DEF-STAN 02-835 is a UK Ministry of Defence material standard covering the "Requirements for High Strength Copper Nickel Manganese Alloy Forgings, Forging Stock Rods and Sections" - the alloy better known as Hiduron® 191. DEF-STAN is shorthand for Defence Standard.
NES835 is also used to signify the alloy and the requirements referenced in DEF-STAN 02-835. DOD-C-24676 is the equivalent specification maintained for the US Navy, where DOD is the US Department of Defense. Hiduron® 191, developed by Langley Alloys, has been supplied to large naval projects over many years.
Why use Hiduron® 191
Critical marine applications, such as naval ships, need instant service after periods of inactivity, which favours the anti-fouling and corrosion resistance of a cupronickel. Conventional cupronickels, however, have inherently low strength. Nickel aluminium bronze alloys achieve reasonable strength with good corrosion and impingement resistance, but their higher strength levels come at the expense of toughness, and therefore limited resistance to shock.
Hiduron® 191 was developed to provide the corrosion resistance and anti-fouling characteristics of conventional cupronickels, but with superior tensile and toughness properties compared with aluminium bronzes. Its marine corrosion resistance is comparable with conventional cupronickels, its combination of tensile strength and toughness is far superior to aluminium bronzes, and its properties are largely independent of section size. It also has the relatively high modulus of elasticity of a cupronickel, compared with most other bronzes.