基于数值模拟的激光拼焊板渐进成形性能研究

渐进成形技术是近年发展起来的一种新的板料成形方法,将该技术应用到激光拼焊板成形领域的研究还很少。以某圆台零件为研究对象,建立了激光拼焊板有限元模型。通过正交试验研究了工具头直径、下压量、拼焊板焊缝位置和板厚组合对激光拼焊板的成形性能的影响。结果表明,焊缝位置对激光拼焊板成形极限的影响最为显著,其次为下压量、板厚组合和工具头直径,并得出了最优工艺参数组合。在保证零件加工精度及满足设备成形能力的前提下,尽量提高下压量不仅有助于提高激光拼焊板成形效率,还能有效提高成形极限。结果能为渐进成形工艺参数的选择提供参考。     

液压夹紧装置在差厚激光拼焊板冲压中的研究

破裂和焊缝移动是差厚激光拼焊板成形中存在的两个主要问题.利用塑性力学,对焊缝移动进行了力学分析.为提高激光拼焊板的成形性能,设计了液压夹紧装置,并解释了装置的原理.通过门内板拼焊板的冲压成形实验,比较了使用液压缸前后拼焊板的焊缝移动变化和板厚变化情况.实验表明,夹紧装置能有效地控制差厚拼焊板成形中焊缝的移动,能减少薄侧板材的变薄,从而提高拼焊板的整体成形性能.     

激光拼焊板方盒件及其板料优化设计分析

成形性能的提高对拼焊板车身覆盖件以及结构件冲压成形有重要意义。通过对激光拼焊板方盒件及其板料对成形过程的影响研究,并采用基于板料厚度比、坯料形状和尺寸等板料参数正交设计的成形优化方法,提高激光拼焊板方盒件冲压成形性能。研究和冲压试验表明：当厚度比较小时,破裂出现在薄侧圆角处,而厚度比较大时,破裂出现在薄侧焊缝处;方形坯料拼焊板的成形性能明显低于圆形坯料形状的拼焊板;板料正交设计方法对拼焊板方盒件冲压成形优化是有效可行的。     

激光拼焊板在汽车车门内板上的应用

介绍了激光拼焊板的技术特点及成形工艺,阐述了激光拼焊板应用在车门内板上的模具设计与制造过程。     

曲线焊缝激光拼焊板胀形成形性研究

拼焊板成形技术是目前汽车车身轻量化的重要手段之一,焊缝形状及位置是影响拼焊板成形极限的两个重要因素,针对此,该文利用圆球胀形试验,对厚度比、焊缝形状对激光拼焊板极限成形高度的影响进行了研究,并对影响规律进行了分析,从而为拼焊板的设计开发开阔了思路。     

激光拼焊板冲压成形中焊缝开裂原因分析与避免措施

针对用激光拼焊板冲压成形汽车前门内板生产过程中出现制件开裂的现象,分析了内板焊缝区域冲压开裂的原因,通过对板料的力学性能分析、焊缝杯突试验、金相组织分析、料厚减薄分析等,对避免激光拼焊板焊缝区冲压成形过程中开裂提出了有效可行的解决措施。     

基于BP人工神经网络模型的激光焊缝宽度预测方法

激光焊缝宽度是考核激光拼焊板质量的重要指标之一,直接影响到拼焊板的成形性能.因此,通过对激光焊缝宽度进行预测可以达到焊接工艺参数优化的目的,以提高拼焊板的焊接质量与成形性能.本文利用BP人工神经网络技术建立了焊缝宽度预测模型,该模型可以实现对焊缝宽度的有效预测,预测精度达到96%以上,具有较好的工业实用价值.     

铝合金拼焊板充液成形技术研究

铝合金拼焊板充液成形技术是拼焊板成形技术和充液成形技术的综合运用,兼具了这2种先进成形技术的双重优点,在汽车、航空航天等领域具有广泛的应用前景。介绍了铝合金拼焊板焊接方法、激光焊接的特点与难点,探讨了拼焊板充液成形技术的原理、特点及国内外研究现状,指出了开展此项研究的必要性和重要意义。     

ST14钢激光拼焊板焊缝组织及成形性能分析

对1.5mm和0.8mm两种规格的ST14钢等厚激光拼焊板焊缝部位进行杯突试验,比较焊缝与母材杯突值;再对由这两种规格组合拼焊的不等厚激光拼焊板进行单向拉伸试验,检验拼焊板经拉伸后的断裂部位;分析焊缝区组织及其硬度变化,研究激光焊接参数变化对ST14钢拼焊板成形性能的影响.结果表明,焊缝深冲性能低于母材,焊缝杯突值受焊接速度影响,随焊接速度增加而增加;激光焊缝抗拉强度高于母材;对于1.5 mm拼焊板,提高焊接速度,加快焊缝冷却,有利于生成细小的针状铁素体,可提高激光拼焊板的成形性能;而0.8 mm板焊缝生成晶粒细小的粒状贝氏体组织,可使焊缝区材料成形性能接近母材;焊缝及其热影响区的硬度高于母材硬度.     

