page_title: Brass
section_title: Season cracking
hierarchical_section_title: Brass / Season cracking
caption_attribution_description: own pic taken 1999
context_page_description: Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical and electrical properties. It is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure.
  Brass is similar to bronze, another alloy containing copper that uses tin in place of zinc; both bronze and brass may include small proportions of a range of other elements including arsenic, lead, phosphorus, aluminum, manganese, and silicon. The distinction between the two alloys is largely historical, and modern practice in museums and archaeology increasingly avoids both terms for historical objects in favor of the more general "copper alloy".
  Brass has long been a popular material for decoration for its bright gold-like appearance, e.g. for drawer pulls and doorknobs. It has also been widely used for all sorts of utensils due to many properties, such as low melting point, workability, durability, electrical and thermal conductivity.
context_section_description: Brass is susceptible to stress corrosion cracking, especially from ammonia or substances containing or releasing ammonia. The problem is sometimes known as season cracking after it was first discovered in brass cartridges used for rifle ammunition during the 1920s in the British Indian Army. The problem was caused by high residual stresses from cold forming of the cases during manufacture, together with chemical attack from traces of ammonia in the atmosphere. The cartridges were stored in stables and the ammonia concentration rose during the hot summer months, thus initiating brittle cracks. The problem was resolved by annealing the cases, and storing the cartridges elsewhere.
caption: Cracking in brass caused by ammonia attack
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