Materials Science Forum Vols. 539-543

Abstract: Dissimilar joining of Al alloys and steel was carried out using diffusion bonding process. The effects of Si and Mg contents of Al alloys and bonding parameters on the interfacial reaction were fundamentally investigated. While the reaction layers consisting of Fe-Al type intermetallic compounds (IMCs) formed at the interfacial region, in the joint with Al alloys including 1mass% Si or more a ternary Fe-Al-Si IMC layer formed at the Al alloy side. The growth of the reaction layers followed the parabolic growth low. A maximum joint strength was obtained at an average reaction layer thickness ranging from 0.5 to 1μm. The thicker reaction layer caused the fracture of the joints at a lower stress because of brittleness of the IMCs, and the thinner reaction layer including un-bonded interface also resulted in a low joint strength. As a result a thin and uniform reaction layer including less un-bonded interface can realize a high joint strength. Since the Fe-Al-Si IMC layer uniformly formed more rapidly than the binary Fe-Al IMCs in the joint with Al alloys including 1mass% Si or more, a higher joint strength was obtained at a thinner average reaction layer. As a result, it was found that the chemical compositions of 6000 series Al alloy controlled to be Mg (0.6 to 1.0mass%) and Si (more than 1.0mass%) were appropriate to obtain the better bonding characteristics.

Abstract: Dissimilar welded components joined with any kind of welding technologies gain an increasing interest due to significant improvements in engineering structures by using new materials (alloys) or new materials combinations. The present paper deals with laser welding of Al5083-H111 and Al6013-T6 and the characterization of the crystallographic texture. Fine grained Al5083 was joined with coarser grained Al6013.Whereas, Al6013 is strongly oriented dominated by a strong cube component and a much lower Goss component, the finer grained Al5083 shows a week deformation texture. The welding seam itself has a moderate cube texture with a minor <100> fiber texture in welding direction. A small texture variation about the texture strength and the volume fraction of the fiber component was observed along the weld. Results were obtained by neutron, hard X-ray and electron diffraction.

Abstract: Butt resistance welding of super duplex stainless steel type 329J4L with inserting type 316L stainless steel wires was investigated. When the base material temperature was increased from room temperature to 1373 K at the heating rate of 550 K /sec, base materials were jointed through the insert wires. HAZ (heat affected zone) of the joint interface were less than 80 μm. In this jointing technique, the insert wires played an important role of concentrating current on the wires and increasing their temperature up to melting point or near melting point. Thermal analysis using thermography revealed that insert wires were adequately heated just after current started at a load of 10 N. When the welding was performed at a load of 70 N, joint area was increased by plastic deformation of the base material. That led to decrease of current concentration. Consequently insert wires were jointed in the solid state.

Abstract: The effects of nitrogen content on weld metal impact toughness in submerged arc welding were investigated and interpreted in terms of microstructural changes and solid solution hardening. The weld metal impact toughness in as-welded condition decreased with increasing nitrogen content from 110 to 200 ppm. The weld metal microstructure changed with increasing nitrogen content; ferrite with second phase increased at the expense of tough acicular ferrite. In addition to microstructural changes, the microhardness of acicular ferrite increased gradually with the nitrogen content. Therefore, the loss of impact toughness can be attributed to a combination of the effects of microstructural changes and solid solution hardening.

Abstract: An integrated sensor method is used to measure interfacial temperature profiles with an ultrasonic friction test process. The profiles are compared to numerical results obtained by a transient thermal 2D axisymmetric finite elements (FE) analysis. In the experiments, the 50 $m diameter gold balls used in wire bonding are deformed by the capillary tool during impacting on the flat surface of a silicon chip (contact zone). The deformed balls then are pressed onto the SiO2 layer on the chip and vibrated with various amplitudes of 128 kHz ultrasonics. The 52 $m diameter contact zone is surrounded in 14 $m distance by a 50
aluminum resistor which is used as a resistive temperature detector. Temperature increases of typically 0.18 K and up to 0.3 K are measured by the sensor close to the heat source at the contact zone, corresponding to 3.1 K and 5.2 K at the interface as suggested by the FE model. With typical bonding parameters, the contact zone friction power is determined to be 4.4 mW which is less than 2 % of the electrical energy delivered to the used ultrasonic transducer type.

Abstract: When a voltage in the direction opposite to that for anodic bonding is applied to an anodically-bonded joint of glass whose alkali ion content is substituted by silver, silver precipitates of peculiar morphology form in the glass adjacent to the joint interface. In order to acquire knowledge about factors that control the configuration of the precipitates, effects of bonding time of the joints and application temperature of the reverse voltage on morphology of the precipitates were investigated. Shortening of the bonding time and increase of the application temperature of the reverse voltage cause decrease of the size of precipitates, and these effects were explained from formation frequency of current paths in the Ag+ depletion layer with penetration of Ag+ ions into the layer.

Abstract: The recent investigations about high strength manganese – nickel alloyed weld metals are reviewed. The mechanical properties from different alloying concepts and the associated microstructures are compared. Interesting similarities regarding the tensile and impact strength is noted, while large variations in microstructure is found.

Abstract: Weld modeling technology and control and mitigation techniques of residual stress and distortion have made a significant progress in the past decade. Q-Weld as the latest development in weld modeling technique can provide a solution in an extremely short time compared to a traditional thermo-elastic-plastic analysis. Three distortion control techniques, transient thermal tensioning, low stress non-distortion and in-process rolling, are discussed in this paper.