基于偏最小二乘回归模型的激光焊缝宽度预测与控制方法

激光焊接焊缝是激光拼焊板成形性能的重要影响因素之一,同时也是导致拼焊板在冲压过程中出现破裂失效的导火索.因此,为了优化焊接工艺以及激光拼焊板成形性能就必须对焊缝宽度加以预测与控制.利用有限元软件对激光焊接过程进行三维动态温度场模拟,通过分析试验钢板节点温度分布情况,计算出焊缝宽度.在此基础上,利用偏最小二乘同归方法建立了激光焊缝宽度预测模型.运用本文预测模型,焊缝宽度预测相对误差均在5%以下,充分验证了该预测模型的合理性及适用性.     

Tailored blank welding between low carbon steel sheet and STS 304 stainless steel sheet by CO2 laser beam

A basic reseach of tailored blank welding between a low carbon steel sheet and a STS 304 stainless steel sheet was carried out with CO₂ laser beam. The materials used in this work were a low carbon steel sheet with a thickness of 0.9 mm and a STS 304 stainless steel sheet with the same thickness. Experiments were carried out by applying the Taguchi method to obtain optimized conditions in order to apply this tailored blank laser welding method in the practical manufacturing process. In order to compare the laser welding results with the conventional welding process, GTA welding was carried out for the same materials. Optical microscopy, SEM and XRD analyses were performed to observe the microstructures and to analyze the various phases. A tensile test, hardness test and Erichsen test were performed to evaluate the formability of welded specimens. In addition, immersion test was carried to estimate corrosion resistance. A WDS analysis showed that laser welding resulted in almost the same dilution of both low carbon steel and stainless steel in welded metal, meanwhile, GTA welding resulted in more dilution of stainless steel due to its slower heat conductivity. The formability of the laser welded specimen reached 83% of that in base metal. On the other hand, it was 63% in the case of GTA welding. During the tension test, base metal was fractured in the case of a laser welded specimen, meanwhile the welded zone was fractured in the case of the GTA welded specimen. The corrosion test showed that weight loss per unit area was less in the laser welded specimen than that of the GTA welded specimen.     

Comparison of formability of friction stir welded and laser welded dual phase 590 steel sheets

Abstract

The formability of welded dual phase 590 (DP 590) steel sheets was investigated, using both friction stir welding and laser welding. Similar and dissimilar gauge sheets were joined using both processes. The laser welded sheets were produced under process conditions typical of industrial production of tailor welded blanks. The friction stir welded specimens were produced in a lab, where different tool rotational speeds and translation speeds were investigated in order to obtain good weld properties. The formability of the welded sheets was evaluated using a series of mechanical tests, including transverse tension and plane strain formability testing. Friction stir welded specimens performed about the same as laser welded specimens in transverse tension testing; however, hardness profiles showed that the laser welds had greater peak hardness than the friction stir welds. Therefore plane strain formability tests were performed with the welds oriented along the major strain direction. When this type of weld stretching was performed the friction stir welded sheets were shown to be ～20% more formable than the laser welded sheets.     

A study of tailored blank welding between mild steel sheet and zn-coated steel sheet by CO2 laser beam

Research was conducted on tailored blank welding between mild steel sheet and Zn-coated steel sheet using CO₂ laser beam. The materials used in this study were low carbon steel sheets with a thickness of 1.2 mm and Zn-coated steel sheet with the same thickness and 6.3 μm Zn coating. Experiments were conducted by applying the Taguchi method to obtain optimum conditions for the application of this tailored blank laser welding method in practical manufacturing processes. Optical microscopy, XRD, SEM and TEM analysis were performed to observe the microstructures and to determine the structures of welded zone. In addition, mechanical properties were measured by the microhardness test, tensile test and Erichsen test to evaluate the formability of the welded specimen. There was no trapped Zn in the fusion zone, and the phases of this region consisted of polygonal ferrite, quasi-polygonal ferrite, banitic ferrite and martensite. The elongation value of welded specimen was more than 80% of the value in substrate metal, and the LDH value was more than 90% of the value in substrate metal.     

