Susceptibility to Hot Cracking and Weldment Heat Treatment of Haynes 230 Superalloy

This study investigates the susceptibility of hot cracking and weldment heat treatment of Haynes 230 superalloy. The Varestriant test was conducted to evaluate this susceptibility. Welding was performed by gas tungsten arc welding （GTAW） and plasma arc welding （PAW） with stress relief heat treatment and solid solution heat treatment. A tensile test is then performed to measure the changes in the mechanical properties of the heattreated material. The results indicate that the number of thermal cycles does not affect the susceptibility of Haynes 230 superalloy to hot cracking. However, it does increase the strain. In weldment of heat treatment, stress relief annealing increases the yield strength and tensile strength of the welded parts. The section of the tensile specimens shows fibrous fractures on the welded parts, regardless of whether they are heat-treated.

Experimental study and optimization of cutting parameters in machining of super alloy with hybrid ultrasonic method

Super alloys are intensively used in various industries, especially in the aerospace industry, because of their special characteristics. A number of holes are sometimes required to be drilled into super alloys for aircraft at their final stage assembly. In the present study, a hybrid ultrasonic machining method, called rotary ultrasonic machining （RUM）, was successfully used in super alloy drilling. The empirical modeling of the process parameters of RUM was performed for the super alloy （Inconel 718） using an experimental design approach, called response surface methodology （RSM）. Parameters, namely tool rotation, feed rate, ultrasonic power, and abrasive grit size, were selected as input variables. The others were kept constant. The performance was measured in terms of the machining rate and the surface roughness. The developed models were found to be reliable representatives of the experimental results with prediction errors less than 4-5%. Moreover, the feed rate for the quality and productivity aspect was found to be the most critical factor. The optimized values of the machining rate and the surface roughness achieved through a multi-response optimization were 0.9 825 mm3/s and 0.951 i.tm, respectively.

Experimental and Numerical Research on Deformation Behavior of Thin-Walled and Large Expansion Ratio Guide Vane Liner in Hydroforming Process

Some tube hydroforming process tests and further research work were conducted to manufacture hollow guide vane liners( made of super alloy GH3030).The relative thickness( t0/ OD) of the tubular blank is approximately 0. 01,and the maximum expansion ratio( Dmax/ OD) of the needed part is more than 40%,and the length to diameter ratio of the expansion regionis more than 3. 0. It is very hard to manufacture this kind of ultra-thin-wall,curved axis and large expansion ratio tubular part without fracture and wrinkles. The success of the process is highly dependent on useful wrinkles with appropriate internal pressure and axial feeding. A simplified finite element model and a theoretical model are used for detecting the deformation behavior and forming laws. Further study results demonstrate that the useful wrinkles do not appear at the same time and middle-wrinkles need bigger axial force than tube-end-wrinkles and feeding-wrinkles. The wrinkles can transfer bigger axial force after its wave peak has come into contact with the die inner surface. The thickness thinning rate of the element at the peak is bigger than that at the trough. With the increase of the axial and hoop stress ratio,the critical buckling stress also increases. Microstructure examination results show that the grain size in the maximum thinning zone has been stretched and refined after the large deformation and annealing treatment.The process is feasible and the finished part is qualified.

Turning Affected Layers of GH4169 with Worn Tools

To solve problems of surface integrity of GH4169 caused by tool wear during machining,residual stresses layers(RSL),deformation layers(DL),and surface roughness of machined surface were studied in this work.Jobs were done at the turning parameters of v_(c)=15 m/min and f_(z)=0.05 mm/r and ap=1 mm with6 different worn tools.Firstly,tool nose wear closes to minor flank face and how it influenced machined surface were discussed.Details were given by image processing and it concluded to 5 tool w ear states according to cutting time.Secondly,relationships between tool wear states and tensile residual stresses(RS)were built so the RS range is manageable by placing a cutting time limit.Thirdly,affected layers’depths were associated w ith tool wear and the consistency betw een RSL and DL was presented.At last,roughness values variation with cutting time were discussed.Results show that RS in peripheral direction is far larger than that in axial direction.The total cutting time of a tool should be controlled within 37 min and a time period 30-37 min before severely worn owns excellent cutting effects.Tensile RS of 400 M Pa can be set as a reference value for evaluating tool quality from angle of workpiece.

Porosity,cracks,and mechanical properties of additively manufactured tooling alloys:a review

Additive manufacturing(AM)technologies are currently employed for the manufacturing of completely functional parts and have gained the attention of hightechnology industries such as the aerospace,automotive,and biomedical fields.This is mainly due to their advantages in terms of low material waste and high productivity,particularly owing to the flexibility in the geometries that can be generated.In the tooling industry,specifically the manufacturing of dies and molds,AM technologies enable the generation of complex shapes,internal cooling channels,the repair of damaged dies and molds,and an improved performance of dies and molds employing multipleAMmaterials.Inthepresentpaper,a reviewof AM processes and materials applied in the tooling industry for the generation of dies and molds is addressed.AM technologies used for tooling applications and the characteristics of the materials employed in this industry are first presented.In addition,the most relevant state-of-the-art approaches are analyzed with respect to the process parameters and microstructural and mechanical properties in the processing of high-performance tooling materials used in AM processes.Concretely,studies on the AM of ferrous(maraging steels and H13 steel alloy)and non-ferrous(stellite alloys and WC alloys)tooling alloys are also analyzed.