高强度细晶粒碳素钢焊接接头熔合区附近的显微组织及精细结构

研究了高强度细晶粒碳素钢焊接接头熔合区附近的显微组织及精细结构。结果表明,在熔化极混合气体保护焊接条件下,该钢材的熔合区宽度为20～40μm。随着焊接线能量的减小,熔合区的整体硬度提高。熔合区焊缝侧针状铁素体的形态与焊接线能量有关。氧化物夹杂大多位于针状铁素体边界。在熔合区母材侧,下贝氏体中的碳化物呈多种形态,并受焊接规范的影响。     

“复合焊”焊缝显微组织分析

采用光学金相显微镜对“复合焊”焊缝进行组织分析,以此作为探求焊接参数,控制施焊工艺,提高焊缝组织性能的依据。     

激光拼焊异种超高强钢组织和力学性能

 汽车轻量化后对安全性和碰撞吸能性提出了更高要求,从而促进了高强、吸能材料及其拼接技术的发展。以汽车安保件之一的汽车B柱为研究对象,采用能满足要求的DP980双相钢和22MnB5热冲压成型钢异种材料进行激光拼焊,研究焊接热输入对焊接接头显微组织与力学性能的影响。通过保持激光输出功率不变(1.3 kW)改变焊接速度的方法控制焊接热输入,考察焊接热输入与拼焊接头组织和力学性能之间的关系。利用光学显微镜、扫描电子显微镜、显微硬度测试仪和拉伸试验机研究接头不同亚区的组织和性能。结果表明,当焊接速度为16~26 mm/s时,均获得了完整而无缺陷的熔化区组织;随着焊接速度的提高,不仅焊缝表面凹陷逐步改善,并且焊接热影响区宽度也随之减小。硬度测试表明,接头中存在明显的软化区域,主要分布在DP980侧热影响区的回火区和不完全相变区,而DP980侧热影响区的细晶区、粗晶区、22MnB5侧热影响区以及焊缝金属区的硬度则有所增加,形成了焊接接头的硬化区。拼焊接头在能形成完整接头的条件下抗拉强度保持为576~597 MPa,断裂均发生在22MnB5侧的母材区,断裂时有明显的颈缩现象;接头断后伸长率为11.9%~15.5%,介于DP980母材(11%)和22MnB5(22%)母材的断后伸长率之间;研究还表明,焊接热输入越大,焊接接头相同区域的组织越粗大。     

激光拼焊汽车板的应用现状与发展前景

目前激光拼焊技术在汽车车身设计中被广泛采用。拼焊板是将几块不同材质、不同厚度、不同涂层的钢板焊接成一体的钢板,以满足零部件对材料性能及厚度的不同要求。激光拼焊技术与热冲压成形技术、液压成形技术均为超轻车体项目中重点推荐的三大技术,具有减重、提高安全性、节省材料等多项优势,为汽车用材技术发展的一大趋势。主要介绍了激光拼焊板技术的发展、特点、优势、亟待解决的问题、研究热点、应用现状以及国内市场的发展前景。     

22MnB5与HC340LA/HC340/590DP激光拼焊淬火后组织与性能分析

近年来热成型钢在汽车行业被广泛引入,成为汽车轻量化解决方案的一个重要组成部分.为满足碰撞法规安全与吸能要求,激光拼焊技术等改进的热成型技术已被广泛应用,采用HC340LA、HC340/590DP分别与22MnB5薄板试样进行激光拼焊,利用GLEEBLE 3500热模拟试验机进行淬火试验,对拼焊试样淬火后组织与性能进行分析,实验结果表明:焊缝均不是淬火件的薄弱区,HC340/590DP与22MnB5搭配强度与极限延伸率过渡更为合理,研究结果对实际应用有一定的指导意义.     

