Kind Of Welding Research Articles

Friction Welding Processes: A Review

Friction welding is a sort of solid-state welding process that does not use flux, shielding gases, or filler metal; instead, the heat needed to fuse the materials is produced by the friction between two or more objects moving relative to one another. This kind of welding is an alternative to the traditional fusion and adhesive-based welding procedures. The method is reliable, capable of joining materials that would seem hard to join with traditional welding, and suitable for joining both similar and dissimilar materials including wood, steel, aluminum, copper, masurium, nickel, zinc and carbon steel. Friction welding can be carried out by using several techniques including linear, rotary, friction stir, direct drive and inertia welding. Each of these welding techniques is distinct and are named according to the relative motion involved. Although the process varies slightly subject to the type of motion, the procedure is consistent and the resultant joint is comparable with those obtained through conventional welding technique. This study reviews the distinct friction welding processes and specific techniques involved in the process.

Study on magnetic memory detection of weld fatigue damage by using the relative entropy theory

In this paper, fatigue tests of different kinds of welds were carried out. The three magnetic components of MMM signal on the weld under different cycles were collected. The change law of MMM signal with the fatigue cycle was analyzed, and the relative entropy theory was introduced to establish the mapping relationship between the relative entropy and the fatigue cycle. The damage state of the weld was evaluated based on the change of the relative entropy. The results showed that the curves of initial MMM signal presented specific change law with the increase of fatigue cycle and a counter-trend change occurred at the local position after the weld failure. In addition, there was a good correspondence between the relative entropy with the fatigue stage of the weld. The value of relative entropy in the fatigue stable stage remained approximately constant and tended to be close to zero. In the final fatigue stage, the value of relative entropy increased exponentially. The relative entropy gradient and the magnetic index k were calculated to capture the time node of the deterioration of the weld more accurately and the k = 0.1 could be defined as the critical value to evaluated the stability of the weld. Hence, the relative entropy that was introduced could effectively characterize the fatigue damage degree of the weld, and realize the early warning of the weld damage.

Corrosion Behavior and Internal Pressure Capacity of a Composite System Used to Connect Metallic Pipes

This research aims over how different kinds of fiber-reinforced plastic (FRP) may change the internal pressure capacity and corrosion behavior of linked metal pipes. Hence, aluminum pipes have been fabricated for further usage in wrapping with various FRP and welding. Used FRP materials include carbon fiber/epoxy (CFRP) and kevlar fiber/epoxy (KFRP) (CFRP). These fibers have been slit into narrow strips for use in the fabric-winding technique of connecting. Four-layer KFRP pipes and eight-layer KFRP-CFRP pipes are also viable options that have been investigated. On the other hand, comparisons have been made using pipes that have two different kinds of welding. The findings demonstrated an increase in the internal pressure capacity of the pipe compared to welding. The corrosion test was finally performed. The findings demonstrated that FRP connecting methods outperformed both welded and unjoined pipes in terms of corrosion resistance. These findings indicate that FRP composites have a bright future for use in pipe joining.

Izbor postupka reparacije polomljene ruke jedne unikatne stolne lampe

Repair of any unicate artefact always requires the challenge and however demands for high level of knowledge & experience in this field, at the same level conservation works. Those demands are regarding not only on visual appearance, it is intended to stain unchainched other properties, even to question of strength, either it is an artistic piece, also the possibility of lowering the corrosion resistance, after the repair works have done. Here in details are analysed possible solutions for repairing of one broken arm when an unicate lamp unintentionaly is damaged. The used bulk material of the lamp is not available for using a kind of welding or soldering procedures, firstly that those methods will markably change the surface properties of the repaired zone. So, the repairing is provided by combining two methods: reinforcing with semi-hard aluminum wire and two component glue.

Development of friction stir powder embedding tool

From building bridges, erecting skyscrapers to fabricating automobiles metal joining allows engineers and manufacturers to realize metal structures. The method of joining metals remained mostly the same until 1991 when a new kind of welding was invented called Friction Stir Welding. This process through metal deformation instead of melting offers better results for welding of non-ferrous metals and their alloys. This study extends with the introduction of an indigenously tooling to powder embedding. This newly developed process can be applied beyond metal joining to surface processing. This study presents development iterations for the tooling used in friction stirred powder embedding.

Segregation in fusion weld of 2219 aluminum alloy and its influence on mechanical properties of weld

Three kinds of welds were made using low frequency pulse current variable polarity tungsten inter gas (LPVPTIG) with argon shielding, direct current TIG (DCTIG) with helium shielding and high frequency pulse current variable polarity TIG (HPVPTIG) with argon shielding, respectively. It was found that macrosegregation bands with large amount of thick continuous eutectics and microporosities formed in the LPVPTIG weld due to the fluctuation of the pulse varied heat input. Only microsegregation existed in the DCTIG weld and HPVPTIG weld. However, the HPVPTIG weld had lower extent of Cu microsegregation since its welding speed was slower. The tensile results indicated that the mechanical properties of the weld decreased with the increase of the segregation extent of Cu and porosities, and LPVPTIG weld had lower tensile properties in the longitudinal direction than those in the transverse direction due to the macrosegregation bands.

