Effects of CeF_3 on properties of self-shielded flux cored wire

Effects of CeF3 on properties of self-shielded flux cored wire including welding process, inclusions in weld metal and mechanical properties are systematically studied. Welding smoke and spatter are reduced with the addition of CeF3. The main non-metallic inclusions in weld metal are AlN and Al2O3. CeF3 can refine non-metallic inclusions and reduce the amount of large size inclusions, which is attributed to the inclusion floating behavior during the solidification of weld metal. The low temperature impact toughness is improved by adding suitable amount of CeF3 in the flux.

Effect of oxygen-containing additives on weld penetration in self-shielded flux cored arc welding

The effect of Fe203 and Liz CO3 additives in flux core on the weld metal oxygen content and weld penetration in self-shielded flux cored arc welding were studied schematically. The result shows that the oxygen content in the weld metal and weld penetration both increased with the Fe203 addition increased in the range of 5 wt. % to 20 wt. %. The oxygen content in the weld metal was increased with the Li2CO3 addition increased in the range of 1 wt. % to 8 wt. %. However, the weld penetration decreased when Li2CO3 addition exceeding 4 wt. %. High-speed photographic images show that when Fe2O3 addition influx core exceeding 15 wt. %, droplet became excessively large, so that spatters were frequently generated in large numbers. In this study, Fe203 and Li2 CO3 in the amount of 11 wt. % and 4 wt. %, respectively, jointly added in the flux core can achieve a deeper weld penetration with sound usability characteristics.

Investigation on mechanism of fixing nitrogen in self-shielded flux cored arc welding

Prevention of nitrogen porosity in weld metal deposited with self-shielded flux cored wire with CaF2-TiO2-MgO slag system can be accomplished by using a 'killing agent' such as titanium to react with nitrogen dissolved in the weld metal. The amount of titanium needed to prevent porosity is calculated thermodynamically for various dissolved nitrogen levels. Experimental flux cored wires are used to verify the thermodynamic model. It is concluded that approximately 0.11 wt% titanium in the weld deposit is need to prevent nitrogen porosity when welding without externally applied shielding.

STUDY ON METAL TRANSFER MODES OF SELF-SHIELDED FLUX-CORED WELDING WIRE

Metal transfer behavior of six kinds of self shielded flux cored wire(SSFCW) is studied using the apparatus of SSFCW high speed photography self made. Six kinds of metal transfer modes of SSFCW were obtained through observation for high speed photograph film and analysis. It is believed that the research is of magnificent for improving operative performance and mechanical properties of SSFCW and dynamics characteristic of welding power.

Formation Mechanism of Inclusion in Self-Shielded Flux Cored Arc Welds

The formation mechanism of inclusion in welds with different aluminum contents was determined based on thermodynamic equilibrium in self-shielded flux cored arc welds.Inclusions in welds were systematically studied by optical microscopy,scanning microscopy and image analyzer.The results show that the average size and the contamination rate of inclusions in low-aluminum weld are lower than those in high-aluminum weld.Highly faceted AlN inclusions with big size in the high-aluminum weld are more than those in low-aluminum weld.As a result,the low temperature impact toughness of low-aluminum weld is higher than that of high-aluminum weld.Finally,the thermodynamic analysis indicates that thermodynamic result agrees with the experimental data.

Predicting the composition of flux-cored wire claded metal by a neural network

In this paper, an artificial neural network method that can predict the chemical composition of deposited weld metal by CO 2 Shielded Flux Cored Wire Surfacing was studied. It is found that artificial neural network is a good approach on studying welding metallurgy processes that cannot be described by conventional mathematical methods. In the same time we explored a new way to study the no equilibrium welding metallurgy processes.

Investigation of the impact toughness of self- shielded flux- cored wire girth welds for X80 pipelines

