Kinds Of Filler Metals Research Articles

Wettability of GH4099 and MHC alloys by AgCuTi, TiZrCuTi and NiCrSiB filler metals and evaluation of diffusion-brazability

Abstract In order to investigate the diffusion bonding between Ni-based GH4099 alloy and Mo-based MHC alloy, the wettability of AgCuTi, TiZrCuTi and NiCrSiB filler metals on the surface of GH4099 alloy and MHC alloy was firstly performed. The results show that three kinds of filler metals have excellent wettability on the surface of two kinds of substrates, and are the suitable interlayers for joining GH4099 and MHC alloys. Secondly, diffusion bonding tests of GH4099 and MHC alloys were carried out by Gleeble thermally simulated experiments. The microstructures of three kinds of welding joints with different interlayers were compared and analyzed. It was found that Ti element had significant effects on improving the bonding strength of MHC side. A large number of Ni-Mo intermetallic compounds can easily be formed, which led to high brittleness of the joints. The experimental results showed that NiCrSiB is the best interlayer material for joining GH4099 and MHC alloys, and the shear strength of the joints can reach 116 MPa.

Effects of pure Ti or Zr powder on microstructure and mechanical properties of Ti6Al4V and Ti2AlNb joints brazed with TiZrCuNi

Ti6Al4V and Ti2AlNb alloys were brazed with three kinds of filler metals, typical commercial filler of TiZrCuNi, TiZrCuNi mixed with Ti or Zr powder. The microstructure evolution, production and growth mechanisms of reaction phases and mechanical properties of the brazing joints were investigated. The results demonstrated that primary dendrites formed by IMCs (Ti,Zr)2(Cu,Ni) and a layer of eutectic β+(Ti, Zr)2(Cu, Ni) products were observed in the TiZrCuNi joint. And the number of IMCs significantly in the joint increased when Zr powder was added in the filler. But if the addition was Ti powder, IMCs can be eliminated a lot. The suppression of ICMs production in the TiZrCuNi + Ti joint was mainly due to two reasons: firstly, the more β phase were firstly formed in the molten filler as the solid solubilities of Cu or Ni in Ti was higher than those in Zr; secondly, owing to the increased melting point of filler by adding the Ti powder, the time spent on the solidification of liquid filler can shorten and the segregation of Cu/Ni then partially repressed. Resulted from the efficient suppression of the detrimental IMCs, the highest tensile strength of 738.7 MPa was obtained by TiZrCuNi + Ti joint, which was higher than those of the TiZrCuNi joint (~136.1 MPa) and TiZrCuNi + Zr joint (~200.1 MPa).

The influences of different filler metals on the microstructure of Invar Fe-36Ni alloy multi-layer multi-pass MIG welding

The Invar Fe-36Ni alloy plates are welded by multi-layer multi-pass MIG welding with two kinds of filler metals in this paper. The microstructure of the joints is studied using scanning electron microscopy, x ray diffraction, and energy dispersive x-ray spectroscopy. And the morphology and microstructure of the joints with two different filler metals are compared. Moreover, the element distributions at different location are discussed. The results indicate that there are no pores or crack defects on the surface of the weld seam. The sizes of the incomplete fusion, which occurred in the interior of weld seam, using stainless steel filler metal are much larger than that of using Invar M93 filler metal. The distributions of elements in the interlayer are homogeneous using two filler metals. However, the element distributions, which are perpendicular to the fusion line, are not uniform using steel filler metal. The experimental results illustrate that the M93 Invar welding filler is better than stainless steel filler metal for multi-pass welding process of Invar Fe-36Ni alloy.

Microstructural evolution of SiC joints soldered using Zn–Al filler metals with the assistance of ultrasound

SiC ceramics were successfully soldered with the assistance of ultrasound. Two kinds of filler metals, namely non-eutectic Zn–5Al–3Cu and eutectic Zn–5Al alloys, were used. The effects of ultrasonic action on the microstructure and mechanical properties of the soldered joints were investigated. The results showed that ultrasound could promote the wetting and bonding between the SiC ceramic and filler metals within tens of seconds. For the Zn–5Al–3Cu solder, a fully grain-refined structure in the bond layer was obtained as the ultrasonic action time increased. This may lead to a substantial enhancement in the strength of the soldered joints. For the Zn–5Al solder, the shear strength of the soldered joints was only ∼102 MPa when the ultrasonic action time was shorter, and fractures occurred in the brittle lamellar eutectic phases in the center of the bond layer. With increasing ultrasonic action time, the lamellar eutectic phase in the bond layer of SiC joints could be completely transformed to a fine non-lamellar eutectic structure. Meanwhile, the grains in the bond layer were obviously refined. Those results led to the remarkable enhancement of the shear strength of the joints (∼138 MPa) using the Zn–5Al solder, which had approached that enhancement using the Zn–5Al–3Cu solder. The enhanced mechanical properties of the joints were attributed to the significant refinement of the grains and the change in the eutectic structure in the bond layer. Prolonged enhanced heterogeneous nucleation triggered by ultrasonic cavitation is the predominant refinement mechanism of the bond metals of the SiC joints.

