Abstract: Causes for metal shedding as a defect occurring during medium frequency induction heating & neck spinning process of the Cr-Ni light gas cylinder are analyzed by means of metallographic microscope，scanning electron microscope and energy spectrum analysis etc.As a result，it is revealed that it is over burning of the tube that leads to metal shedding thereof.Since the manufacturer normally employs medium frequency induction heating and 3-shaft-linkage spinning processes for neck-spinning of the gas cylinder，over-high temperature，and over-high deformation velocity that gets mechanical energy transform into thermal energy so as to get the temperature of some areas of the work piece rising up above the liquid phase point，and thus eventually cause the deformation over-burning of the metal.