Determination of laser weld properties for finite element analysis of laser welded tailored blanks

Abstract

The present paper details two techniques that were employed to determine laser weld material properties, and outlines how the weld properties were used in the finite element analysis simulation of simple small scale axisymmetric tests. From these simulations, an understanding of some fundamental laser welded tailored blank formability issues was gained, which would otherwise have required substantial practical tests to be conducted. The materials studied in the present paper were high strength steels, including a relatively newly developed ultrahigh strength steel, for application in structural body in white components.     

激光焊接的裁焊板及其在汽车中的应用

介绍了激光焊接用于汽车裁焊板的新技术。使用裁焊板可以实现汽车部件尺寸和材质的优花配合。与滚压缝焊相比，激光焊接具有焊接质量高、适应性广、生产费用和维护费用低的优点，特别适合进行裁焊板的焊接加工。激光焊接裁焊板的技术问题主要有：采用激光切割坯板方案的可行性、接头的成形性、焊接质量的控制和大板拼接变形的控制。     

快速冷却对DP1000双相钢激光焊接接头性能的影响

激光焊接DP1000双相先进高强钢的过程中,普遍存在焊接热影响区的软化现象,热影响区的软化严重影响了焊接结构的成形和使用性能. 为了能提高焊接接头的成形和使用性能,采用快速冷却的方式来改善其焊接热影响区的软化问题. 通过拉伸试验、显微硬度测试、扫描电镜和光学显微镜等手段对比研究了1.5 mm厚DP1000双相钢板有无快速冷却的焊接接头中组织和性能的变化. 结果表明,在快速冷却条件下,激光焊接DP1000双相钢的接头热影响区软化区较空冷焊接的窄,软化现象有所改善,强度和塑性均有所提高.     

Nd:YAG激光焊接800 MPa TRIP钢的接头组织与性能

采用Nd:YAG激光对强度为800MPa,厚度为1.2mm的TRIP钢板进行焊接.研究焊接速度对焊缝外观和截面成形的影响及接头的组织特点、硬度、强度和成形能力.激光功率相同,焊接速度较低时焊缝易产生气孔,速度较高时易发生飞溅;焊接速度对焊缝熔深及熔宽也有影响.焊缝组织主要由马氏体构成,从焊缝、热影响区到母材,组织中马氏体含量下降,接头的最高硬度出现在焊缝或热影响区.在平行于焊缝方向,焊接接头的抗拉强度高于母材,垂直于焊缝方向,接头的抗拉强度与母材相当.由于焊缝中出现马氏体,接头的塑性和韧性降低,板材的冲压成形能力下降.     

CO_2激光焊接600MPa DP钢接头组织与性能

采用CO2激光对抗拉强度为600MPa,厚度1.4mm的DP钢进行焊接.研究焊接速度对焊缝外观和截面成形的影响、接头的组织特点、硬度、强度和成形能力.结果表明,激光功率相同,焊接速度较低时焊缝易产生气孔,焊接速度较高时易发生飞溅;焊接速度对焊缝熔深及熔宽也有影响.焊缝区组织主要由马氏体构成,从焊缝、焊接热影响区到母材,组织中马氏体含量下降,接头的最高硬度出现在焊缝或热影响区.在平行于焊缝方向,焊接接头的抗拉强度高于母材,垂直于焊缝方向,接头的抗拉强度与母材相当.由于焊缝出现马氏体组织,接头的塑性和韧性降低,板材的冲压成形能力下降.     

镀锌钢板的CO_2激光焊焊接性(II)

以裁焊板工业生产为背景 ,对汽车用镀锌钢板的CO2 激光切割板坯的CO2 激光焊接的焊缝性能进行了试验研究。试验中的激光焊缝屈服强度都大于母材 ,焊缝金相组织以硬度较软的针状铁素体为特征 ,包含激光焊缝的镀锌钢板仍具有优良的深冲性能 ,在焊缝附近锌层烧损小于 0 .5mm宽。镀锌层具有牺牲保护作用使得激光焊缝不易腐蚀。因此 ,裁焊板的激光焊接工艺可靠 ,从焊接角度看 ,激光切割取代裁焊板生产中剪切工艺是可行的