This book clarifies the influence of process parameters of laser additive alloy steel and cast iron on defect distribution and provides a reference for the formulation of process parameters of parts remanufacturing. This book realizes the control of the microstructure of alloy steel and cast iron through process parameters. The engineer can adjust the structure of the deposited layer according to the method provided in this book. Furthermore, this book provides non-destructive evaluation methods for defects and mechanical properties of as deposited alloy steel and cast iron. Engineers can carry out non-destructive testing of damaged parts according to the methods provided in this book.