38 THE NAVY OCEAN ENGINEERING PROGRAM 



technology has permitted the development of vehicles with useful pay- 

 load capability for only modest operating depths and limited maneuver- 

 ability. Extending our deep ocean capabihties will require advancement 

 in material technology far beyond that required for any other application, 

 including aerospace. 



A variety of materials are presently undergoing exploratory develop- 

 ment. Materials with high compressive-strength-to-density ratios are re- 

 quired to provide deep-submergence pressure hulls which will be buoyant 

 and resist the high compressive loads imposed by great depths. Materials 

 are being evaluated under environmental conditions simulating those to 

 which the material will be exposed in actual operation. In this context, 

 environmental conditions are taken to include not only the physical char- 

 acteristics of the medium in which the material functions, but also the 

 loads to which it may be exposed during its useful lifetime. 



The material requirements for "going deep" are numerous and include 

 the development of materials for pressure hulls, piping and machinery sys- 

 tems exposed to submergence pressures, and materials to augment deep- 

 submergence vehicle buoyancy. 



It is important to note that for most applications not only must the 

 structural material have a high strength-to- weight ratio, but also it must be 

 weldable, tough, corrosion resistant, have good endurance properties, and 

 be available in heavy sections at a reasonable price. 



High-Strength HY 130/150 Steel 



The Navy has sponsored the development of a 5% Ni-Cr-Mo-V steel with 

 a yield strength of 130,000 to 150,000 psi. This steel has been given ex- 

 tensive evaluation testing at Navy laboratories. 



The HY 130/150 is a quenched and tempered steel which has been 

 metallurgically customized to have an optimum combination of strength 

 and toughness for a given thickness. In comparison to the conventional 

 submarine hull steel, HY 80, HY 130/150 steel features slightly lower Cr, 

 higher Ni, and addition of V, lower carbon, and tempering at 1050° F 

 rather than at 1225° F. Welding development at the low end of the range 

 (130,000 psi) has been successful, and work is proceeding toward improve- 

 ing the weld filler metal to a point comparable with or higher than the base 

 metal (150,000 psi). 



HY 1 30/1 50 steel has been specified as the hull materials for the Navy's 

 Deep Submergence Rescue Vehicle (DSRV), which will be able to descend to 



