DEF-STAN is shorthand for Defence Standard, a series of material standards developed by the UK’s Ministry of Defence.
Defence Standard 02-835 covers the “Requirements for High Strength Copper Nickel Manganese Alloy Forgings, Forging Stock Rods and Sections”, which is the alloy better known as Hiduron 191. This alloy was developed by Langley Alloys and has been successfully used in many naval applications. NES835 is also used to signify the alloy and requirements references in DEF-STAN 02-835.
DOD-C-24676 is a similar specification to DEF-STAN 02-835, but produced and maintained for the US Navy, where DOD is the acronym for the Department of Defence. Once again, Hiduron 191 has been supplied over many years to large naval projects.
The merits of Hiduron 191 in such applications can be explained thus. In critical marine applications, for example, naval ships, the requirement for instant service following periods of inactivity favours the anti-fouling and corrosion resistance characteristics of a cupronickel; but conventional cupronickels have the disadvantage of inherently low strength. A combination of reasonable strength with good corrosion resistance and impingement resistance is achieved with nickel aluminium bronze alloys but the higher strength levels are only achieved at the expense of toughness with consequent limited resistance to shock.
Hiduron 191 was developed to provide both the corrosion resistance and anti-fouling characteristics of conventional cupronickels but with superior tensile and toughness properties compared to aluminium bronzes. Its resistance to marine corrosion is comparable with that of conventional cupronickels, the combination of tensile strength and toughness is far superior to that available with aluminium bronzes and its properties are largely independent of section size. In addition, Hiduron 191 has a relatively high modulus of elasticity of a cupronickel compared with most other bronzes.
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