Hemispherical shell for forming e.g. petanque boule, has cover forming outer layer made of metal and core made of another metal different from former metal, where former metal includes hardness higher than hardness of latter metal

摘要

The shell (40) has a cover (42) forming an outer layer made of metal, and a core (41) made of another metal different from the former metal. The former metal has high Rockwell hardness ranging between 38 and 52, and is a martensitic type carbonated, alloy or stainless steel. The latter metal is an austenitic/ferretic stainless steel, smooth steel or ferrous alloy, and has low Vickers hardness ranging between 130 and 250 after thermal treatment operations such as hardening. An independent claim is also included for a method for realizing a hemispherical shell.