scholarly journals Eliminating Delayed Cracks in Deep-Drawn SUS304 Cups Under Wider Range and Lower Magnitude of Blank Holding Forces Using Tin Coated Die

2021 ◽  
Author(s):  
Chin Joo Tan ◽  
Yoong Hau Phoo
Keyword(s):  
Deep Drawing ◽  
Room Temperature ◽  
Radial Flow ◽  
Lower Amount ◽  
Wall Thickening ◽  
Tin Coating ◽  
Die Surface ◽  
Strain Induced Martensite ◽  
Lower Magnitude ◽  
Commercial Lubricant

Abstract The effect of TiN coated die on eliminating delayed cracks in deep drawing processes of stainless steel SUS304 cylindrical cups under elevated blank holding forces (BHF) using a commercial lubricant at room temperature is investigated in the experiment. For comparison, the experiment is repeated using an uncoated and finely polished die under the same conditions. The results shows that the crack-free BHF range for the coated and the uncoated dies are 5~10 kN and 12 kN, respectively. Both the magnitude and range of the crack-free BHF are successfully lowered and enlarged by applying TiN coating to the die surface. Lower magnitude and wider range for BHF are preferred in the industries as it is difficult to maintain a high, constant and precise BHF during the deep drawing process using coil springs or die cushions. The elimination of the cracks is mainly due to the decrease in amount of strain-induced martensite resulting from the lower amount of wall thickening, particularly in the valley points along the cup earring profiles. The improved tribological performance by the coating enhances the radial flow of the materials into the die cavity resulting in lower amount of wall thickening. The chance for delayed cracks is reduced with decreasing amount of wall thcikening. Overall, the amount of tensile residual stresses along the outer surface of the cup, particularly in the upper portion is reduced with the coated die due to its low BHF. Therefore, the risk for the cracks is reduced.

scholarly journals Weakening affinity of SUS304 asperities to die surface with TiN coating for preventing delayed cracks in deep-drawn cups

2021 ◽  
Author(s):  
Chin Joo Tan ◽  
Yoong Hau Phoo
Keyword(s):  
Fe Simulation ◽  
Wall Thickening ◽  
Tin Coating ◽  
Strong Affinity ◽  
Drawing Die ◽  
Die Surface ◽  
The Reformation ◽  
Formation Of Cracks ◽  
Steel Surfaces ◽  
Coating Crack

Abstract SUS304 stainless steel has strong affinity to carbon tool steel surfaces. Therefore, the flow of material in the flange portion during the deep drawing process is retarded, leading to increase in amount of wall thicknening along the cup edge and rising risk for delayed cracks. In this paper, TiN coating is applied to the drawing die surface to weaken the affinity. Under elevated blank holding forces (BHF), the experimental results showed that the crack-free BHF range for the TiN coated and the uncoated dies are 5~10 kN and 12 kN, respectively. The entire BHF range for successful drawn cups formed with the coated die are crack-free. The crack-free BHF magnitude is successfully lowered and the range is enlarged with the coating. Crack-free cups having large elongated height and low amount of wall thickening along the cup edge are formed. The weak affinity is evidenced by the low estimated coefficient of friction (COF) obtained from a FE simulation model based on the Coulomb’s law of friction. In contrast, the estimated COF of the uncoated die is high even at the low BHF due to the strong affinity. Therefore, delayed cracks are observed under BHF range of 7~11 kN. At BHF of 12 kN, wear fragments are formed in the boundary layer as a result of the continuous polishing of the SUS304 asperities by the uncoated die asperities. The COF is sharpyly decreased due to the smooth relative movement of contacting surfaces facilitated by the particles and the formation of cracks is prevented. However, the segments tend to penetrate into the SUS304 surface under excessive BHF of 13kN and above. The relative motions of the segments are prohibited, resulting in the reformation of the cracks.