低碳低合金钢焊缝金属的显微组织及其影响因素

低碳低合金钢焊缝金属的显微组织基本上包括先共析铁素体、针状铁素体、侧板条铁体、少量的粒状贝氏体和马氏体。分析了这些组织的形成条件及特点,焊缝金属化学成分和冷却速度是影响焊缝金属组织的主要因素,阐述了各种组织的形核位置。低碳低合金钢焊缝金属最理想的组织是获得大于６５％的针状铁素体,其平均板条尺寸约为１μｍ。     

激光焊接速度对焊缝组织和硬度分布的影响

利用激光焊接工艺焊接核级不锈钢,通过改变激光焊接速度得到不同的焊接接头.采用金相显微镜、扫描电子显微镜等手段研究了熔深比、δ/γ比、组织形貌以及焊缝中各相的成分.通过显微硬度测试了焊缝接头上硬度分布.随着焊接速度的增加,焊缝熔深比线性增加,焊缝中δ-铁素体含量增加,岛状组织增多,板条状组织增多,蠕虫状组织减少,焊缝区的平均硬度值增加.     

基于DEFORM软件的U型梁激光拼焊件热成形仿真分析

采用DEFORM软件对U型梁激光拼焊件进行计算机仿真,拼焊材料为热成形钢800HS与1500HS,研究热成形过程中温度场、相组成的变化过程,并对保压、模具间隙、冷却能力等热成形主要工艺参数对热成形效果的影响予以讨论,获得了全工序的温度场、相组成的变化规律,给出了热成形主要工艺参数对热成形效果的影响,其中模具间隙是决定热成形淬火性能的关键因素,冷却水道是保障连续模淬的关键措施。经实际生产验证,仿真分析符合性较好,对激光拼焊件热成形实际生产具有一定的指导意义。     

低合金高强钢激光—电弧复合焊焊缝组织及性能研究

激光—电弧复合焊兼具表面成形较好、熔深较大的特点,在中厚板焊接中获得广泛应用,但激光复合焊时,焊缝冷却速率较快,焊缝淬硬倾向较强,在中厚板低合金高强钢焊接时应用受限.针对宝钢生产的BG890QL低合金高强钢进行激光—电弧复合焊接,研究焊缝组织的淬硬倾向,结果表明:激光—电弧复合焊接接头柱状晶组织特定生长方向明显,但焊缝中心和顶部存在等轴晶.室温和-40℃时,焊缝处的冲击功分别为58 J和40 J,热影响区的分别为147 J和66.5 J,冲击性能均能满足要求.激光—电弧复合焊低合金高强钢可以获得强韧性较好的焊缝及热影响区组织,满足工程应用需求.     

Fine Microstructure of Bainitic Ferrite in Bainitic Steel

Asbainiticsteelspossesshighhardness ,highstrength toughness ,highwearresistanceandhighhardenability ,theacademicandengineeringcircleshavepaidcloseattentiontotheinvestigationoffinemicrostructure[1,2 ] .However ,thefinemicrostruc tureofbainiticsteelsisnotdeterminedyet .Thefinemicrostructuresofmediumandmedium highcarbonbainiticsteelswereobservedandanalyzedbyhighresolutionelectronmicroscope (HREM ) ,andthere sultsshowthatthereareretainedausteniticfilmsatdifferentlevelstructureunitboundaries .The…     

Laser Welding of Ultra-Fine Grained Steel SS400

Steeliswidelyusedbecauseofitsgoodcompre hensive properties ,plentyofresourceandlowerprice .Thestrengthandtoughnessaretwoimpor tantpropertiesofsteels ,andpeoplemakeeffortstoincreasetheirvalues .Addingalloyingelementandcontrollingmicrostructurearetwobasicwaystoac complishtheaim .Therefinedmicrostructureob tainedbyprocessingtechniqueenablesthestrengthandtoughnessofsteeltobeincreasedwithoutaddingalloyingelementandtheratioofperformance costtobeincreased .Theultra finegrainedsteelshavefer ritegrains…     

Influence of Ti on Weld Microstructure and Mechanical Properties in Large Heat Input Welding of High Strength Low Alloy Steels

The influence of Ti on weld microstructure and mechanical properties in large heat input welding of high strength low alloy steels is investigated.The results indicate that a moderate amount of Ti is still effective for grain refinement even under larger heat input and a large amount of acicular ferrite(AF)is formed in the weld metal when Ti content is within 0.028%-0.038%.With increasing Ti content,proeutectoid ferrite in the weld metal decreases,whereas bainite and M-A constituent increase.The type of inclusion in the welds varies from Mn-Si-Al-O to TiMn-Al-O and finally to Ti-Al-O as Ti content increases from 0up to 0.064%.As for adding 0.028%-0.038% Ti,high weld toughness could be attained since most inclusions less than 2μm which contain Ti2O3 provide the effective nuclei for acicular ferrite formation.However,the toughness of the weld metals severely reduces when Ti content is over the optimum range of 0.028%-0.038%.     

