铝冲压模具的焊接修复工艺研究

采用自制药芯焊丝对H13(4Cr5MoSiV1)钢模具进行焊接修复。用洛氏硬度计、显微硬度计及金相显微镜研究了H13钢的不同焊接材料及焊前预热处理工艺对焊缝组织和强度的影响。结果表明:自制药芯焊丝焊接接头母材及焊缝显微硬度接近,且焊接接头晶粒细小,硬度分布均匀,有效减少了焊缝及热影响区(HAZ)的应力集中现象。自制药芯焊丝中合金元素含量较高且含碳量低,易形成等轴晶粒细化焊缝组织,提高焊缝金属耐磨性。同时,焊前预热工艺可延缓焊后焊缝冷却速度,降低焊缝热影响区显微硬度。     

一种核电核岛主设备用镍基焊丝的研制

通过试验分析了核电核岛主设备用镍基焊丝中各元素对焊丝和焊缝熔敷金属性能的影响.结果表明,随着焊丝中Al,Ti,Mn,Nb元素含量的增加,焊丝的强度、硬度及焊缝金属的抗拉强度增加;随着焊丝中Al,Ti,Nb元素含量的增加,室温焊缝熔敷金属的冲击吸收功增加;随着焊丝中Mn元素含量的增加,焊缝熔敷金属的冲击吸收功降低.通过调整焊丝成分得到了符合核电核岛主设备使用要求的焊缝熔敷金属.     

Al对药芯焊丝CO_2气体保护焊焊缝质量的影响

通过改变药芯焊丝中Al元素含量,获得了一系列CO_2气体保护焊焊缝。基于对焊缝中气孔和夹杂的分析以及力学性能测试,分析了铝对药芯焊丝CO_2气体保护焊焊缝质量的影响。试验结果表明,当焊丝中Al元素含量增加时,焊缝气孔敏感性降低;夹杂数量减少但夹杂体积增大;焊缝强度随Al含量提高先减小后增大,而韧性先增大后减小;当焊丝中Al元素含量为0.48%(质量分数)时,焊缝气孔较少且夹杂较少,焊缝力学性能良好。     

表面处理对铝合金焊丝气孔敏感性的影响

铝合金焊丝洁净度是影响焊缝质量的主要因素之一。研究表面处理对铝合金焊丝气孔敏感性的影响,结果表明,表面处理工艺不同,焊丝氢含量存在差异。未清洗的焊丝,氢含量最高,通过机械抛光方法制备的焊丝氢含量最低;焊丝氢含量与焊缝气孔倾向呈正相关性,随着焊丝氢含量的提高,焊缝气孔形成倾向增加。采用机械法抛光焊丝,减少焊丝氢含量,可防止焊缝气孔的产生。     

5083/6061异种铝合金角焊缝组织与性能分析

采用两种焊丝Al5356和Al4043进行了6 mm厚的5083/6061异种铝合金角焊缝的焊接,对焊缝接头的组织和力学性能分析。试验表明:使用两种焊丝都可以得到成形合格的角焊缝,但热输入较小的焊缝熔深尺寸和焊缝厚度尺寸更为稳定。使用焊丝Al5356的焊缝接头组织晶粒及第二相更细密,焊丝Al5356的工艺适应性更强;焊丝Al5356焊接的异种铝合金的角焊缝强度更高,在5系和6系的异种铝合金焊接结构设计及工程应用中应当优先选择焊丝Al5356。     

激光填丝焊焊丝指向与焊缝成形关系的研究

针对首钢酸轧生产线激光焊接头断裂事故,发现焊缝成形存在不稳定缺陷。利用高速摄影手段,研究了焊丝指向对焊缝成形的影响规律。指出:当焊丝指向熔池中光束位置正下方时,焊缝成形最好,熔化焊丝过渡稳定顺畅;当焊丝指向熔池后方时,焊丝在进入熔池前已被全部熔化,熔滴经历产生、长大到滴落的循环,造成焊缝成形不稳定;当焊丝指向熔池前方时,焊丝熔化不够充分,也会造成焊缝成形的不稳定。分析确定,酸轧生产线焊缝成形不稳定现象由焊丝指向熔池后方所致。最终,制定了防止酸轧生产线焊接接头断裂的工艺措施,解决了接头断裂问题,每月为企业减少损失300多万元。     

