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第16卷第5期精密成形工程2024年5月JOURNAL OF NETSHAPE FORMING ENGINEERING39激光功率和离焦量对2 000 MPa级热成形钢激光焊接接头组织与性能影响周婷婷1，刘岩2*，杜安娜1，张文广1（1.沈阳大学机械工程学院，沈阳 110044；2.沈阳大学辽宁省先进材料制备技术重点实验室，沈阳 110044）摘要：目的研究激光功率和离焦量对PHS2000型热成形钢激光焊接接头焊缝区及热影响区显微组织、拉伸特性和硬度分布的影响。
方法采用光学显微镜（OM）、扫描电子显微镜（SEM）分析焊接接头的显微结构；利用拉伸实验和显微硬度实验探究焊接接头力学性能的变化规律。
结果随着激光功率从3 500 W增至4 700 W，焊缝区与热影响区平均晶粒尺寸总体呈上升趋势，抗拉强度先上升后下降，焊缝区平均显微硬度值在635HV~651HV内浮动，热影响区平均显微硬度值在434HV~451HV内浮动；离焦量对焊缝区的组织分布有显著影响，不同离焦量下的组织分布均较为分散，热影响区的晶粒尺寸在离焦量为−3 mm时达到最大，为10.67 μm。
在不同激光功率和离焦量下，焊接接头的显微硬度值存在上下浮动，焊接接头各区的显微硬度分布规律基本一致，以焊缝为中心，两侧趋于对称分布。
硬度分布规律如下：焊缝区硬度>母材区硬度>热影响区硬度。
结论在本实验条件下，与离焦量相比，激光功率对焊接接头显微组织及拉伸强度的影响更大。
在焊接速度为150 mm/min条件下，设置激光功率为4 100 W、离焦量为−2 mm，此时抗拉强度最大，为1 715 MPa，达到母材抗拉强度的85%。
关键词：热成形钢；激光焊接；激光功率；离焦量；显微组织；力学性能DOI：10.3969/j.issn.1674-6457.2024.05.005中图分类号：TG456.7 文献标志码：A 文章编号：1674-6457(2024)05-0039-09Effect of Laser Power and Defocusing Amount on Microstructure and Properties of Laser Welding Joints in 2 000 MPa Grade Hot-formed SteelZHOU Tingting1, LIU Yan2*, DU Anna1, ZHANG Wenguang1(1. School of Mechanical Engineering, Shenyang University, Shenyang 110044, China; 2. Liaoning Provincial Key Laboratoryof Advanced Materials & Preparation Technology, Shenyang University, Shenyang 110044, China)ABSTRACT: The work aims to study the effect of laser power and defocusing amount on the microstructure, tensile properties and hardness distribution of the weld zone and the heat-affected zone of laser welding joints of PHS2000 hot-formed steel. Op-收稿日期：2024-03-12Received：2024-03-12基金项目：辽宁省自然科学基金（2023-MS-320）Fund：Natural Science Foundation of Liaoning Province(2023-MS-320)引文格式：周婷婷, 刘岩, 杜安娜, 等. 激光功率和离焦量对2 000 MPa级热成形钢激光焊接接头组织与性能影响[J]. 精密成形工程, 2024, 16(5): 39-47.ZHOU Tingting, LIU Yan, DU Anna, et al. Effect of Laser Power and Defocusing Amount on Microstructure and Properties of Laser Welding Joints in 2 000 MPa Grade Hot-formed Steel[J]. Journal of Netshape Forming Engineering, 2024, 16(5): 39-47.*通信作者（Corresponding author）40精密成形工程 2024年5月tical microscope (OM), scanning electron microscope (SEM) were adopted to analyze the microstructure of the welded joints;Tensile experiments and microhardness experiments were conducted to explore the change rule in mechanical properties of welded joints. With the increase of laser power from 3 500 W to 4 700 W, the average grain size of the weld zone and the heat-affected zone showed a general upward trend, the tensile strength firstly increased and then decreased, the average micro-hardness value of the weld zone fluctuated up and down from 635HV to 651HV, and the average microhardness value of the heat-affected zone fluctuated up and down from 434HV to 451HV; The defocusing amount had a significant effect on the tissue distribution of the weld zone, the tissue distribution in different defocusing amount were more dispersed. The grain size in the heat-affected zone grain size grew sharply due to the martensite grain. It reached a maximum of 10.67 μm in the defocusing amount