Influence of Vibration Frequency on Residual Stress Reduction of Die Casting Mold

2017 ◽  
Vol 2017.23 (0) ◽  
pp. 1208
Author(s):  
Hiromasa ANAHARA ◽  
Masashi KUROSE
Keyword(s):  
Residual Stress ◽  
Stress Reduction ◽  
Vibration Frequency ◽  
Die Casting ◽  
Casting Mold

Relationship Between Forced Vibration Method and Residual Stress in Die Materials

2020 ◽  
Vol 14 (5) ◽  
pp. 824-834
Author(s):  
Masashi Kurose ◽  
Hiromasa Anahara ◽  
Takeshi Tane ◽  
Yoshihide Kuwabara ◽  
Kenta Aoshima ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Reduction ◽  
Forced Vibration ◽  
Stress Measurement ◽  
Die Casting ◽  
Tensile Residual Stress ◽  
Cavity Surface ◽  
Repeated Heating ◽  
Die Materials

During aluminum die-casting, tensile residual stress accumulates on the cavity surface of the die by repeated heating and cooling processes. Recently, to improve productivity, dies with high cycle and longer life have become necessary, and reduction or removal of tensile residual stress can be used to prevent heat cracks that cause mold fracture. Heat treatment is often used for residual stress reduction but a more efficient residual stress reduction method that can be carried out with simpler equipment is required. In this study, the relationship between the residual stress after forced vibration and the amplitude at the time of excitation is investigated by mechanical vibration of the SKD61 die materials and the die-casting mold through the application of forced vibration by an eccentric motor. Residual stress on the surface of each test plate treated by the heat treatment and the surface of mold cavity after excitation is evaluated by the X-ray residual stress measurement. It was found that the residual strain after excitation accumulated in compression as the amplitude of oscillation of the specimen became negative. Residual stress in the excitation direction of the specimens increased in the compression direction due to the excitation, demonstrating the effective stress reduction by the excitation method.

scholarly journals Optimization Study of Post-Weld Heat Treatment for 12Cr1MoV Pipe Welded Joint

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 127
Author(s):  
Zichen Liu ◽  
Xiaodong Hu ◽  
Zhiwei Yang ◽  
Bin Yang ◽  
Jingkai Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Reduction ◽  
Simulation Method ◽  
Post Weld Heat Treatment ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Tempering Treatment ◽  
Temper Heat Treatment ◽  
Weld Heat

In order to clarify the role of different post-weld heat treatment processes in the manufacturing process, welding tests, post-weld heat treatment tests, and finite element analysis (FEA) are carried out for 12C1MoV steel pipes. The simulated temperature field and residual stress field agree well with the measured results, which indicates that the simulation method is available. The influence of post-weld heat treatment process parameters on residual stress reduction results is further analyzed. It is found that the post weld dehydrogenation treatment could not release residual stress obviously. However, the residual stress can be relieved by 65% with tempering treatment. The stress relief effect of “post weld dehydrogenation treatment + temper heat treatment” is same with that of “temper heat treatment”. The higher the temperature, the greater the residual stress reduction, when the peak temperature is at 650–750 °C, especially for the stress concentration area. The longer holding time has no obvious positive effect on the reduction of residual stress.

In Situ Thin Film Stress Measurements – A Path to Understanding the Structure and Morphology of Electron Beam Evaporated ZnS

2002 ◽  
Vol 749 ◽  
Author(s):  
Vincent Barrioz ◽  
Stuart J. C. Irvine ◽  
D. Paul
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Electron Beam ◽  
Stress Reduction ◽  
Float Glass ◽  
Film Stress ◽  
Intrinsic Stress ◽  
Ex Situ ◽  
Stress Measurements

ABSTRACTZnS is a material of choice in the optical coating industry for its optical properties and broad transparency range. One of the drawbacks of ZnS is that it develops high compressive intrinsic stress resulting in large residual stress in the deposited layer. This paper concentrates on the evolution of residual stress reduction in ZnS single layers, depending upon their deposition rate or the substrate temperature during deposition (i.e. 22 °C and 133 °C). The substrate preparation is addressed for consideration of layer adhesion. Residual stress of up to − 550 MPa has been observed in amorphous/poor polycrystalline ZnS layers, deposited on CMX and Float glass type substrates, by electron beam evaporation at 22 °C, with a surface roughness between 0.4 and 0.8 nm. At 133 °C, the layer had a surface roughness of 1 nm, the residual stress in the layer decreased to − 150 MPa, developing a wurtzite structure with a (002) preferred orientation. In situ stress measurements, using a novel optical approach with a laser-fibre system, were carried out to identify the various sources of stress. A description of this novel in situ stress monitor and its advantages are outlined. The residual stress values were supported by two ex situ stress techniques. The surface morphology analysis of the ZnS layers was carried out using an atomic force microscope (AFM), and showed that stress reduced layers actually gave rougher surfaces.