不锈钢药芯焊丝中药粉的作用

论述了不锈钢药芯焊丝药粉组成对不锈钢药芯焊丝焊接工艺性的脱渣性、飞溅、焊缝成形、防止焊缝气孔生成、立焊及焊缝颜色等的影响,并对不锈钢药芯焊丝中主要的药粉组成的比例作了简单的定量分析。     

镁合金气保焊的飞溅和气孔：产生机理和消除措施（三）

（续上期）B焊丝产生的气孔与消除鉴于A焊丝表面部分黑斑造成气孔,试验另外采用了一种新品牌的焊丝盘,这种焊丝表面光亮,进行CSC-GMAW焊接时形成的焊缝没有气孔产生,如图15所示。焊丝直径1.2mm,AZ61A焊丝,这里把它命名为B焊丝,是从一个新供应商处订购。这种焊丝到货检验时,表面光洁,无黑斑。然而,采用已经暴露在空气中几个月的B焊焊接方向10mm5mm（B）母材焊缝2焊缝2图15采用B焊丝进行CSC-GMAW制造的焊缝没有气孔产生。A-俯视图;B-纵向横断面。     

高速列车用富氩混合气体保护焊丝的研制

通过试验分析了富氩混合气体保护焊条件下焊丝中各元素含量对焊丝及焊缝金属性能的影响.结果表明:随着焊丝中C,Si,Mn含量的增加,焊丝及焊缝金属的强度均提高,焊缝金属的伸长率和冲击吸收功降低.考虑焊丝的制造工艺、使用性能以及CRH5高速列车转向架对焊接接头服役性能的要求,通过调整焊丝成分得到了符合CRH5高速列车使用要求的焊接接头性能.     

铝合金TIG焊用活性焊丝的研制

研制了两种用于铝合金焊接的活性焊丝:活性涂层焊丝和活性药芯焊丝,分别采用这两种活性焊丝对铝合金进行了活性钨极氩弧焊试验。结果表明,由于活性剂通过焊丝过渡到电弧气氛中,克服了以往在铝合金母材表面手工涂敷活性剂存在的不足;相比而言,采用活性药芯焊丝进行焊接时,焊缝表面成形较好,焊缝熔深明显增加,并且焊缝组织也得到了明显细化。     

Effect of weld metal microstructures on cold crack susceptibility of FCAW weld metal

The effect of microstructures on weld metal cold cracking has been studied using flux-cored are welding (FCAW) wires with a 600 MPa strength level. Two FCAW wires were prepared by controlling the Ni content to allow a sufficient variation in weld microstructures, but with little change in the weld metal strength. The microstructural analysis showed that there was a significant difference in the proportions of the microstructural constituents of the weld microstructure. The 1.5%Ni wire resulted in a weld microstructure with a lower grain boundary ferrite (GF) content associated with an increased proportion of acicular ferrite (AF) than the 0% Ni wire. The GF contents of 0%Ni and 1.5%Ni weld metal were measured to be 19% and 6%, respectively. The cold crack susceptibility of these two FCAW wires was evaluated using the gapped bead-on-plate (G-BOP) test at the two different levels of diffusible hydrogen content As a result of the G-BOP tests, it was demonstrated that the 1.5%Ni wire had better resistance to cold cracking than the 0% Ni wire because its weld deposit had a lower GF phase content. This implies that, in addition to the hydrogen control approach, microstructural modification can be pursued to develop new welding consumables with an improved resistance to cold cracking. In the discussion, the detrimental effect of GF against cold cracking is addressed based on the microstructural characteristics of cold cracks in ferritic weld metal.     

