Volume 51 Issue 5
Jun.  2022
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Xue Yafei, Luo Ziyi, Han Shanguo, Cai Detao, Xu Wanghui, Fang Weiping, Liu Haoting. Effect of laser scanning speed of the removal quality of rust layer on carbon steel surface[J]. Infrared and Laser Engineering, 2022, 51(5): 20210389. doi: 10.3788/IRLA20210389
Citation: Xue Yafei, Luo Ziyi, Han Shanguo, Cai Detao, Xu Wanghui, Fang Weiping, Liu Haoting. Effect of laser scanning speed of the removal quality of rust layer on carbon steel surface[J]. Infrared and Laser Engineering, 2022, 51(5): 20210389. doi: 10.3788/IRLA20210389

Effect of laser scanning speed of the removal quality of rust layer on carbon steel surface

doi: 10.3788/IRLA20210389
  • Received Date: 2021-06-11
  • Rev Recd Date: 2021-08-17
  • Publish Date: 2022-06-08
  • Laser cleaning of rust layer on the surface of carbon steel was studied by fiber laser, the effect of laser scanning speed on the removal quality of rust layer was studied by white light interferometer, optical microscope and Raman spectrometer. The results show that, when the laser scanning speed is less than 2 000 mm/s, the high spot overlap rate and strong heat accumulation effect, lead to the melting and recondensation of the substrate surface, and a secondary oxidation occurs on the sample surface, which result the formation of a complex iron oxide film, at the same time, the surface roughness of the sample is the smallest. When the laser scanning speed is increased to 3000 mm/s, the rust layer on the surface of the sample is completely removed, the color of the metal substrate is exposed, and the secondary oxidation on the surface of the substrate is weakened. When the scanning speed continues to increase, due to the low spot overlap rate, the laser energy absorbed by the rust layer is less, only part of the rust layer is removed, the residual rust layer begins to appear on the surface of the sample, and with the increase of scanning speed, the residual rust layer and surface roughness increase. Better rust removal effect can be obtained by adjusting the scanning speed, after optimization the process, when the laser power is 120 W, the rust removal efficiency reaches 1.5 m2/h.
  • [1] Sun S, Chen W, Yi S, Wang Junxiang, et al. Study of the corrosion protection behavior of neutral water-based rust remover on carbon steel [J]. Colloids & Surfaces A: Physicochemical & Engineering Aspects, 2018, 558: 130-137.
    [2] Li Jianfeng, Ge Shengsong, Wang Junxiang, et al. Water-based rust converter and its polymer composites for surface anticorrosion [J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018, 537: 334-342.
    [3] Tong Yanqun, Zhang Ang, Huang Jianyu, et al. Distribution and influence of oxygen content of laser pretreated aluminum alloy surface before welding [J]. Chinese Journal of Lasers, 2019, 46(2): 0202003. (in Chinese)
    [4] Xia Peiyun, Yin Yuhuan, Cai Aijun, et al. Laser cleaning process of 2219 aluminum alloy anodic oxide film before welding [J]. Chinese Journal of Lasers, 2019, 46(1): 0102005. (in Chinese)
    [5] Zhang Guangxing, Hua Xueming, Li Fang, et al. Research and application status of laser de-rusting and de-painting [J]. Hot Working Technology, 2019, 48(18): 1-4. (in Chinese)
    [6] Sanz M, Oujja M, Ascaso C, et al. Infrared and ultraviolet laser removal of crustose lichens on dolomite heritage stone [J]. Applied Surface Science, 2015, 346(15): 248-255.
    [7] Li Shuai, Li Ye, Li Pan, et al. Study on the varnish stripping experiment based on the high power fiber laser [J]. Infrared and Laser Engineering, 2017, 46(S1): S106008. (in Chinese) doi:  10.3788/IRLA201746.S106008
    [8] Pan Yu, Wang Mingdi, Liu Jincong, et al. Process and mechanism of HT200 laser de-rusting for 100 W fiber laser [J]. Applied Laser, 2019, 39(2): 269-274. (in Chinese)
    [9] Yang Mingkun, Zhou Fangrong, Ma Yi, et al. Laser rust removing process of deep rusting steel plate [J]. Applied Laser, 2018, 38(6): 975-980. (in Chinese)
    [10] Ren Zhiguo, Wu Changzhong, Chen Huaining, et al. Mechanism of laser derusting and surface properties of low carbon steel [J]. Opto-Electronic Engineering, 2017, 44(12): 1210-1216. (in Chinese)
    [11] Zhang Yan, Huang Yaping. Finite element simulation and parameter optimization of laser rust removal technology for marine steel plate [J]. Applied Laser, 2020, 40(2): 294-299. (in Chinese)
    [12] 佟艳群. 激光去除金属氧化物的机理与应用基础研究 [D]. 江苏大学, 2014.