of −3 mm. In different laser power and focusing amount, the microhardness value of welded joints fluctuated up and down. The distribution of microhardness of welded joints of all zones of the microhardness distribution was basically the same.In a pattern with the weld as the center, the two sides tended to symmetrical distribution. The rule of hardness distribution was weld zone>base material zone>heat affected zone. Under the experimental conditions, the laser power has a greater influence on the microstructure and tensile strength of the welded joints than the defocusing amount. Under the condition of maintaining welding speed of 150 mm/min, laser power of 4 100 W and defocusing amount of −2 mm, the maximum tensile strength is1 715 MPa, which reaches 85% of the tensile strength of the base material.KEY WORDS: hot formed steel; laser welding; laser power; defocusing amount; microstructure; mechanical properties随着社会对节能、减排、环保等理念重视程度的不断提高，汽车工业对安全性能和燃油经济的要求也不断提升，特别是在新能源汽车迅速崛起的背景下，轻量化已经成为降低能耗、提升车辆性能的重要手段[1-2]。
上海大学2009 ～2010 学年春季学期研究生课程论文课程名称：强光与等离子体物理课程编号：011102924论文题目: 在30飞秒的强激光脉冲作用下观察固态密度等离子体层的透明度作者姓名: 黄毅华学号: 09720103成绩:论文评语:评阅人:评阅日期:注:后附课程论文的正文在30飞秒的强激光脉冲作用下观察固体密度等离子体层的透明度摘要在没有预先形成等离子体的情况下，脉宽为30飞秒、强度为182μ厚的塑料薄片靶子。
这种量级的⨯的脉冲几乎可以完全透过0.1mW cm310/透过率远大于目前理论模型或数值模拟所预测的结果。
在背景强度为162W cm⨯时，相应的透过率将会减少40倍。
410/⨯，激光强度为172510/W cm这个结果需要一种新的电磁波在过密等离子体中传播的理论机理来解释。
关键词等离子体、强激光脉冲、透明Observation of Solid-Density Laminar PlasmaTransparency to Intense 30 Femtosecond LaserPulsesNear total transmission of 30 fs laser pulses through 0.1mμplastic foil targets has been observed for the first time at an intensity of 182⨯in absence ofW cm310/precursor plasma. This level of transmittivity is far above the level predicted by current theoretical models or numerical simulations. The transmittivity was found to drop by 40 times at an intensity of 172⨯and was within the experimental410/W cmbackground level at 162⨯. Our measurements strongly suggest a newW cm510/mechanism of propagation of electromagnetic waves through overdense plasmas.一、引言短脉冲强光辐射在几十个飞秒中传播巨大的能量，其与固态密度以及超陡梯度等离子体相互作用已经被研究了。
文章编号:1004-132Ⅹ(2000)12-1389-03大功率激光焊接光致等离子体的光谱分析*苏彦东 博士研究生苏彦东 摘要:大功率激光焊接过程中,光致等离子体的粒子密度及温度对入射激光能量的传输效率及焊缝的熔深都有很大影响。
采用光谱诊断、分析方法,利用谱线相对强度法对激光光致等离子体的温度及电子密度进行了测量与计算,给出了实验条件下光致等离子体电子密度与激光焊接线能量及焊接熔深的量化关系。
关键词:激光焊接;光致等离子体;光谱分析;辐射强度中图分类号:TG 456.7 文献标识码:A收稿日期:1999—06—15基金项目:国家自然科学基金资助重点项目(59836220) 为了使激光焊接过程中,工件最大限度地吸收入射激光能量、增大熔深、提高焊缝深宽比、改善焊缝成形,深入研究激光焊接光致等离子体与激光的相互作用机理是十分重要的。
通过对激光等离子体的光谱诊断结果的分析、计算,可以得到不同焊接条件下等离子体温度、电子密度的变化情况。
由于在局部热力学平衡情况下,光致等离子体由自由电子、带正电的离子及少量未电离的原子和分子组成,其中电子密度与带正电的离子密度被认为是相等的,所以在本实验研究中对光致等离子体谱线强度测量与分析并计算电子密度,可以直接反映光致等离子体粒子密度的大小,获得对焊缝熔深影响的量化关系。
1 实验系统实验研究采用的激光焊接设备为M L -108型横流多模CO 2激光器,额定输出功率为9kW 。
光束发散角小于2m rad 。
焊接试件选取130mm ×60mm ×8mm 的1Cr18Ni9Ti 不锈钢。
光谱诊断系统M odel ST -133,CCD -128多通道光谱分析仪,可同时采集6路光谱信息。
激光焊接光致等离子体的光谱诊断系统见图1。
2 实验测试与计算结果分析2.1 实验测试对不同焊接条件下的光致等离子体光谱图进行了测试分析。
图2为激光输出功率为7kW 、焊接速度为1m /min 时的激光焊接等离子体谱图。
文章编号:0258-7025(2007)12-1621-04离焦量对空气中纳秒激光打孔效率的影响王广安,章玉珠,倪晓武,陆 建(南京理工大学理学院应用物理系,江苏南京210094)摘要 用波长1.06L m,脉冲半峰全宽(F WH M )约10ns 的N d B YA G 激光照射在薄铜靶上,研究了打孔效率同离焦量之间的关系。
