Explosive Metal Hardening

PA&E’s Bonded Metals Division, formally known as Northwest Technical Industries (NTI), employs an explosive shock hardening metal working technique to generate a work-hardened surface on a fabricated metal part similar to results achieved through peen hardening. During the hardening operation, explosive materials are applied directly to the metallic surface to be hardened and are detonated, driving the resultant forces into the metal surface. The operation, essentially cold, works the metal surface and hardening can be induced up to 1/4″ deep.

Explosive Shock Hardening Applications

The most common application of explosive shock hardening is to cast high-manganese steel rail frogs and switchings. Other mining and excavating applications have applied explosive shock hardening to Hadfield’s steel and modified Hadfield’s alloys. Limited research has implied that rhenium can also be hardened through explosive shock hardening.

  • Hardening effects deepen and increase through subsequent applications of the explosive-hardening process. This effect begins to taper off significantly after four applications of the process.
  • Hardness values in cast manganese steel components have shown hardness increases of 230 Bhn, and up to 1/4″ deep.
  • Metallurgical analysis of shock hardened Hadfield’s steel and high-manganese steel have shown a martensitic transformation in the hardened zone.
  • There are essentially no size or configuration limits to the application of explosive shock hardening.