Abstract: The basic principle and method of testing steel and iron material quality by initial incremental permeability is stated. Using single chip computer to process the collected data according to mathematical statistics method such as regression analysis, qualitative and quantitative testing of mass fraction of carbon, hardness, carburized layer depth, cracks and friction welding defects of steel and iron parts are accomplished by "WGF-I type microcomputer-based automatic evaluator of material, quality for steel and iron". Its testing precision is±0.02 % for C, ±1HRC, ±10 HBS for hardness and±0.05mm for cazburized layer depth separately. Its testing speed is 1500 parts per hour.

Key words: Iron, Non-destructive testing, Steel