Influence of Aqueous Media on the Gas Saturation of Weld Metal in the Course of Underwater Welding of 12KH18N10T Steel

We estimate the potentials of hydrogenation and oxidation of aqueous media, the degree of gas saturation of the weld metal, and the mechanical properties of a welded joint obtained as a result of wet underwater welding with an experimental self-shielding wire. We study the influence of aqueous media on the physicochemical and metallurgical processes in the course of underwater arc welding. We also develop a complex of metallurgical and technological measures aimed at guaranteeing the high quality of joints formed by this kind of welding of 12Kh18N10T corrosion-resistant austenitic steel.

Simulation and experimental analysis of acoustic signal characteristics in laser welding

The characteristics of the acoustic signals generated in laser welding are investigated using a two-dimensional model, which was determined based on a theoretical investigation of the process heat balance. Three kinds of welds with different penetration depths induced by the welding parameters have been presented, and spherical field point meshes have also been built to obtain the spatial distributions of the acoustic radiation. The predicted oscillatory frequencies of the weld pools obtained by the modeling process are 1453.125, 1890.625, and 2750 Hz. To effectively isolate the environmental noise sources at the welding site, soundproofing equipment is designed that could reduce the acoustic pressure level of 10 dBA. Typical experiments using the soundproofing equipment are presented in the form of continuous wave Nd/YAG laser welding of an iron workpiece. Three weld shapes are obtained in the experiments at various welding speeds and the associated oscillatory frequencies are 1503.9, 1894.53, and 2792.96 Hz. The results show that the oscillatory frequencies of the weld pool that were predicted by the two-dimensional modeling process agree with the experimental results to within 4 %, which demonstrates the effectiveness of the proposed model for prediction of the acoustic radiation.

The influence of various factors on the geometric profile of laser lap welded T-joints

The effect of processing parameters, assembly parameters, and plate thickness on the weld bead geometry was examined, and the microstructure and microhardness of the typical joints were investigated in this paper. There are two kinds of welds, these are the Y-type and V-type welds in different heat input. Heat input has a small effect on bead width at the interface when the thickness of face plate is more than 3 mm. The variation of bead geometry is little when gap and offset size is small, while porosity or depression forms with increasing gap and offset. Plate thickness exerts a remarkable effect on the bead width at interface, and a big bead width at interface can be achieved by adopting thin face plate. The centricity of the laser beam is a big problem in laser lap welding T-joints with thin core plate, while bead width at interface is small in laser lap welding T-joints with thick face plate. Microstructure of heat-affected zone and fusion zone is composed of lath martensite and bainitic ferrite. Microhardness of fusion zone is lowest due to the coarse lath martensite. The desired bead geometry of laser lap welded T-joints can be produced by adopting low welding speed, thin face plate, and small gap.

Estimation of Grain Orientation in an Anisotropic Weld by Using a Model of Ultrasonic Propagation in an Inverse Scheme

The initial step towards a nondestructive technique that estimates grain orientation in an anisotropic weld is presented in this paper. The purpose is to aid future forward simulations of ultrasonic NDT of this kind of weld to achieve a better result. A forward model that consists of a weld model, a transmitter model, a receiver model, and a 2D ray tracing algorithm is introduced. An inversion based on a multiobjective genetic algorithm is also presented. Experiments are conducted for both P and SV waves in order to collect enough data used in the inversion. Calculation is conducted to fulfill the estimation with both the synthetic data and the experimental data. Concluding remarks are presented at the end of the paper.

An ultrasonic methodology to non-destructively estimate the grain orientation in an anisotropic weld

The initial step towards a non-destructive technique that estimates grain orientation in an anisotropic weld is presented in this paper. The purpose is to aid future forward simulations of ultrasonic NDT of this kind of weld to achieve a better result. A forward model that consists of a weld model, a transmitter model, a receiver model and a 2D ray tracing algorithm is introduced. An inversion based on a multi-objective genetic algorithm is also presented. Experiments are conducted for both P and SV waves in order to collect enough data used in the inversion. Calculation is conducted to fulfil the estimation with both the synthetic data and the experimental data. Concluding remarks are presented at the end of the paper.

Improvement of repair weld quality in low-alloy steel turbine casing components

Metal properties and residual stresses are studied experimentally in repair welds of steel 15Kh1M1FL casing components with use of a surfacing layer by UONI 13/55 and UONI 13/45 grade electrodes, and the permissible temperature range is evaluated for use of this kind of weld based on metal stress-rupture strength data.

