Effect of pulsed current micro plasma arc welding process parameters on fusion zone grain size and ultimate tensile strength of Inconel 625 sheets

The paper focuses on developing mathematical models to predict grain size and ul- timate tensile strength of pulsed current micro plasma arc welded Inconel 625 nickel alloy. Four factors, five levels, central composite rotatable design matrix is used to op- timize the number of experiments. The mathematical models have been developed by response surface method. The adequacy of the models is checked by analysis of vari- ance technique. By using the developed mathematical models, grain size and ultimate tensile strength of the joints can be predicted with 99% confidence level. Contour plots are drawn to study the interaction effect of pulsed current micro plasma arc welding parameters on fusion zone grain size and ultimate tensile strength of Inconel 625 weld joints.

Exclusive Jewelry Joits

There are shown the wide possibilities of combined micro plasma welding methods. They permit, for example, to do the local surfacing without essential deformations of rather thin jewelry elements, including a big growth a rise or layer of metal which exceeds it thickness in 2~8 times at the space with the approximately the same sizes. Such opportunities are based on the various possibilities of the joint producing-with different participation of metal parts and filler material. It may be added as a standard paste, wire, strip, etc. An operator can easy choose-where it is reasonable to apply only welding or brazing process as well as their combinations-due to his qualification, the concrete jewelry good design, needed accuracy of the given joint adjustment and, of course, the operators fantasy. At the same time he has excellentchances to repair the spoiled jewelry good or its element. All these processes are very easy for realization and theymay be even made by beginners and not only in jewelry, but also forrepairing of copper tubes, brass heat exchangers, various bronze goods, in dental purposes.

Thermal Contact Resistance between Aero Engine Compressor Blade and Flexible Fixture

In the process of two-pass micro plasma arc welding of titanium alloy sheet,based on the thermal contact resistance theory,a three-dimensional transient heat transfer finite element model of contact heat transfer between titanium alloy sheet and flexible fixture was established.The effects of contact upper surface temperature,micro-contact thermal resistance,micro-gap thermal resistance,DC and pulse welding on thermal contact resistance were investigated,and the simulation and experimental results were compared.The results show that the thermal contact resistance increases as the temperature increases when the temperature of the contact upper surface (titanium alloy sheet) is in the range of 290-350 K.The effect of micro-contact thermal resistance on the thermal contact resistance is 26.1%-46.3% larger than the micro-gap thermal resistance.The thermal contact resistance of pulse welding is 3.1%-3.5% larger than DC welding.The error of simulation and experimental results of weld pool depth is 8.6%,which verifies the reliability of the model.