Self-shielded flux-cored wire is a convenient and efficient consumable for pipeline field girth welding because of its self-protection characteristic and high deposition rate, especially for remote construction sites in rugged terrain. From the perspective of pipeline safety, the impact toughness of the girth welds is an important factor in pipeline integrity ,which determines the crack arrest behavior in the girth welds. Therefore, improving the girth weld impact toughness is of primary importance in the field of pipeline girth welding. Three self-shielded flux-cored wires comprising different chemical composition systems have been applied to large diameter X80 UOE （U-ing-O- ing-Expanding） pipeline semi-automatic girth welding,and the impact toughness of the welds has been evaluated by girth weld chemical composition analysis and microstructural analysis using scanning electron microscopy （SEM） and energy dispersive spectrometry （EDS） to investigate pipeline girth weld impact toughness and find ways to improve it. This helps in determining the main factors that influence girth weld impact toughness. Pipeline girth weld impact toughness is mainly determined by the final microstructure produced in the solid-state phase transition. In the as-weld state,acicular ferrite （AF） and fine bainite （FB） are a benefit to the impact toughness. For multilayer semiautomatic self-shielded flux-cored wire welding, the normalizing and tempering function of the latter beads to the initial beads plays an important role in the transition of girth weld microstructure, which affects the impact toughness. The original AF and FB and the corresponding heat treatment microstructure of the fine and uniform block ferrite and pearlite result in very good impact toughness. The following two mechanisms are found to promote the production of AF and FB in the girth weld. First, elements promoting the broadening of the austenitic region, such as Ni, C, Cu, and Mn, induce low temperature phase transitions and restrain the opposing function of Al, which is a benefit to the production of AF and FB. Second, dispersed high-melting-point inclusions, especially Al2O3 ,induce the nucleated production of AF. The advantageous function of inclusions is determined by their shape, distribution, and dimension. Dispersed spherical inclusions of small dimension are a benefit to the production of AF, and result in good impact toughness.

Effects of process parameters on the depth-to-width ratio of flux-cored wire underwater wet welding

The effects of process parameters on the depth-to-width ratio （D/W） of flux-cored wire underwater wet welding with a certain type of homemade .flux-cored wire are studied. It is found that the welding .speed, wire feeding speed and torch oscillating amplitude hare significant effects on the dopth-to-width ratio （D/W） of welds. The D/W ratio of welds increases significantly with the increase of welding speed without the oscillating of welding torch. It increased （from 0. 14 to 0. 26 ） with the increase of wire feeding speed while the torch oscillating. And it decreased linearly with the increase of torch oscillating amplitude. However, the influelwe of oscillating speed, wire extension and welding voltage on the D/W ratio of welds was not obvious.

STUDYONANEWKINDOFPOWDER－FEEDINGAPPARATUSOFFLUX－COREDWIREPRODUCTIONLINE

研制了一套药芯焊丝生产线电磁振动送粉机构及其单片机控制系统．通过对电磁振动送粉机构参数的测试，找到了送粉速度ＶＬ和电流Ｉ之间的数学表达式，使控制系统不仅可以根据带宽、药粉密度、轧丝速度和填充率自动计算出送粉量，而且可以根据轧丝速度调节送粉速度。

Droplet Transfer Behavior of Flux Cored Wire TIG Welding

This paper puts forward a new method to achieve flux cored wire TIG welding and uses high-speed photography to analyze the droplet transfer behavior and forces acting on the droplet. The droplet transfer forms include bridging transfer, slag column guided transfer, and non-contact transfer; each of these forms may be observed as the melting position of the welding wire changes. The important role of surface tension in the process of droplet transfer is proposed using static force balance theory and pinch instability theory. The phenomenon of droplet backward swing during welding process could be attributed to the vapor recoil force produced by vapors from the droplet. The welding experiments show that the proposed welding process is stable and that the weld quality produced is good.

STUDY ON FLUX-CORED WIRE FOR ELECTRIC ARC SPRAYING AND PROPERTIES OF COATING

According to the characteristics of electric arc spraying technology and abrasion of boiler piping,a flux cored wire SMD 45 for electric arc spraying is developed The experimental results show that the surface hardness of the coating reaches 60～65 HR and the adhesive strength between the coating and base is 23～28 MPa The wearability of the coating sprayed by the wire is 5 times than that of ordinary steel pipe Applying the wire to the heated surface,the life of the economizer pipe is doubly increased No local desquamation,rust and abrasion can be examined during more than one year's service.