    Tong Yanqun. Study on mechanism and application fundamentals of laser remobal of metal oxides [D]. Zhenjiang: Jiangsu University, 2014. (in Chinese)
    [13] Xue Yafei, Wang Wei, Wang Xuefeng, et al. Laser cleaning technology of 38CrMoAl material surface pollutants [J]. Infrared and Laser Engineering, 2018, 47(7): 0706004. (in Chinese) doi:  10.3788/IRLA201847.0706004
    [14] Zhou Jianzhong, Li Huating, Sun Qi, et al. Laser derusting mechanism of AH32 steel based on cleaned surface topography [J]. Optics and Precision Engineering, 2019, 27(8): 1754-1764. (in Chinese) doi:  10.3788/OPE.20192708.1754
    [15] de Faria D L A, Silva S V, Oliveira M T D. Raman microspectroscopy of some iron oxides and oxyhydroxides [J]. J Raman Spectrosc, 1997, 28(11): 873-878. doi:  10.1002/(SICI)1097-4555(199711)28:11<873::AID-JRS177>3.0.CO;2-B
    [16] Yang Xiaomei. The research of raman spectrum on steel rusty layer from atmosphere corrosion [J]. The Journal of Light Scattering, 2007, 19(2): 134-137. (in Chinese) doi:  10.3969/j.issn.1004-5929.2007.02.007
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Effect of laser scanning speed of the removal quality of rust layer on carbon steel surface

doi: 10.3788/IRLA20210389
  • 1. China-Ukraine Institute of Welding, Guangdong Academy of Sciences, China-Ukraine Belt and Road Joint Laboratory on Materials Joining and Advanced Manufacturing, Guangdong Provincial Key Laboratory of Advanced Welding Technology, Guangzhou 510650, China
  • 2. Beijing Engineering Research Center of Industrial Spectrum Imaging, School of Automation and Electrical Engineering, University of Science and Technology Beijing, Beijing 100083, China

Abstract: Laser cleaning of rust layer on the surface of carbon steel was studied by fiber laser, the effect of laser scanning speed on the removal quality of rust layer was studied by white light interferometer, optical microscope and Raman spectrometer. The results show that, when the laser scanning speed is less than 2 000 mm/s, the high spot overlap rate and strong heat accumulation effect, lead to the melting and recondensation of the substrate surface, and a secondary oxidation occurs on the sample surface, which result the formation of a complex iron oxide film, at the same time, the surface roughness of the sample is the smallest. When the laser scanning speed is increased to 3000 mm/s, the rust layer on the surface of the sample is completely removed, the color of the metal substrate is exposed, and the secondary oxidation on the surface of the substrate is weakened. When the scanning speed continues to increase, due to the low spot overlap rate, the laser energy absorbed by the rust layer is less, only part of the rust layer is removed, the residual rust layer begins to appear on the surface of the sample, and with the increase of scanning speed, the residual rust layer and surface roughness increase. Better rust removal effect can be obtained by adjusting the scanning speed, after optimization the process, when the laser power is 120 W, the rust removal efficiency reaches 1.5 m2/h.

  • 碳钢因其低廉的价格,优良的力学、焊接等性能,在建筑、车辆、船舶、机械制造等领域具有广泛的应用。然而,由于环境湿度、温度等因素的作用,碳钢表面极易氧化生锈,从而降低了零部件的力学性能以及使用寿命[1-2]。因此,使用过程中,必须去除碳钢表面锈蚀层,在延长钢结构使用寿命的同时,为后续加工制造工艺(如焊接、喷漆等)做准备[3-4]。传统的机械打磨、喷砂、酸洗等除锈方法存在能耗大、污染环境、损伤基材等不足之处,因此,亟需一种绿色环保、高效的除锈技术。

    激光清洗作为一种新兴的除锈技术,通过高峰值功率的连续或脉冲激光照射锈蚀部位,锈蚀层吸收激光能量后经过气化、熔化、热振动等一系列物理化学变化,最终使锈蚀层脱离碳钢基底[5]。激光清洗具有成本低、无接触、无污染、精确可控等优点,在航空航天、汽车船舶、文物保护、微电子等领域具有广阔的应用前景[6-7]

