The working principle of diffusion welding machine mainly includes the following key steps and components:
Basic working principle: Diffusion welding machine works in vacuum or protective atmosphere environment, and uses high temperature and pressure to make the material realize atomic diffusion connection in solid state. The specific process is divided into three stages:
Surface contact stage: The workpiece to be welded is in close contact under the action of pressure and temperature, and the micro-convex part undergoes plastic deformation to increase the actual contact area. The vacuum environment removes oxide film and contaminants to ensure pure metal surface contact.
Interface diffusion stage: High temperature causes atoms to diffuse across the interface to form local metallurgical bonding. Pressure promotes close contact of the interface and reduces porosity.
Volume diffusion and grain boundary migration stage: Atoms further diffuse into the material, grain boundaries migrate and reorganize, the interface gradually disappears, and a uniform metallurgical connection is formed.
Key process parameters:
Temperature: Determines the atomic diffusion rate. Too high a temperature may lead to grain coarsening. The typical range is 0.5~0.8 times the melting point of the material.
Pressure: Promote close contact of the interface and reduce porosity. The typical range is 5~50MPa.
Time: Affects the diffusion depth. Too long may reduce efficiency. The typical range is 10 minutes to several hours.
Vacuum: Prevent oxidation and remove surface adsorbed gas. The typical vacuum is ≤10⁻³Pa.
Equipment composition and workflow:
Core components: Including vacuum system (mechanical pump + molecular pump group), heating system (resistance heating or induction heating), pressurization system (hydraulic or mechanical pressure head) and control system (PLC or computer control of temperature, pressure, vacuum degree synergy).
Typical workflow: Workpiece preparation (surface polishing, cleaning, assembly), furnace vacuuming, heating and pressurization, heat preservation and pressure maintenance, cooling and pressure relief.
Technical features:
Advantages: No need to melt the parent material, avoid thermal cracks, pores and other fusion welding defects, suitable for dissimilar materials connection. High-precision, high-strength joints, environmentally friendly, no welding smoke, no spatter, no need for filling materials.
Limitations: Long process cycle, not suitable for mass production; high cost.