Numerical study on mechanism of explosive welding

Explosive welding technology has been widely used in industrial production.However, there is always a controversy on the mechanism of explosive bonding,whether explosive welding should belong to a kind of mature welding such asa fusion welding or a solid phase welding. Based on the observation and analysisof the metallographs at interfaces, various opinions are proposed by differentauthors. This paper investigated the various mechanisms of the wavy interfaceformation in explosive welding and tried to determine a more reasonable oneby using smoothed particle hydrodynamics method. The numerical analysis resultsshow that explosive welding is a unique and complex kind of welding. In generalcases, high pressure and melted particles can be found in the collision areaat the interface. A version, in which explosive welding is a combination ofdiffusion bonding, fusion bonding and pressure welding, is considered as amore reasonable one.

A fracture mechanics approach to estimate the fatigue endurance of welded t‐joints including residual stress effects

ABSTRACTResidual stresses and weld defects play a major role in the fatigue behaviour of welded structures, so these effects need to be accounted for in a theoretical analysis. A simplified engineering procedure based on linear‐elastic fracture mechanics is applied to estimate the fatigue behaviour, particularly the limit of endurance. Local geometrical irregularities and pre‐existing flaws, which are typical for this kind of weld, are covered by an overall notch intensity factor instead of a specific stress intensity factor, so the initial flaw size is not needed explicitly in the analysis. The effect of residual stresses can be easily included. The cut‐compliance method was applied to measure the residual stress distribution on the cross‐section of the weld. A welded T‐joint was used as a benchmark. Unexpectedly, compressive residual stresses were found to prevail in the root region. According to the analysis, they contribute to the endurance limit of the considered joint by about 50%. This result was confirmed by fatigue tests where a significant decrease in the fatigue strength after a post‐weld stress relieving heat treatment was observed.

Relaxation of Residual Stress in AISI 347 Welded Pipe: A Time-of-Flight Neutron Diffraction Study

Abstract The residual stress state in an AISI 347 welded pipe for nuclear applications has been investigated by means of neutron time-of-flight diffraction. Two kinds of welds were compared: a ‘bare’ manual and a dressed tungsten inert gas (m-TIG with and without last pass heat sink, respectively). Thorough investigations along a line transverse to the weld seam and through-thickness have been carried out with very fine-step scans. Complementary microstructural investigations have been carried out by means of optical microscopy. Results show that the grain size varies from the parent material to the heat affected zone and weld pool. Some martensite is present in the parent material because of the cold working following each welding pass. In the weld pool, the heat flow seems to be redistributed effectively by the cap pass of the LPHSW. Although the microstructural heat affected zone is rather small, the effect of the weld on the stress state seems to extend further (the so-called strain affected zone). In...

Some Characteristics of Ultrasonic Welding of Polymers

Ultrasonic mechanical vibrations are usually introduced perpendicular to the welded surfaces, which coincides with the direction of the clamping force. The characteristics of the physical processes in ultrasonic welding (USW) of polymers cause heating of the parts to occur primarily at the site of their contact. For this reason, it is possible to form a high-quality weld at a lower temperature than with other kinds of welding. In some cases, USW of polymer parts is even possible at a temperature below their pour point (melting point), which allows obtaining welded articles made from different polymers and welding polymers whose degradation temperature is comparable to or lower than the melting point [fluoroplastic, poly(ethylene terephthalate)]. One of the most important characteristics of USW is the possibility of forming a high-quality weld at a relatively large distance from the site of introduction of mechanical energy, which allows obtaining sufficiently strong welded joint in articles of very complicated design. The possibility of manufacturing welded joints of polymers with contaminated surfaces significantly expands the range of application of USW, as it can be used for hermetic sealing of polymer containers filled with finished products. USW allows industrial production of nonwoven cloth both from purely thermoplastic polymer fibers and from blends with natural or other chemical fibers.

Ways to increase the reliability of welded joints of high-strength steels in a new generation of aircraft

A new generation of aircraft requires materials giving welded joints capable of operation under extreme conditions including the effect of various embrittling factors and active media in addition to static and cyclic loads. New steels have been developed and conventional steels have been modified with allowance for requirements on the base metal and the welded joints that would provide adaptability to different kinds of welding. The present work concerns the development of principles for alloying and optimizing the phase composition of added materials in welding high-strength steels for a new generation of aircraft. Corrosion-resistant steels and additives for parts operating under the effect of embrittling factors (cryogenic temperatures, temperature instability of the martensite matrix) and structural steels with elevated strength and reliability are considered.

Reaction of steel to heat cycles of welding

Figure i shows the distribution curves of the maximal heating temperatures and of hardness HVI0 in the heat-affected zone (HAZ) of the simulated welded joints with two kinds of welding. It can be seen that in the HAZ two unequal sections can be distinguished. The first section corresponds to Tma x = 15350-830~ and is characterized by hardness HVm ~3000 MPa; this is 50% more than the hardness of the base metal (with both kinds of welding),

Fusion Zone Cooling Curves for Deep Penetration Welds

Experimentally measured fusion-zone cooling curves are presented for a series of narrow, deep penetration welds. These are used to demonstrate that the conventional Rosenthal/Rykalin theory of moving heat sources can be used with considerable confidence for these kinds of welds provided that the width of the work-piece exceeds a certain minimum value. The results are discussed in terms of predicting weld microstructure.