Effect of grain boundary ferrite on susceptibility to cold cracking in high-strength weld metal

Due to the practical limitations of lowering the diffusible hydrogen content of flux-containing welding consumables, it is now felt that modification of the weld microstructure would alleviate the risk of weld metal cracking in multi-pass weld deposits. Thus, this study aimed to identify and evaluate the effect of the weld microstructure on the cold cracking susceptibility of FCAW weld metals and then to provide a basic guideline for designing new welding consumables from a microstructural point of view. In order to identify the parameter(s) that can quantify the microstructural susceptibility of multi-pass weld deposit, two sets of FCAW wires with tensile strength of about 600 MPa were prepared by controlling the Ni content to allow sufficient variation in the weld microstructure, but with little change in weld metal strength. The cold crack susceptibility of those two chemistries was evaluated by a multi-pass weld metal cracking test at various levels of diffusible hydrogen content. All of the cold cracks developed were Chevron-type, and the occurrence of such cracks depended upon the proportion of grain boundary ferrite (%GF) as well as the diffusible hydrogen (HD) content. In fact, at the same level of HD, higher Ni (1.5%Ni) wire showed better resistance to cold cracking than lower Ni (0%Ni) wire even though the latter was stronger and also higher in carbon equivalent. This result could be explained solely by the difference in grain boundary ferrite content between those two welds since Chevron cracking preferentially initiates at and propagates along grain boundary ferrite. Therefore, we propose the use of a value of %GF as a parameter to quantify the microstructural susceptibility of ferritic multipass weld deposit with a strength level of about 600 MPa. It was further suggested that, in addition to the hydrogen control approach, microstructural modification in the form of reducing the %GF can be pursued to develop welding consumables with improved resistance to cold cracking.     

V含量及回火工艺对高强钢TIG焊熔敷金属组织性能的影响

采用四种不同V含量焊丝对高强钢板进行钨极氩弧焊试验，焊后对熔敷金属进行640 ℃保温2 h的回火处理. 研究了V含量和回火处理对熔敷金属微观组织及力学性能的影响. 结果表明，焊态及焊后回火态条件下，随着V含量的增加，熔敷金属强度升高，延伸率和冲击功降低，经回火处理后，不含V熔敷金属内晶界处析出M₂C碳化物，而含V熔敷金属内析出弥散分布的VC析出相，焊后回火过程中位错回复引起基体软化的作用高于M₂C及VC的析出强化作用，导致回火后强度降低，断后伸长率冲击吸收能量升高. 细小VC具有阻碍位错运动的作用，导致回火后含V熔敷金属仍保留较高的位错密度. 实际应用中应根据熔敷金属性能要求合理选择V含量及焊后回火工艺.     

Chemical activity of a ceramic flux in surfacing with 15Kh18N12S4TYu strip

Abstract

The strength and notch impact toughness properties of pure weld metal and weld metal from welded joints deposited from the TGL 39 671 filler wires 10 MnSi 6, 10 MnSi 8 and similar welding wires are evaluated. The notch impact toughness is found to be determined in the main by the manganese content of the welding wires, lower manganese contents resulting in higher toughness values.     

Dissimilar metal joining of aluminum alloy to galvanized steel with Al-Si, Al-Cu, Al-Si-Cu and Zn-Al filler wires

Aluminum alloy sheets were lap joined to galvanized steel sheets by gas tungsten arc welding (GTAW) with Al-5% Si, Al-12% Si, Al-6% Cu, Al-10% Si-4% Cu and Zn-15% Al filler wires. Different amounts of Si, Cu and Zn were introduced into the weld through different filler wires. The effects of alloying elements on the microstructure in the weld and tensile strength of the resultant joint were investigated. It was found that the thickness of the intermetallic compound (IMC) layer decreased and the tensile strength of the joint increased with the increase of Si content in the weld. The thickness of the IMC layer could be controlled as thin as about 2 μm and the tensile strength of the dissimilar metal joint reached 136 MPa with Al-12% Si filler wire. Al-Si-Cu filler wire could result in thinner interfacial layer than Al-Cu filler wire, and fracture during tensile testing occurred in the weld for the former filler wire but through the intermetallic compound layer for the latter one. A Zn-rich phase formed in the weld made with Zn-15% Al filler wire. Moreover, the Zn-Al filler wire also generated thick interfacial layer containing a great amount of intermetallic compounds and coarse dendrites in the weld, which led to a weak joint.     

