A study on the feasibility of laser annealing to relieve residual stresses in cold spray coatings

One of the challenges regarding the application of laser polishing in injection mold manufacturing is to eliminate the tensile residual stress on a polished cavity surface without the extra expenses of an annealing vacuum furnace. This study aims to develop a fast laser annealing method using a dual-beam laser system by which a mold cavity can be laser-polished and then laser-annealed. Fourteen mold steel specimens were laser-polished by a dual-beam laser, resulting in a roughness reduction from the initial state, Sa 1.11 μm, to Sa 0.16 μm, a smoother surface finish. A numerical simulation of laser annealing using the current CW laser was implemented to optimize the laser annealing parameters to guide the experiment of CW laser annealing. XRD measurement results showed that the tensile residual stress dropped from an initial 638 MPa to 10 MPa in an annealing cycle time of 40 min at 750 °C; therefore, fatigue cracks or stress corrosion cracks (SCC) on the mold cavity will no longer occur. Confocal microscopy, X-ray diffraction, and scanning electron microscopy were used to obtain the microstructure and phase composition of the microstructures, demonstrate that laser polishing and laser annealing by a dual-beam laser is a fast and effortless technique which can be effectively employed in injection mold manufacturing.

Section: Numerical Simulation Of Laser Annealingmentioning

confidence: 99%

Laser Polishing and Annealing Injection Mold Using Dual-Beam Laser System

Chen

Zhou

et al. 2022

“…It uses compressed gas (air, helium, nitrogen, etc.) as an accelerated gas stream to drive powder particles (particle size 1-50 µm) to collide with the substrate at low temperature (room temperature to 600 • C), supersonic speed (300-1200 m/s), and complete solid state so that the particles undergo strong plastic deformation and deposit to form a coating [9][10][11][12][13][14].…”

Section: Cold Spray Technology Featuresmentioning

confidence: 99%

Study on Corrosion Resistance and Wear Resistance of Zn–Al–Mg/ZnO Composite Coating Prepared by Cold Spraying

Wang

Xiong

et al. 2019

Two composite coatings, Zn65Al15Mg5ZnO15 and Zn45Al35Mg5ZnO15, were prepared by the cold spray technique and were found to be compact, with no pits or cracks, based on scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) investigations. The results of the neutral salt spray (NSS) and electrochemical tests showed that the two composite coatings possess a suitable corrosion performance. However, the Zn45Al35Mg5ZnO15 composite coatings were more corrosion resistant and allowed a better long-term stability. In addition, they were found to exhibit the best wear resistance and photocatalytic degradation efficiency.

“…It uses compressed gas (nitrogen, helium and air, and etc.) as an accelerated gas stream to drive powder particles (size of 1-50 µm) to collide with the substrate at a low temperature (room temperature to 600 • C) and a supersonic speed (300-1200 m/s) to complete solid state, so that the particles will undergo a strong plastic deformation and deposit to form a coating [10][11][12][13][14][15][16]. Compared with the traditional painting, thermal spraying and other processes of offshore equipment, the low-temperature characteristics of cold spraying has the following advantages: (1) The cold working environment has a low temperature, and it results in a fast deposition coating speed, so there is a wide range of substrate can be applied.…”

Section: Introductionmentioning

confidence: 99%

Anticorrosion Properties of Zn–Al Composite Coating Prepared by Cold Spraying

Wang

Xiong

et al. 2019

In order to slow down the corrosion and wear of offshore equipment, the Zn–Al composite coating was prepared on Q345 substrate by cold spray technique. The mass fraction of Zn and Al in the raw material was 2:3. The microstructure of the original coating was observed by scanning electron microscopy (SEM) and was characterized by energy dispersive spectrometer (EDS). From the composite alloy coating obtained by cold spraying, it was observed that the Zn and Al particles were uniformly distributed without oxidation product, and the powder particles were significantly plastically deformed. The microstructure of the composite coating is very dense and has strong adhesion to the substrate. Neutral salt spray test (NSS) and electrochemical accelerated corrosion test results showed that Zn–Al composite coating can effectively provide corrosion protection.