Laser peening
Encyclopedia
Laser peening, or laser shock peening (LSP), is the process of hardening or peening
metal using a powerful laser
. Laser peening can impart a layer of residual compressive stress on a surface that is four times deeper than that attainable from conventional shot peening
treatments. A coating, usually black tape or paint, is applied to absorb the energy. Short energy pulses are then focused to explode the ablative coating, producing a shock wave The beam is then repositioned and the process is repeated, creating an array of slight indents of compression and depth with about 5-7% cold work. A translucent layer, usually consisting of water, is required over the coating and acts as a tamp, directing the shock wave into the treated material. This computer-controlled process is then repeated, often as many as three times, until the desired compression level is reached, producing a compressive layer as deep as 1-2mm average.
Laser peening is often used to improve the fatigue resistance of highly stressed critical turbine
engine
components, and the laser (or component) is typically manipulated by an industrial robot
.
Prototype laser peening machines were developed in the 1970s, but they and subsequent versions over the past two decades were not cost effective because the lasers lacked the high repetition rate required for treating parts rapidly.
Peening
Peening is the process of working a metal's surface to improve its material properties, usually by mechanical means such as hammer blows or by blasting with shot . Peening is normally a cold work process...
metal using a powerful laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
. Laser peening can impart a layer of residual compressive stress on a surface that is four times deeper than that attainable from conventional shot peening
Shot peening
Shot peening is a cold working process used to produce a compressive residual stress layer and modify mechanical properties of metals. It entails impacting a surface with shot with force sufficient to create plastic deformation...
treatments. A coating, usually black tape or paint, is applied to absorb the energy. Short energy pulses are then focused to explode the ablative coating, producing a shock wave The beam is then repositioned and the process is repeated, creating an array of slight indents of compression and depth with about 5-7% cold work. A translucent layer, usually consisting of water, is required over the coating and acts as a tamp, directing the shock wave into the treated material. This computer-controlled process is then repeated, often as many as three times, until the desired compression level is reached, producing a compressive layer as deep as 1-2mm average.
Laser peening is often used to improve the fatigue resistance of highly stressed critical turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
engine
Engine
An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...
components, and the laser (or component) is typically manipulated by an industrial robot
Industrial robot
An industrial robot is defined by ISO as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes...
.
Prototype laser peening machines were developed in the 1970s, but they and subsequent versions over the past two decades were not cost effective because the lasers lacked the high repetition rate required for treating parts rapidly.
See also
- Ultrasonic impact treatmentUltrasonic impact treatmentUltrasonic impact treatment is a method of metal improvement that utilizes ultrasonic energy. The physical characteristics: controlled residual compressive stress, grain refinement and grain size reduction...
- PeeningPeeningPeening is the process of working a metal's surface to improve its material properties, usually by mechanical means such as hammer blows or by blasting with shot . Peening is normally a cold work process...
- Shot peeningShot peeningShot peening is a cold working process used to produce a compressive residual stress layer and modify mechanical properties of metals. It entails impacting a surface with shot with force sufficient to create plastic deformation...
- Low plasticity burnishingLow plasticity burnishingLow plasticity burnishing is a method of metal improvement that provides deep, stable surface compressive residual stresses with little cold work for improved damage tolerance and metal fatigue life extension...