... cylindrical 4.Test large, thick, heavy Other type of impact devices MaterialMethodImpact deviceD/DCD+15CGEDLSteel and cast steelHRC20~68.519.3 ... groove or reentrant surfaceC:Test small, light, thin parts and surface of hardened layerG:Test large, thick, heavy and rough ... surface steelE: Test super high hardness materialDL: Test slender narrow groove ...