ER4008 Aluminum TIG Welding Rod comes in a 10 lb box and is alloyed with copper to render superior tensile properties in heat-treated circumstances. Heat treatable rod has limited fluidity and poor resistance to hot cracking. Welding rod has silicon as a principle alloying element and meets AISi5 ISO designation. Rod is also susceptible to stress corrosion cracking in a fully hardened condition such as heat-treated circumstances.