Friction hydro pillar processing

Friction hydro-pillar processing (FHPP) is a solid-state joining technology which can be used for filling of surface and sub-surface cracks in thick metals. For example, FHPP was attempted for the first time to repair cracks in space shuttle external components of high-strength aluminum alloys. FHPP is also considered in repairing surface cracks in steam turbine rotors of a high-strength, high-temperature-resistant steel (Ref). Alternative methods such as fusion welding processes for in-service repairing of cracks in components of these high-strength steels remained difficult because of their high hardenability and mandatory need of pre-heating and post-weld heat treatment. In contrast, initial FHPP trials could achieve joint strengths up to 90% of the base materials in high-strength steel components, especially those used for petrochemical and thermal power plants. In particular, pressurized pipes and vessels of AISI 4140 steel are widely used in the power generation, oil and gas, and petrochemical industries. Initial studies on FHPP of this alloy have showed promising results.

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