Nondestructivetesting and quality control of metal hardened-depth is an important problem to be solved in machinery industry. It belongs to material property testing.
金属表面硬化层深度的检测及控制是目前机械工业部门急需解决的一个问题，它属于材料检测的范畴。
2
Nondestructivetesting of metal hardened depth is an important and difficult job, which belongs to material property testing.
金属表面硬化层深度的检测是一项非常重要而又困难的工作。
3
Barkhausen effect is produced by ferromagnetic material under varying magnetic field, it can be used as a new method for nondestructivetesting of residual stress.