(GDS) Hardness & Microhardness Testers ICP Spectroscopy Mechanical Testing System Scanning Electron Microscopy (SEM) / Energy Dispersive Spectroscopy (EDS) Resources Alloying... of NHML. Customer problem: Turbine shaft fractured transversely during low temperature. What NHML did to solve problem: Recommended nickel bearing steel be used in lieu of 4340 low... alloy steel to improve toughness at low temperture. Also recommended that strut to shaft weldments be stress relieved after welding and subsequently shot peened to improve fatigue...