Method for measuring ultrafast laser absorptivity of powder material

Abstract

The invention discloses a method for measuring the ultrafast laser absorptivity of a powder material and belongs to the field of ultrafast laser additive manufacturing. The invention provides a method for testing the specific heat capacity of the powder material along with the temperature change under ultrafast laser irradiation necessary for testing ultrafast laser absorptivity and a piecewise fitting method for the functional relationship between the temperature change rate and the temperature of the powder material under the action of the ultrafast laser for the first time, and achieve accurate measurement of absorptivity of the powder material under the action of ultrafast laser. The method is wide in application range and high in measurement precision, is suitable for actual measurement of the ultrafast laser absorptivity of various powder materials, fills the technical blank of the ultrafast laser absorptivity test of the powder materials, and provides precious basic data for engineering practice and scientific research.

Description

technical field [0001] The invention belongs to the technical field of ultrafast laser additive manufacturing, in particular to a method for measuring the ultrafast laser absorption rate of powder materials. Background technique [0002] At present, laser additive manufacturing generally faces problems such as molten pool instability, severe segregation, coarse grains, and low mechanical strength, which limit its wide application in industrial production, aerospace and other fields. This phenomenon is more pronounced in long-pulse-width lasers because the pulse width is greater than the electron-phonon coupling time and produces continuous thermal action. Compared with continuous laser and long pulse width laser, ultrafast laser has significant advantages in high precision, shape control and controllability in powder material additive manufacturing. Although ultrafast lasers have shown significant advantages and broad application prospects in the field of additive manufactu...

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Problems solved by technology

Chinese patent 202010107934.0 (disclosure date May 26, 2020) heats the material to a preset temperature by coil heating and then measures the laser absorptivity of the powder material at that temperature. However, this method ignores the effect of the laser and the thermal history of the material under coil heating. Different, the error of the test value is too large, which cannot provide reference for the test of ultrafast laser absorption rate

[0005] In order to solve the problems in the above-mentioned prior art, the present invention proposes the specific heat capacity test method of the powder material changing with temperature under ultrafast laser irradiation for the first time, and accurately obtains the specific heat capacity of powder material changing with temperature under ultrafast laser irradiation, and solves the problem of The problem of inaccurate test absorptivity caused by the large deviation between the specific heat capacity used in the test and the actual specific heat capacity is solved; according to the characteristics of the temperature change of the powder material in the ultrafast laser irradiation stage and the natural cooling stage, the functional relationship between the temperature change rate and temperature is proposed. The segmented fitting method avoids the error in the calculation of the absorption rate caused by the fitting deviation

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