Microstructure of diffusion-brazing repaired IN738LC superalloy with uneven surface defect gap width

ABSTRACTSlots with uneven width were cut by femtosecond laser in small plates of IN738LC superalloy to imitate service cracks. The ‘cracks’ were repaired by diffusion brazing using BNi-1a or a mixed filler alloy at 1100°C. The joint region was composed of isothermal solidification zone (ISZ), diffusion affected zone (DAZ) and precipitate zone (PZ). The compositions were different between the upper and lower ISZ due to the variation of gap width. The sample, repaired with two kinds of filler metals, had similar DAZ microstructure. PZ of mixed filler alloy bonded sample had a similar microstructure with that of BNi-1a, but less borides. The maximum gap sizes of complete isothermal solidification were almost the same for different filler alloys, followed a square root relationship with time. However, PZ of BNi-1a bonded was larger, resulting from a more base metal dissolution. The relationship between the PZ, ISZ and crack width is discussed.

Prevention of microcracking in dissimilar multipass welds of alloy 690 to type 316L stainless steel by Ce addition to filler metal

The microcracking susceptibility in dissimilar multipass weld metals was investigated by a multipass weld test using different type 316L stainless steels with varying P and S contents and using different alloy 690 filler metals with varying Ce contents. The relation between microcracking susceptibility and (P+S) and Ce contents in every weld pass of the multipass weld was investigated. Ductility dip cracks occurred in the compositional range of Ce/(P+S)<0·22, and solidification/liquation cracks occurred in that of Ce/(P+S)>1·1, while no cracks occurred at Ce/(P+S) between 0·22 and 1·1. The ductility dip cracking susceptibility could be improved by adding Ce due to scavenging of impurity elements. Microcracking could be completely prevented in dissimilar multipass weld metals using two kinds of filler metals containing 0·077 wt-%Ce for the weld passes beside the stainless steel base metal (320 ppm P and 183 ppm S) and containing 0·032 wt-%Ce for the other weld passes.

Low-Temperature Aging Characteristics of Type 316L Stainless Steel Welds: Dependence on Solidification Mode

Thermal aging embrittlement of light water reactor (LWR) components made of stainless steel cast has been recognized as a potential degradation issue, and careful attention has been paid to it. Although welds of austenitic stainless steels have γ-δ duplex microstructure, which is similar to that of the stainless steel cast, examination of the thermal aging characteristics of the stainless steel welds is very limited. In this investigation, two types of type 316L stainless steel weld metal with different solidification modes were prepared using two kinds of filler metals having tailored Ni equivalent and Cr equivalent. Differences between the two weld metals in the morphology of microstructure, in the composition of δ-ferrite, and in hardening behaviors with isothermal aging at 335 °C have been investigated. The hardness of the ferrite phase has increased with aging time, while the hardness of austenite phase has stayed the same. The mottled aspect has been observed in δ-ferrite of aged samples by transmission electron microscopy (TEM) observation. These characteristics suggest that spinodal decomposition has occurred in δ-ferrite by aging at 335 °C. The age-hardening rate of δ-ferrite was faster for the primary austenite solidification mode (AF mode) sample than the primary ferrite solidification mode (FA mode) sample in the initial stage of the aging up to 2000 hours. It has been suggested that the solidification mode can affect the kinetics of spinodal decomposition.

Microcracking susceptibility in dissimilar multipass welds of alloy 690 to type 316L stainless steel using La added filler metals

The microcracking susceptibility in dissimilar multipass welds of alloy 690 to type 316L stainless steel was investigated by the Varestraint test and the multipass welding test using the four different stainless steels varying the amounts of impurity elements such as P and S, and using the nine different filler metals of alloy 690 varying the La content. In order to simulate the dissimilar weld metals, stainless steels were gas tungsten arc (GTA) welded using alloy 690 filler metals with varying the dilution ratio. Microcracks occurring in the reheated weld metals were classified into ductility dip, liquation and solidification cracks. The ductility dip cracking susceptibility decreased with increasing the La content in the weld metal, while the liquation and solidification cracking susceptibilities increased contrarily when the La content in the weld metal exceeded ∼0·03 mass-%. The relation among the microcracking susceptibility, the (P + S) and La contents in every weld pass of the multipass welding was investigated. Ductility dip cracks occurred in the compositional range (atomic ratio) of La/(P + S)<0·17 and solidification/liquation cracks occurred in that of La/(P + S)>0·76, while any cracks did not occur at La/(P + S) being between 0·17–0·76. The ductility dip cracking susceptibility could be improved by adding La due to the scavenging of the impurity elements. The excessive La addition to the weld metal resulted in the solidification/liquation cracking alternatively attributed to the formation of Ni–La intermetallic compounds with low eutectic point. The optimal filler metal for the dissimilar multipass welding of alloy 690 to stainless steel was selected as La/(P + S) would be 0·17–0·76 for every weld pass. Microcracking could be completely prevented in the dissimilar multipass weld metal of alloy 690 to type 316L stainless steel by using two kinds of filler metals containing 0·03 mass-%La for the weld passes adjacent to the stainless steel base metal and containing 0·01 mass-%La for other weld passes.