Ti-Al-Fe低成本钛合金TIG焊焊接组织和性能研究

研究了Ti-Al-Fe低成本钛合金钨极氩弧焊焊接接头的内部质量、组织和力学性能,并与TC4钛合金进行了比较。结果表明,Ti-Al-Fe低成本钛合金焊缝表面质量良好,焊缝内部融合良好,无焊接缺陷,可焊性好; 2种合金的焊缝区宏观组织均由粗大的柱状晶和少量等轴晶组成,Ti-Al-Fe合金柱状晶组织较细,晶内由针状次生α相和少量的长条状初生α相组成; 2种合金热影响区均为粗大的等轴晶,晶内由大量初生α相和少量针状次生α相及残余β相组成; Ti-Al-Fe低成本钛合金焊缝抗拉强度达到1 204 MPa,比TC4钛合金高111 MPa。     

Microstructure and Properties Analysis of Laser Welding and Laser Weld Bonding Mg to Al Joints

Laser welding and laser weld bonding (LWB) Mg to Al joints were obtained in different welding parameters. The penetrations and microstructures of these kinds of joints changed with the increasing of pulse laser power density. Both laser welding and LWB Mg to Al joints with the best properties were obtained in conductive welding mode. In laser welding Mg to Al joint, several intermetallics formed at the bottom of the fusion zone, where some cracks were generated. In laser weld bonding Mg to Al joint, the decomposition of the adhesive caused a baffle effect on the diffusion between the Mg and the Al. The intermetallics formed in the middle of the fusion zone, and the thickness of Mg₁₇Al₁₂ layer was approximately 10 to 20 μm and the Mg₂Al₃ layer was less than 5 μm, which influenced the property of the joint less.     

Study of Bake Hardening Effect on Laser Welded Hot Rolled Ferrite‐Bainite Dual Phase Steels

The influence of bake hardening (BH) effect on laser welded hot rolled ferrite‐bainite dual phase steel (FBS) with respect to the process conditions was investigated. The samples were firstly laser welded and then pre‐strained. Pre‐strained the samples with defined degrees of deformation and a subsequent aging treatment leads to enhanced hardness and strengthening for both conditions. The microstructure of the fusion zone (FZ) and heat affected zone (HAZ) was studied. A high volume fraction of martensite could be observed in the FZ as well as in the HAZ. Both steels exhibited a clear BH effect in both, the as‐received and the laser welded conditions. The BH effect is more pronounced in the pre‐strained laser welded condition.     

MgO对以细磁铁精矿为主的烧结矿微观结构的影响

研究了MgO对以细磁铁精矿为主的烧结矿显微结构的影响。显微结构分析表明：烧结矿MgO的质量分数从1．4%提高到2．3％时,MgO对烧结矿微观结构具有明显的影响。低MgO时,未氧化的Fe3O4及其部分氧化生成的Fe2O3与铁酸钙粘结相形成了烧结矿良好的显微结构,其烧结矿强度良好。高MgO时,烧结矿生成了大块再结晶磁铁矿,同时生成了铁酸镁和镁铁橄榄石等一系列含镁矿物,MgO稳定了磁铁矿和含镁矿物的晶格,这些矿物与赤铁矿、铁酸钙等共存和互连。但MgO矿化需要较高的烧结温度和较长的高温保持时间,垂直烧结速度和利用系数有明显的降低。     

LF21薄板搅拌摩擦焊工艺研究及微观组织分析

采用搅拌摩擦焊接方法对厚度为1．5mm的LF21薄板铝合金板在进行焊接试验,首次提出搅拌头旋转速度为5000r／min时的焊接工艺,实验结果表明：在焊接速度为70～105mm／min,压入量适中,并采用喷气冷却,可以获得较好的焊接接头,抗拉强度达到最大值111．530MPa。焊缝中存在3个组织变化区,其中焊核区内是细小均匀的等轴晶,焊缝两侧热机影响区组织存在较大差异,热影响区组织发生了回复、再结晶和粗化。