Formability and Process Conditions of Magnesium Alloy Sheets

2005 ◽  
Vol 488-489 ◽  
pp. 453-456 ◽  
Author(s):  
Shi Hong Zhang ◽  
Yong Chao Xu ◽  
G. Palumbo ◽  
S. Pinto ◽  
Luigi Tricarico ◽  
...  
Keyword(s):  
Deep Drawing ◽  
Tensile Tests ◽  
Process Conditions ◽  
Drawing Ratio ◽  
Temperature Range ◽  
Fine Grained ◽  
Axial Tensile ◽  
Die Surface ◽  
Lower Temperature Range ◽  
Lower Temperature

Comparing the formability with each other, extrusion and various rolling experiments were carried out to make fine-grained AZ31 Mg sheets, and uni-axial tensile tests were carried out at different strain rates and temperatures to investigate the effect of different variables. A warm deep drawing tool setup with heating elements, which were distributed under the die surface and inside the blank holder, was designed and manufactured, and deep drawing was performed. Extruded Mg alloy AZ31 sheets exhibit the best deep drawing ability when working in the temperature range 250-350°C. Extruded and rolled sheets of 0.8 mm thick were also deep drawn in the lower temperature range 105-170°C，showing good formability and reaching a Limit Drawing Ratio up to 2.6 at 170°C for rolled sheets. At last, a sheet cup 0.4 mm thick was deep drawn successfully at 170 °C.

Hydrogen Transport and Hydrogen-Assisted Cracking in SUS304 Stainless Steel During Deformation at Low Temperatures

2015 ◽  
Author(s):  
Lin Zhang ◽  
Bai An ◽  
Takashi Iijima ◽  
Chris San Marchi ◽  
Brian Somerday
Keyword(s):  
Stainless Steel ◽  
Hydrogen Embrittlement ◽  
Room Temperature ◽  
Hydrogen Release ◽  
Hydrogen Transport ◽  
Force Microscopy ◽  
Atomic Force ◽  
Strain Induced Martensite ◽  
Hydrogen Assisted Cracking ◽  
Slip Planes

The behaviors of hydrogen transport and hydrogen-assisted cracking in hydrogen-precharged SUS304 austenitic stainless steel sheets in a temperature range from 177 to 298 K are investigated by a combined tensile and hydrogen release experiment as well as magnetic force microscopy (MFM) based on atomic force microscopy (AFM). It is observed that the hydrogen embrittlement increases with decreasing temperature, reaches a maximum at around 218 K, and then decreases with further temperature decrease. The hydrogen release rate increases with increasing strain until fracture at room temperature but remains near zero level at and below 218 K except for some small distinct release peaks. The MFM observations reveal that fracture occurs at phase boundaries along slip planes at room temperature and twin boundaries at 218 K. The role of strain-induced martensite in the hydrogen transport and hydrogen embrittlement is discussed.

Investigation on Formability of AISI 304 Circular Cups by Warm Deep Drawing

2011 ◽  
Vol 418-420 ◽  
pp. 1410-1417
Author(s):  
N Ethiraj ◽  
V.S Senthil Kumar
Keyword(s):  
Sheet Metal Forming ◽  
Deep Drawing ◽  
Metal Forming ◽  
Draw Ratio ◽  
Room Temperature ◽  
Aisi 304 ◽  
Warm Working ◽  
Steel Aisi ◽  
Different Diameters ◽  
Stainless Steel Aisi

Deep drawing is one of the sheet metal forming processes used widely in industries like automobile, aerospace etc. In drawing operation, the limiting draw ratio (LDR) is used as an index of drawability of a material. In this investigation, stainless steel AISI 304 grade blanks of 1.0 mm thickness with different diameters are drawn into a circular cups in single stage. The experiments were conducted at room temperature as well as at temperatures 100oC, 200oC, and 300oC. The LDR values obtained in each condition were analyzed. The experimental results show that there is a significant improvement in LDR values by warm working.

Temperature and Processability of Magnesium Alloy AZ31 on Rectangular Cup Deep Drawing

2013 ◽  
Vol 535-536 ◽  
pp. 326-329 ◽  
Author(s):  
Yasuhide Nakayama ◽  
Tetsuo Naka ◽  
Takeshi Uemori ◽  
Ichiro Shimizu
Keyword(s):  
Magnesium Alloy ◽  
Numerical Simulations ◽  
Magnesium Alloys ◽  
Deep Drawing ◽  
Room Temperature ◽  
Local Heating ◽  
Plastic Strain Rate ◽  
Alloy Az31 ◽  
Magnesium Alloy Az31 ◽  
Plastic Forming