实验中脉冲能量分别为26mJ,52mJ,85mJ,204m J 和274mJ,在各脉冲能量下,改变离焦量,测出相应的打孔效率。
结果表明,离焦量是影响打孔效率的重要因素;实际打孔过程中,采用较低的激光功率密度和+3~+4mm 的离焦量是合理的选择。
当离焦量d <0时,打孔效率主要由激光照射产生的热烧蚀、等离子体屏蔽两个物理机制决定;当离焦量d >0时,打孔效率是激光照射产生的热烧蚀、等离子体屏蔽和焦斑处空气等离子体辐射的促吸收效应共同作用的结果。
关键词 激光技术;纳秒脉冲激光;打孔效率;离焦量中图分类号 V 261.8 文献标识码 AEffect of Deviation Distance to Focal Spot onNanosecond -Pulsed -Laser Drilling Rates in AirWANG Guang -an,ZH ANG Yu -zhu,NI Xiao -w u,LU Jian(D ep ar tment of A p p l ied P hy sics ,N anj ing Univ er sity of Science &T echnology ,N anj ing,J iangsu 210094,China)Abstract T he effects of deviat ion dist ance fro m the focal spot t o the tar get surface (d)on nanoseco nd -pulsed -laserdr illing rates under differ ent pulse ener gy w ere experimentally studied.T he laser o per ated at a w aveleng th o f 1.06L m and pulse w idth o f 10ns (full w idth at half max imum).Pulse ener gy of 26,52,85,204and 274mJ w as used r espectiv ely.T he drilling rate was measured under differ ent pulse energ y and d value.T he experimental results show that d is one of the im po rtant aspect s affect ing laser dr illing r ate,and that it is a reasonable choice of using relat ively low intensit y laser pulses and d at +3~+4mm.W hen d <0,the drilling rate is mainly deter mined by laser -induced thrermal ablatio n and shielding of plasma.A nd when d >0,the dr illing rate is mainly det ermined by ther mal ablat ion,shielding of plasma and pro moting abso rption induced by ir radiation fro m the plasma at the beam waist.Key words laser technique;nanosecond pulsed laser;dr illing rate;deviat ion distance to focus spot收稿日期:2006-12-12;收到修改稿日期:2007-04-12 基金项目:国家自然科学基金(60578015)资助项目。
Applied Physics 应用物理, 2020, 10(1), 85-90Published Online January 2020 in Hans. /journal/apphttps:///10.12677/app.2020.101010Effect of the Distance from the FocusingLens to the Target Surface on the InfraredSpectrumYanming Ma, Xingsheng Wang, Xun Gao, Jingquan Lin*Ultrafast Optics Laboratory, Changchun University of Science and Technology, Changchun JilinReceived: Dec. 25th, 2019; accepted: Jan. 8th, 2020; published: Jan. 15th, 2020AbstractNd:YAG nanosecond pulsed laser was used to induce the aluminum target to generate plasma. By changing the distance from the focusing lens to the target surface (LTSD), the intensity of the atomic spectrum and the change of the plasma morphology were observed. In the wavelength range of the experimental study, the spectral lines we discussed are O I 1128 nm, N I 1249 nm, and Al I 1312 nm. The results show that the intensity of the spectral line changes with the change of LTSD. For a focusing lens with a focal length of 75 mm, the spectral intensity of O and Al reaches the maximum at LTSD of 70 mm, and the spectral line of N is the maximum at the focal point of the target surface.KeywordsIR, Nanosecond Pulsed Laser, Lens to Sample Surface Distance, Aluminum聚焦透镜到靶材表面距离对等离子体红外光谱的影响马彦明，王兴生，高勋，林景全*长春理工大学超快光学实验室，吉林长春收稿日期：2019年12月25日；录用日期：2020年1月8日；发布日期：2020年1月15日摘要使用Nd:YAG纳秒脉冲激光诱导铝靶材产生等离子体，通过改变聚焦透镜到靶材表面的距离(LTSD)，观*通讯作者。