Nd:YAG laser butt welding of AA6013 using silicon and magnesium containing filler powders

Aluminium alloy 6013 sheet was butt welded using a 3 kW Nd:YAG laser and different filler powders. Two kinds of filler metals were used: gas atomised powders of the aluminium alloys AlMg5, AlSi12, AlSi12Mg5 and AlSi10Mg, as well as mixtures of powders of the elements Al and Si and the binary alloys Al–5Mg, Al–5Zr, Al–5Cr and Al–10Mn. Microstructure, hardness, tensile properties and corrosion behaviour of the welds were investigated in the as-welded T4 and T6 conditions and after a post-weld heat treatment to the T6 temper. The weld region exhibited a dendritic cellular structure in the fusion zone and a partially melted zone adjacent to the fusion boundaries. The hardness of the fusion zone depended upon the filler metals used. Post-weld artificial aging to the T6 temper improved the hardness, being associated with precipitation of strengthening phases, as confirmed by transmission electron microscopy. Joint efficiencies achieved for post-weld heat treated joints ranged from 80 to 90%. Strengths of welds in the as-welded T6 condition were lower due to the softened fusion zone and heat affected zone, being between 70 and 75% of the ultimate tensile strength of the base alloy 6013–T6. Optimum tensile properties were obtained with joints made with the filler powder AlSi12. Reasonable tensile properties were achieved for welds made with mixtures of elemental and binary alloy powders, but they did not reach those of joints made with aluminium alloy powders. The dispersoid forming elements Zr, Cr and Mn added to a mixed Al–7Si powder did not prove beneficial effects on weld quality. When exposed to an intermittent acidified salt spray fog, joints in the as-welded T4 and post-weld heat treated T6 conditions exhibited corrosion behaviour similar to that of the base sheet in the tempers T4 and T6. As-welded 6013–T4 joints were susceptible to stress corrosion cracking when immersed in an aqueous solution of 0.6 M NaCl + 0.06 M NaHCO 3. Sensitivity to environmentally assisted cracking was associated with grain boundary precipitates in the heat affected zone.

各種ろう材による超音波併用アルミニウムのろう接 超音波併用アルミニウムのろう接 （第４報）

各種ろう材による超音波併用アルミニウムのろう接 超音波併用アルミニウムのろう接 （第４報）

硬ロウおよびロウ付接合部の衝撃強さ

As to impact-strength of brazed joints, there have been a few reports. They have not explained the relation between the impact strength of filler metals and that of the joints brazed with them, and also have not proved the state of fracture in brazed joint whose base metals as copper and copper alloys were weaker than filler metals.Authors investigated the relation between charpy impact-strength of filler metals and brazed joints using eight kinds of filler metals in Ag-P-Cu and Ag-Cu-Zn-Cd types and copper base metal. And we studied the fracture mechanism for various brazed joints, the effects of annealing for various filler metals and brazed joints and the influences of joint thickness in brazed joints for the impact strength.The test results summarized as follows :1) The impact-strength of filler metals in Ag-Cu-Zn-Cd type were stronger than that in Ag-P-Cu type and the impact-strength of both filler metals was improved by increase of silver contents in filler metals.2) The impact-strength of brazed copper joints was generally less than those of filler metals and it was determined by the impact-strength of filler metals.3) The fracture crack in impact specimens of brazed copper joints whose filler metals had higher impact-strength than base metal began from the boundary layer between filler metal and base metal. But, the fracture crack of brazed joints whose filler metals had less impact-strength than base metals began from filler metals. As a result, the absorbed energies in brazed joints had a large difference with both brazed joints.4) After diffusion annealing, impact-strength of brazing filler metals and brazed joints became weak in Ag-P-Cu type and strong in Ag-Cu-Zn-Cd type.5) When impact-strength of filler metals was higher than that of base metals, the thickness in brazed joints had no effect on impact-strength of brazed joints. But, when impact-strength of filler metals was weaker than that of base metals, the joint thickness gave some influences to impact-strength.