Case Study: Process developed for brazing white cast iron to low carbon steel
Not many heat treatment companies would be tasked with developing a process to attach white iron castings to plain carbon steel. The process also needed to harden the white iron to a Rockwell “C” hardness of 60 minimum while keeping the low carbon steel soft and weldable. The end use of this project was a component that could be welded to specific steel surfaces of mining equipment. The hardened white iron casting provides exceptional wear resistance and protects the mining equipment from unnecessary wear when used in an exceptionally abrasive environment. In use, the white iron component will eventually wear away. At that point, the steel surface of the mining equipment is ground smooth and a replacement wear product is welded in its place.
The process that was developed needed to create an extremely strong bond between the white iron and the low carbon steel. Vacuum brazing steel and white iron castings was the chosen process. The overall process development process included:
- Braze alloy selection
- Identifying and specifying surface conditions of both the white iron and low carbon steel braze surfaces
- Work procedure development including component assembly methods and cleaning
- Fixture design and development
- Load size and racking
- Furnace cycle development for the vacuum brazing steel process
- Furnace cycle development for the white iron hardening process
- Secondary operations following all the brazing and hardening processes
- Development of applicable component testing to confirm the integrity of the product
The end result of this process development is a component that met all of the design requirements. From a manufacturing standpoint, this process has produced virtually no in-house scrap, field failures or customer complaints.