    激光除锈研究还主要集中在工艺参数优化及除锈机理等方面。潘煜等研究了脉冲激光参数对碳钢除锈效果的影响规律,除锈等级达到Sa2.5级,同时激光作用后,碳钢表面生成了硬化层[8]。杨明昆等研究表明,扫描间距和激光重复频率对除锈效果影响很大[9]。任志国等研究表明激光除锈未对金属基材力学性能、微观组织、硬度等产生显著影响,同时分析了激光除锈的机理[10]。张燕等基于有限元模型,对船用钢板激光除锈工艺进行了模拟,并对工艺参数进行了优化[11]。佟艳群等研究了金属氧化物的激光去除机理,发现激光除锈过程中,激光烧蚀的物理化学效应和弹性振动效应同时存在[12]。薛亚飞等开展了38CrMoAl材料的激光清洗研究,认为基材表面污染物去除机理主要为振动效应,清洗前后基材表面无损伤[13]。目前,激光扫描速度对锈蚀层去除后,碳钢板表面成分、粗糙度等影响规律的研究还较少。

    文中使用纳秒脉冲激光器开展了碳钢板表面激光除锈试验,研究了不同激光扫描速度对除锈后表面形貌、成分及粗糙度等的影响规律及机制,并优化了激光除锈工艺参数。

    • 选用锈蚀等级为B级的Q235碳钢板作为试验对象,将钢板切割成尺寸为100 mm×100 mm×6 mm的样件。为了消除样件表面初始锈蚀层对实验结果的干扰,样件表面打磨抛光后,被浸泡在质量分数为3.5%的NaCl溶液中100 h,随后测得样件表面锈蚀层的厚度约为80 μm,根据拉曼测试,激光除锈前,锈蚀层成分主要由Fe3O4γ-FeooH、α-Fe2O3等组成。文中采用的激光除锈设备主要由激光器、扩束准直系统、扫描振镜系统、聚焦场镜、二维位移台及计算机控制系统等组成,如图1所示。所用激光器为纳秒光纤激光器,激光器波长为1064 nm,最大平均功率为200 W,脉冲宽度为60 ns,脉冲重复频率范围为20~50 kHz,聚焦场镜的焦距为160 mm,聚焦后光斑直径约300 μm。

      Figure 1.  Structure diagram of laser derusting system

    • 在除锈过程中,激光器发出的脉冲激光束经扩束准直后进入扫描振镜系统,计算机系统通过控制激光的开启关闭以及扫描振镜镜片的摆动,使入射的点光斑经反射后转变为光斑快速扫描运动的线光斑,点光斑运动的速度为激光扫描速度,线光斑经场镜聚焦后照射到锈蚀层表面,同时通过XY二维位移台及计算机控制系统调控除锈区域的形状和大小,激光除锈光斑扫描运动过程如图2所示。

      Figure 2.  Schematic diagram of spot scanning trajectory in laser derusting process

      激光扫描速度直接影响到锈蚀层去除质量,其中激光扫描速度$ v $、脉冲频率 $ f $、光斑直径$ d $和光斑搭接率$ \eta $的关系为[14]

      式中:在脉冲频率 $ f $ 和光斑直径 $ d $ 不变的情况下,光斑搭接率与激光扫描速度成反比关系。激光除锈过程中线间距为图2中各行之间的距离,线间距不同,各行之间光斑搭接率不同,文中试验过程中,保持光斑在XY轴的搭接率一致,根据扫描线速度确定光斑搭接率以及线间距。

      文中主要开展激光扫描速度对除锈效果的影响规律研究,在整个除锈过程中,计算机控制系统通过控制板卡和振镜控制卡来实现激光输出功率、频率、扫描速度、脉宽等参数的调控。此外,利用体视显微镜进行形貌分析,拉曼光谱仪分析试样表面成分,白光干涉仪测试样件面粗糙度SaSq

    • 在固定激光功率、脉冲宽度、脉冲重复频率分别为120 W、60 ns、20 kHz时,研究了激光扫描速度分别为1000、2 000、2500、3000、4000、5000 mm/s时,碳钢板表面锈蚀层去除质量。