Research on the abrasive wear resistance of YDCrMoV coating produced by CO_2 shielded flux-cored wire surfacing

Caterpillar construction machines play an important part in many fields such as hydraulic and electric engineering, the construction of highway, for its particular of structure. The walking system of caterpillar construction machines is always under the condition of three-body abrasive wear. The abrasive wear of walking system is very severe, which always results in damages of components or structures of walking system of caterpillar construction machines. It is very important to repair the walking system by cladding technique. The abrasive wear properties of four kinds coatings produced by the shielded flux-cored wire surfacing for the repair of the damaged components of walking system of caterpillar construction machines have been studied experimentally on an MLS-23 type wet sand rubber wheel abrasive tester. The surfaces morphologies of the abrasively worn specimens and their microstructures are investigated by transmitting electron microscopy (TEM) after wear testing. Results show that the wear mechanism of cladding metals of the flux-cored wire No.1 and the No.2 is micro-cutting while that of the No.3 and the No.4 is micro-ploughing. The four kinds of flux-cored wire coatings present great potential applications for the repairing of caterpillar construction machines in the Three Gorges Engineering.

钛型气保护药芯焊丝工艺质量影响因素综述

综述了涉及钛型气保护药芯焊丝工艺质量的影响因素。结果表明,合理选用药芯添加物,严格控制熔敷金属中主要强化元素C、Mn、Si的含量,可以改善焊丝熔滴过渡形态,获得焊丝熔敷金属满意的力学性能。在Ar+CO_(2)二元混合保护气体中,随着CO_(2)含量增大,熔滴过渡形态从轴向变为非轴向滴状排斥过渡,接头的抗拉强度几乎没有影响,但熔敷金属的冲击吸收能明显下降。热输入较大时,焊丝工艺性变差;热输入居中时,焊丝工艺性较好。热输入对焊丝熔敷金属韧性的影响出现了对热输入敏感和不敏感两种情况。钛型气保护药芯焊丝工艺质量的三个影响因素控制原理各具特色。

Q460NH耐候钢药芯焊丝焊接接头力学性能与组织研究

Q460NH是低合金高强度耐候钢,采用自制的CHT81W2药芯焊丝进行焊接,得到组织合理、力学性能良好的焊接接头。焊缝金相组织主要为先共析铁素体、板条铁素体、针状铁素体以及粒状贝氏体;热影响区组织主要有板条贝氏体和粒状贝氏体;焊缝、热影响区、母材的显微硬度呈梯度分布,并且依次下降。焊接接头各区的低温冲击韧性均达到标准规定的要求,具有良好的冲击性能;母材的断裂方式以延性断裂为主,断口微观形貌主要是韧窝;焊缝及热影响区的断口微观形貌为韧窝+准解理形貌。

药芯焊丝填充稳定性影响因素分析

以JL-YJQ5011药芯焊丝为例,对药芯焊丝填充稳定性影响因素进行分析。结果表明,药粉中金红石60目通过率100%,200目通过率≤15%,锰硅合金60目通过率100%,200目通过率≤40%,还原钛铁60目通过率100%,200目通过率≤20%,锆英砂80目通过率100%时,药粉的填充稳定性最好;金红石烘干到900℃左右,还原钛铁烘干到300℃左右,锰硅合金烘干到400℃左右,锆英砂烘干到800℃左右时,药粉的流动性最好;采用4连辊模拉拔,成90°交叉布置,4道次药粉受力方向成90°,双向变形,可以改善药粉流动性,解决药粉填充稳定性问题。

两种类型焊丝在桥梁角焊缝中的应用试验及工效分析

桥梁制造大量采用实芯焊丝焊接,与船厂习惯采用药芯焊丝不同,针对公司承接的桥梁单元制作工程,本文使用CO_(2)角焊小车,采用相同直径的实芯焊丝和药芯焊丝在不同的焊接参数、不同的焊接工件角度、不同的焊接工件坡口的工况下进行应用对比试验。通过焊接试验两种焊材的适用焊接参数、焊缝成型、焊接效率等数据,对比分析两种焊材焊接的应用差异和工效差异,并将结论应用于产品建造。

镍铜合金FCAW-G堆焊工艺研究

采用药芯焊丝气体保护焊(FCAW-G)对Q345R钢试板进行了镍铜合金N04400堆焊工艺评定,依照NB/T47014—2011《承压设备焊接工艺评定》要求对堆焊层的弯曲、化学成分及金相组织进行了检测。试验结果表明:采用80%Ar+20%CO_(2)混合保护气体,选用型号为ENiCu7T0-4的药芯焊丝进行过渡层及耐蚀层的堆焊,可以获得性能优良的耐蚀层,其化学成分满足标准要求,为镍铜合金实现高效堆焊提供了一种新的工艺参考。