工艺参数对激光透射焊接聚碳酸酯影响

利用激光透射焊接技术对聚碳酸酯（PC）塑料进行焊接,通过正交试验法研究了激光功率、焊接速度、碳黑含量对焊接强度和焊接质量的影响.探讨了热输入对焊接强度的影响,通过对焊缝显微形貌分析,进一步研究了炭黑含量对焊接质量的影响.结果表明,对PC材料来说,激光功率是首要影响因素,其次是焊接速度,最后是碳黑含量.最佳的焊接工艺参数为激光功率40 W,焊接速度40 mm/s,含碳量0.1%.热输入对焊接质量有较大影响,热输入在0.5～1.3 J/mm可得到较好强度的焊件.     

CO2含量对高强钢MAG焊焊缝金属低温韧性的影响

通过调节保护气体中CO2的含量,研究了保护气体氧化性对高强钢焊缝金属低温韧性的影响规律,同时分析了这种影响规律的作用过程。试验结果表明,随着保护气体中CO2含量增加,粒状贝氏体组织在焊缝金属中含量增加,焊缝金属低温韧性降低;当保护气体中CO2含量较少时,焊缝金属组织以针状铁素体为主,焊缝金属具有较高的韧性水平。     

High power laser welding of Nb microalloyed steel plates

Abstract

Laser welding studies on 12 mm thick Nb microalloyed steels were done using a 25 kW CO₂ laser at welding speeds of up to 3 m min^?1 with the aim of identifying the influences of Nb and carbon on laser weldability and weld properties. Welds were examined for solidification flaws, penetration characteristics, microstructure and mechanical properties. Solidification cracking did not appear to be influenced by carbon or Nb in the ranges studied when welding at power levels between 22 and 25 kW. The area fraction of martensite was shown to increase with decreasing energy input and increasing carbon content. Weld metal toughness was improved by reducing carbon content in the range 0·08–0·05%C but was little influenced by Nb. Weld metal and heat affected zone hardness levels were reduced, as expected, by reducing carbon content. The results show that increasing Nb content leads to higher strength material without significant loss of toughness, while lowering carbon content can improve toughness without loss of strength. Thus low carbon Nb microalloyed steels with about 0·05%C can achieve a good combination of parent plate and laser weld properties and appear to be suitable for high power laser welding situations.     

重要承载钢结构氢致裂纹影响因素分析

Q390低合金高强钢焊接时存在一定的冷裂倾向.对于具有较大拘束应力状态的Q390钢结构,需研究其熔敷金属氢致裂纹的影响因素,而氢致裂纹是由焊接过程中产生的扩散氢引起,故采用甘油法相对比较和分析了不同焊丝类型、不同环境湿度对Q390钢熔敷金属扩散氢含量的影响.结果表明,相同湿度下,实心焊丝熔敷金属扩散氢含量均明显小于药芯...     

影响45CrNiMoV高强度钢焊缝性能因素的探讨

本文用光学显微镜、扫描电镜和透射电镜研究了影响４５ＣｒＮｉＭｏＶ钢焊缝性能的因素。结果表明，焊丝成分、坡口形式和焊接工艺都直接影响焊缝的成分、组织结构，从而影响焊缝的性能。当焊缝具有回火板马氏体时，焊缝具有最佳的性能，当焊缝中出现上贝氏体时，焊缝的韧性下降。