      图3为激光除锈后碳钢板表面显微形貌图。从图可看出,当激光扫描速度小于2 000 mm/s时,试样表面出现基材熔化重凝现象,同时生成了蓝灰色氧化膜层,这是因为激光扫描速度小,光斑搭接率高,单位面积内激光作用时间长,热累积强,试样表面温度高,锈蚀层在被气化、熔化去除的同时,过高的温度导致碳钢基材出现熔化重凝现象,并二次氧化生成了大量蓝灰色氧化膜层。结合图4激光除锈后碳钢表面拉曼光谱可知,所生成的氧化膜主要由γ-FeooH、α-Fe2O3、Fe3O4γ-Fe2O3等组成 [15-16]。当激光扫描速度增加到3000 mm/s时,除锈后,基材表面呈现金属本身色泽,说明试样表面锈层去除干净,且基底表面无熔化重凝痕迹,此时,热累积作用不足以损伤基材,除锈效果最好。当激光扫描速度增加到4000 mm/s以上时,基材表面开始出现残留锈蚀层,激光扫描速度越大,残留锈蚀层越多。这是因为,当激光扫描速度过大时,单位面积内光斑的作用时间缩短,碳钢表面锈蚀层吸收的激光能量少,以至于仅有最外层部分锈蚀被去除,造成锈蚀层残留。

      Figure 3.  Micromorphology of carbon steel surface after derusting with different laser scanning speeds

      Figure 4.  Raman spectra of carbon steel surface after derusting with different laser scanning speeds

    • 图4为不同激光扫描速度除锈后碳钢表面拉曼光谱。当激光扫描速度小于2 000 mm/s时,结合图3图4可知,因光斑搭接率高,热累积效应强,锈蚀层去除后基底表面氧化生成了由γ-FeooH、α-Fe2O3、Fe3O4γ-Fe2O3组成的蓝灰色氧化膜。当激光扫描速度增加到2500 mm/s时,试样表面出现了碳钢基材和α-FeooH拉曼峰,蓝灰色氧化膜拉曼峰消失,这与图3中形貌测试结果一致。此时,弱的热累积效应导致碳钢基材表面氧化生成了α-FeooH膜。当扫描速度增加到3000 m/s时,碳钢基材拉曼峰强度最大,说明试样表面锈蚀层去除干净,但同时还存在氧化生成的α-FeooH膜。当激光扫描速度增加到4000 mm/s时,碳钢基底表面开始出现残留的锈蚀层Fe3O4γ-FeooH,碳钢基材拉曼峰强度开始降低。激光扫描速度继续增加时,残留锈蚀层增加,基底拉曼峰强度进一步下降,这与图3中激光除锈后显微形貌的测试结果是一致的。

    • 采用白光干涉仪研究了激光扫描速度对除锈后碳钢表面粗糙度的影响规律。如图5所示,随着激光扫描速度的增加,试样表面粗糙度增大。结合图3可知,当激光扫描速度小于2500 mm/s时,因试样表面发生了熔化重凝,熔融金属的流动填充了试样表面的凹坑,一定程度上类似于激光抛光作用,因此试样表面粗糙度最小。当激光扫描速度增加到3000 mm/s时,由图3图4可知,试样表面锈蚀层去除干净,且基材表面未发生熔化重凝现象,激光抛光作用减弱,因此,表面粗糙度显著增加。当激光扫描速度增加到4000 mm/s以上时,除锈后,出现残留锈蚀层,经测试除锈前锈蚀层的粗糙度SaSq分别为4.39、5.76 μm,其远大于碳钢基材表面粗糙度,这导致试样表面粗糙度进一步增加。

      Figure 5.  Surface roughness of carbon steel after derusting with different laser scanning speeds

      激光器输出功率和激光扫描速度在一定程度上决定了激光除锈效率,当扫描速度为3000 mm/s,激光功率为120 W时,锈蚀层去除干净,脉冲激光除锈效率达到1.5 m2/h,除锈效率采用锈蚀层去除面积和锈蚀层去除时间之比计算得到。

    • 文中利用纳秒激光对碳钢表面锈蚀层进行了去除试验,研究了激光扫描速度对除锈效果的影响规律,分析了除锈后试样表面显微形貌、表面成分及粗糙度,得到以下结论:

      (1)在激光功率为120 W、脉宽为60 ns、频率为20 kHz、扫描速度为3000 mm/s时,碳钢板表面除锈效果最好,碳钢基材无损伤,除锈效率达到1.5 m2/h。

      (2)当激光扫描速度过小时,因热累积效应,碳钢表面存在熔化重凝,同时二次氧化生成了由γ-FeooH、α-Fe2O3、Fe3O4γ-Fe2O3等组成的混合膜。随着扫描速度的增加,二次氧化减弱,当扫描速度增加到4000 mm/s以上时,试样表面开始出现残留锈蚀层,扫描速度进一步增大,残留锈蚀层增多。

      (3)当激光扫描速度小于2 000 mm/s时,因碳钢基材表面熔化金属的流动填充效应,试样表面粗糙度最小,随着激光扫描速度的增加,碳钢表面粗糙度增加。

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