This paper discusses issues related to optimising the technological parameters of the process of brazing gold in a vacuum
furnace. An investigation of the brazing process was carried out for materials used in constructing components for aircraft engine
fuel systems. The vacuum brazed material was AMS 5510 stainless steel (in the form of plates and pipes). AMS 4787 (BAu-4) was
used as the brazing filler. In particular, the influence of the method of preparing the surface on solder spreading and the thickness
of the diffusion zone were analysed. The best spreading of solder was obtained for nickel plated surfaces. When the sample surface
was more rough or scratched, the effect of the spreading of solder was limited and the diffusion process of the solder into the base
material became dominant. Moreover, the influence of the brazing temperature on microstructure changes and on interdiffusion
of the AMS 5510 stainless steel/BAu-4 solder system was determined. It was observed that an increase in the brazing temperature
modifies the morphology of the formed joint by forming a massive and rounded phase. Furthermore, an increase in the brazing
temperature enhances the exchange of components.
The article summarizes the theoretical knowledge from the field of brazing of graphitic cast iron, especially by means of conventional
flame brazing using a filler metal based on CuZn (CuZn40SnSi – brass alloy). The experimental part of the thesis presents the results of
performance assessment of brazed joints on other than CuZn basis using silicone (CuSi3Mn1) or aluminium bronze (CuAl10Fe). TIG
electrical arc was used as a source of heat to melt these filler materials. The results show satisfactory brazed joints with a CuAl10Fe filler
metal, while pre-heating is not necessary, which favours this method greatly while repairing sizeable castings. The technological procedure
recommends the use of AC current with an increased frequency and a modified balance between positive and negative electric arc polarity
to focus the heat on a filler metal without melting the base material. The suitability of the joint is evaluated on the basis of visual
inspection, mechanic and metallographic testing.
Brazing of two dissimilar structural materials; Zircaloy-4 and SS-316L was performed at 900oC under high vacuum conditions. The metallic glass ribbons (Zr55Cu30Al10Ni2Fe3-at. %) of 30 µm thickness, were used as an interlayer. The bonded region was characterized by scanning electron microscope (SEM), energy dispersive spectroscope (EDS) and microhardness testing. The metallurgical bond formation was due to compositional changes in the molten interlayer and later on its subsequent solidification. Assessment of the bonded zone (BZ) revealed three distinct regions (Region-I, Region-II and Region-III). Diffusion transformation was observed in Region-I and Region-III which were interface with base alloys SS-316L and Zircaloy-4 respectively. However, Region-II at the middle of the BZ was composed of isothermally and athermally solidified portions. The highest values of Microhardness were observed in Region-III which was due to the presence of hard phases. Moreover, a crack parallel to BZ was observed in Region-III and was attributed to differential contraction of base alloys during cooling. Maximum shear stress acting on the BZ was calculated and correlated to the brittle phase cracking.
This paper outlines issues associated with gas-shielded braze welding of CU-ETP copper with austenitic steel X5CrNi18-10 (1.4301) using a consumable electrode. The possibilities for producing joints of this type using innovative low-energy welding methods are discussed. The paper provides an overview of the results of metallographic and mechanical (static shear test, microhardness) tests for braze welded joints made on an automated station using the Cold Metal Transfer (CMT) method. Significant differences in the structure and mechanical properties are indicated, resulting from the joint configuration and the type of shielding gas (argon, helium).
The article discusses tests concerning the assessment of the corrosion resistance, properties and the structure of TIG braze welded galvanised steel sheets. Test butt joints were made of 0.9 mm thick galvanised car body steel sheets DC04 (in accordance with EN 10130), using a robotic welding station and a CuSi3Mn1 braze (in accordance with PN-EN 13347:2003) wire having a diameter of 1.0 mm. The research-related tests aimed to optimise braze welding parameters and the width of the brazing gap. The test joints were subjected to visual tests, macro and microscopic metallographic tests, hardness measurements as well as tensile and bend tests. The corrosion resistance of the joints was identified using the galvanostatic method. The tests revealed that it is possible to obtain high quality joints made of galvanised car body steel sheets using the TIG braze welding process, the CuSi3Mn1 braze and a brazing gap, the width of which should be restricted within the range of 0.4 mm to 0.7 mm. In addition, the joints made using the aforesaid parameters are characterised by high mechanical properties. The minimum recommended heat input during process, indispensable for the obtainment of the appropriate spreadability of the weld deposit should be restricted within the range of 50 kJ/mm to 70 kJ/mm. At the same time, the aforesaid heat input ensures the minimum evaporation of zinc. Joints made using the TIG braze welding method are characterised by high resistance to electrochemical corrosion. The galvanostatic tests did not reveal any traces of corrosion in the joint area.
Thermal fatigue properties of WCu45/FeCr18Ni9 steel brazed joint with Ni-Cr-Si-B filler metal were investigated. Results indicated that the fatigue damage of Ni-based joint was aggravated with the increased of thermal fatigue cycles times. Moreover, the fatigue cracks appeared in the brazing seam and FeCr18Ni9 steel side near the brazing seam, and the bending strength of the brazed joint decreased from 333 MPa of original joint to 160 MPa of having experienced 200 thermal fatigue cycles. The fracture characteristic of Ni-based joint underwent 200 cycles was identified as mixed ductile-brittle fracture under the combined effect of external bending load and internal fatigue damage.