保护条件变化的激光焊接等离子体光谱分析杜笑;杨立军;刘桐;焦娇;王会超【摘要】保护气体在激光焊接过程中起重要的作用，保护条件的改变对焊接质量会有显著地影响。
研究Nd∶YAG激光焊过程中保护条件的变化对激光等离子体的电子温度和电子密度等特征参数的影响，通过设计分步减小保护气流量的激光焊试验进行规律性研究，通过模拟实际可能发生的保护不良的激光焊试验进行验证性研究。
在试验研究过程中，利用光谱仪采集激光焊接过程中产生的光致等离子体的光谱信息，通过相对光强法计算不同保护条件下等离子体的电子温度，通过斯塔克展宽机制计算不同保护条件下等离子体的电子密度。
研究结果表明，保护条件的改变对Nd∶YAG激光焊接过程中产生的光致等离子体的电子温度和电子密度有重要影响，随着保护条件的变化，光致等离子体的电子温度和电子密度的平均值会发生变化，其波动幅度也会发生变化。
在保护良好的条件下，等离子体的电子温度和电子密度均较小，且波动幅度也较小；在保护不良的条件下，等离子体的电子温度和电子密度都比较大，且波动幅度也比较大，这种变化的特征有助于对激光焊接过程进行质量监控。
%The shielding gas plays an important role in the laser welding process and the variation of the protecting conditions has an obvious effect on the welding quality .This paper studied the influence of the change of protecting conditions on the parame‐ters of laser‐induced plasma such as electron temperature and electron density during the laser welding process by designing some experiments of reducing the shielding gas flow rate step by step and simulating the adverse conditions possibly occurring in the actual Nd∶YAG laser welding process .The laser‐induced plasma was detected by a fiber spectrometer to get the spectral data . Sothe electron temperature of laser‐induced plasma was calculated by using the method of relative spectral intensity and the elec‐tron density by the Stark Broadening .The results indicated that the variation of protecting conditions had an important effect on the electron temperature and the electron density in the laser welding .When the protecting conditions were changed ,the average electron temperature and the average electron density of the laser‐induced plasma would change ,so did their fluctuation range . When the weld was in a good protecting condition ,the electron temperature ,the electron density and their fluctuation were alllow .Otherwise ,the values would be high .These characteristics would have contribution to monitoring the process of laser w elding .【期刊名称】《光谱学与光谱分析》【年(卷),期】2016(036)001【总页数】5页(P15-19)【关键词】激光焊;激光等离子体;光谱诊断;电子温度;电子密度【作者】杜笑;杨立军;刘桐;焦娇;王会超【作者单位】天津大学材料科学与工程学院，天津 300072;天津大学材料科学与工程学院，天津 300072; 天津大学天津市现代连接技术重点实验室，天津300072;天津大学材料科学与工程学院，天津 300072;天津大学材料科学与工程学院，天津 300072;天津大学材料科学与工程学院，天津 300072【正文语种】中文【中图分类】TG403激光等离子体的产生是激光焊接过程中重要的物理现象[1]，其与激光的相互作用对激光焊过程有直接的影响。
书山有路勤为径，学海无涯苦作舟
离焦量对空气中YAG 激光诱导Cu 等离子体空间特性的
影响
利用Nd: YAG 脉冲激光在空气中烧蚀Cu 靶，产生激光等离子体羽，通过改变离焦量获得相应的等离子体的空间谱;用光谱学方法分析了三种离焦量下空间谱线结构和空间等离子体的电子温度演化规律;并对等离子体光谱的特性和产生机制进行了讨论。
结果表明：离焦量对等离子体的谱线强度、谱线结构、电子温度的空间特性都有影响，特征谱强度最大值出现在空间位置1.0mm 附近，离焦量为-2mm 时电子温度最高。
自1960 年激光诞生以来，它凭借其独特的优势，能够将能量在超短的时间和特定的空间完成与物质的作用，已经在气体、液体、复合材料、金属和半导体等材料表面和内部实现了加工、打孔、光刻、雕刻、表面改性、淬火和打标等形式，为制备各种结构和功能性材料以及在全息模拟、激光武器、激光医疗、生物工程等方面取得新的进展，引起了研究人员的高度关注和研究兴趣。
激光作用到物质表面容易形成高密度等离子体，其形成机制比较复杂，涉及很多动力学过程，直接观测相对困难，而用发射光谱法就可以避免探测的困难，这种方法具有分析时间短、灵敏度高、处理简单、可远程测量等优点，而且对分析样品具有极小的损坏性，又可以用来探测等离子体内部的特征信息，已经在真空镀膜、元素的痕量微区分析、医疗卫生、国家安全、环境监测、文物保护等各个领域得到成功应用。
激光等离子体的光谱特性又与各种测量有关，比如激光的波长、功率、脉宽、能量阈值、靶材、聚焦位置、环境气体、真空度等，而实验环境通常在大气中完成，因此分析在大气中通过改变离焦量研究激光等离子体的特性具有实际意义。
本文采用1064 nm 的YAG 脉冲激光,通过变。
