final surface treatments like polishing or EDM may be applied for specific applications. The completed components undergo rigorous material testing and analysis to verify hardness distribution, mechanical properties, and microstructural integrity meet the stringent requirements for this high-performance maraging stainless steel.