Thermal modeling and validation via time-resolved temperature measurements for nanosecond laser irradiation of a powder bed of micro metal particles
Thermal modeling and validation via time-resolved temperature measurements for nanosecond laser irradiation of a powder bed of micro metal particles
复制标题
DOI：
10.1016/j.optlastec.2022.107981
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Hanyu Song;Mengchen Wu;Weidong Liu;Benxin Wu
中科院分区：
文献类型：
--
作者：
Hanyu Song;Mengchen Wu;Weidong Liu;Benxin Wu
连续波（CW）激光器通常用于选择性激光烧结或熔化;但是短脉冲激光器（例如，脉冲持续时间为纳秒级）具有自己的潜在优势，例如高分辨率和小的残余热效应。与连续激光相比，纳秒激光在烧结或熔化过程中涉及到更多的参数（如脉冲频率），激光参数与粉末床热响应之间的关系也更加复杂。为了帮助从根本上理解的关系，并指导有效的参数选择，这是非常可取的，以开发一个纳秒激光照射的金属粉末床的热模型，并直接验证该模型通过原位瞬态温度测量。然而，据作者所知，整合这种模型开发和验证的研究工作很少报道。本文建立了纳秒激光辐照金属微粒粉末床的热模型。模型预测的瞬态表面温度的粉末床的历史同意合理以及由快速高温测量系统测量。在所研究的条件下，模型模拟表明，高频纳秒激光脉冲可以诱导一个显着的热积累效应的金属粉末床，由于其较低的热导率比散装金属。在相同时均激光功率下，通过改变脉冲频率，纳秒激光可以诱导出不同的温度历史、熔池演化和寿命，这表明纳秒激光在激光烧结中具有良好的可调性和灵活性。由于复杂的参数-热响应关系，这也意味着参数选择的挑战，这意味着通过时间分辨温度测量验证的热模型的重要性。
Continuous-wave (CW) lasers are often used in selective laser sintering or melting; but short-pulsed lasers (e.g., with a pulse duration on the nanosecond scale) have their own potential advantages, such as high resolutions and small residual thermal effects. Compared with CW lasers, nanosecond lasers involve additional parameters (such as the pulse frequency) and more complicated relations between laser parameters and the powder bed thermal responses in laser sintering or melting. To help fundamentally understand the relations and guide efficient parameter selections, it is highly desirable to develop a thermal model for nanosecond laser irradiation of a metal powder bed and directly validate the model via in-situ transient temperature measurements. However, research work integrating such model development and validation has been rarely reported to the authors’ best knowledge. In this paper, a thermal model has been developed for nanosecond laser irradiation of a powder bed of micro metal particles. The model-predicted transient surface temperature history of the powder bed agrees reasonably well with that measured by a fast pyrometry system. Under the conditions studied, the model simulations show that high-frequency nanosecond laser pulses can induce a significant thermal accumulation effect in a metal powder bed due to its lower thermal conductivity than that for a bulk metal. With the same time-averaged laser power, by changing the pulse frequency, a nanosecond laser can induce very different temperature histories, melt pool evolutions and lifetimes, suggesting the laser has a potential advantage of good adjustability and flexibility in laser sintering. It also means a parameter-selection challenge due to the complicated parameter-thermal response relations, implying the importance of a thermal model validated by time-resolved temperature measurements.