The magnesium alloys, that have high specific strength, are often applied to the industrial products. However, the magnesium alloys exhibit low ductility at the room temperature on account of its hexagonal close-packed structure. It is difficult to give large deformation to the magnesium alloys at room temperature. Therefore, the plastic forming of a magnesium alloy sheet needs the process at warm temperature. In the present work, the procedure of thermal-mechanical coupled analyses are employed. The numerical simulations of warm deep drawings have been performed in order to evaluate the dependence of the temperature on the plastic forming of a magnesium alloy AZ31 sheet. The mechanical properties of the magnesium alloy AZ31 shall be described as the functions depending on temperature. The shapes of punches and die holes are rectangle whose aspect ratios are 1.5 or 2.0. The corners of punches and dies are heated locally at 473K. The influence of local heating on the formability have been investigated. The relation between the blank size and the formability has been also estimated. As the results of numerical simulations, it was shown that the formability of deep drawing was improved by local heating to the punch and the die. When the blanks of various sizes were tried, the distributions of the plastic strain rate around the die corner were changed. Therefore, the deviation of the plastic flow and the temperature distribution arose in a sheet. Consequently, it is necessary to optimize the blank sizes according to the shape of die holes in addition to the forming temperature.

Application of Blank Optimization Method in Deep Drawing of Rectangular Magnesium Alloy Cups under Non-Isothermal Condition

2007 ◽  
Vol 344 ◽  
pp. 333-339
Author(s):  
W.T. Zheng ◽  
Donato Sorgente ◽  
G. Palumbo ◽  
Luigi Tricarico ◽  
Li Mei Ren ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Deep Drawing ◽  
Metal Forming ◽  
Room Temperature ◽  
Isothermal Condition ◽  
Optimization Methods ◽  
Optimization Method ◽  
Forming Process ◽  
Metal Forming Process ◽  
Blank Shape

Using the optimum blank in sheet metal forming process not only can decrease the material wasting but also avoid possible defects such as local severe thinning, wrinkling and fracture. Since it is practical technology for industrial production, many blank optimization methods have been proposed and their validity was verified by some forming tests of typical or complicated components. However, all the forming tests were carried out at room temperature or under isothermal condition. In present work, a blank optimization method was employed to evaluate its efficiency in deep drawing of rectangular magnesium alloy cups under non-isothermal condition. It is proved by experiment that the employed blank optimization method can predict successfully the optimum initial blank shape for the component with specified shape and dimension.

scholarly journals Room and High Temperature Tribological Performance of Multilayered TiSiN/TiN and TiSiN/TiN(Ag) Coatings Deposited by Sputtering

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1191
Author(s):  
Filipe Fernandes ◽  
Abbas AL-Rjoub ◽  
Diogo Cavaleiro ◽  
Tomas Polcar ◽  
Albano Cavaleiro
Keyword(s):  
Wear Debris ◽  
Room Temperature ◽  
Solid Lubricant ◽  
Wear Track ◽  
Tribological Performance ◽  
Tin Coating ◽  
Reduced Modulus ◽  
Adhesion Wear ◽  
Si Content ◽  
Better Than

In this study, we compare the tribological performance of a multilayer TiSiN/Ti(Ag)N coating with a TiSiN/TiN coating with a similar Si content in order to demonstrate the effect of the solid lubricant phase, silver. For Al2O3 balls, the hardness and reduced modulus determine the tribological performance of the coatings for tests conducted at room temperature (RT) against Al2O3 balls. At 550 °C, the TiSiN/TiN coating failed, whereas the Ag-containing coating performed better due to the presence of Ag in the contact, which decreased the shear stress and, consequently, the friction. For tests against TiAl6V4 balls, the Ag-containing coating was always better than the TiSiN/TiN one. At 550 °C, Ag in the wear track prevented the adhesion of the oxidized Ti-alloy wear debris in the contact, favoring the adhesion of wear debris from the coating to both the coating and counterpart surfaces. No wear could be measured for the 700 °C tests for both coatings due to different reasons: (i) the presence of oxidized adhered material from the ball to the reference TiSiN/TiN coating surface protected from wear and (ii) the presence of Ag-agglomerated particles decreased the friction and minimized the adhesion wear of the counterpart for the TiSiN/TiN(Ag) coating.

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