scholarly journals Effect of Process Parameters and High-Temperature Preheating on Residual Stress and Relative Density of Ti6Al4V Processed by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 930 ◽  
Author(s):  
Martin Malý ◽  
Christian Höller ◽  
Mateusz Skalon ◽  
Benjamin Meier ◽  
Daniel Koutný ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Residual Stresses ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Stress Reduction ◽  
Laser Melting ◽  
Preheating Temperature ◽  
Laser Velocity

The aim of this study is to observe the effect of process parameters on residual stresses and relative density of Ti6Al4V samples produced by Selective Laser Melting. The investigated parameters were hatch laser power, hatch laser velocity, border laser velocity, high-temperature preheating and time delay. Residual stresses were evaluated by the bridge curvature method and relative density by the optical method. The effect of the observed process parameters was estimated by the design of experiment and surface response methods. It was found that for an effective residual stress reduction, the high preheating temperature was the most significant parameter. High preheating temperature also increased the relative density but caused changes in the chemical composition of Ti6Al4V unmelted powder. Chemical analysis proved that after one build job with high preheating temperature, oxygen and hydrogen content exceeded the ASTM B348 limits for Grade 5 titanium.

Computer Simulation of Filling Process and Temperature Distribution of Oil Pump Cover in Solidification Process

2013 ◽  
Vol 423-426 ◽  
pp. 1894-1897
Author(s):  
Han Wu Liu ◽  
Lian Dong Huang ◽  
Shun Qin Fan ◽  
Bo Hu
Keyword(s):  
Wall Thickness ◽  
Thermal Equilibrium ◽  
Cooling System ◽  
Die Casting ◽  
Solidification Process ◽  
Equilibrium Temperature ◽  
Forming Process ◽  
Element Analysis ◽  
Casting Mold ◽  
Oil Pump

Oil pump cover, as a part of the oil pump, is generally formed by adopting aluminum die casting molding, and required for good internal and external quality. In order to improve the oil pump cover forming quality, the paper first simulates the thermal equilibrium of die-casting mold in the forming process by finite element analysis, and obtains the temperature curves when mold works for 10 consecutive cycles, and determines that the thermal equilibrium temperature of die-casting mold is 260 °C. And then, based on the simulation results of filling and solidification in the forming process by ProCAST software, the shrinkage and cavity appear in the larger wall thickness of the casting. Meanwhile, by simulating the die-casting processes of the oil pump at different pouring temperatures, there are the least of shrinkage and cavity when the pouring temperature setting 640 °C. The results show that: it can take some methods to achieve the progressive solidification, and can reduce or eliminate the possible shrinkage and cavity, such as shortening the distance between sprue, runner and inner runner and die casting to reduce the casting heat loss, or adding cooling system to accelerate the cooling rate in the larger wall thickness of the casting. This analysis provides theoretical basis for the actual casting production of oil pump covers.

Stress Reduction of Amorphous Silicon Deposited by PECVD

2016 ◽  
Vol 1812 ◽  
pp. 109-116
Author(s):  
César B. Pérez ◽  
C. Reyes-Betanzo
Keyword(s):  
Residual Stress ◽  
Amorphous Silicon ◽  
Thermal Annealing ◽  
Stress Reduction ◽  
Microfluidic Devices ◽  
Wet Etching ◽  
Glass Substrates ◽  
Deposition Power ◽  
Si Films ◽  
Deposition Conditions

ABSTRACTAmorphous silicon (α-Si) was deposited on glass substrates by PECVD at different deposition conditions in order to characterize the residual stress on the film. Subsequently, a thermal-annealing was applied for different times at 400 °C in a N2 atmosphere, aiming to reduce the stress in the films. The deposition power was between 15 and 30 W at 13.56 MHz, the pressure in the chamber was adjusted in a range from 600 to 900 mTorr, and the temperature was varied from 140 to 200 °C. The stress was determined by using the Stoney equation, measuring the curvature and thickness of the α-Si films with a stylus profilometer. A deposition rate between 7-24 nm/min was obtained, and the time for thermal-annealing needed to reduce the stress was reduced from 10 to 2-4 h, obtaining a minimum compressive stress of 17 MPa. With this value of stress, it was possible to use the α-Si as masking material for wet etching of glass during the manufacturing of microfluidic devices, in order to obtain microstructures in the glass with 150 μm in depth.

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