Erichsen Cupping Test Research Articles

Differential speed rolling of Ni3Al based intermetallic alloy – Effect of applied processing on structure and mechanical properties anisotropy

Results of the first principles study on the effect of differential speed rolling (DSR) and a post-deformation annealing on a microstructure and microtexture evolution as well related mechanical properties anisotropy and formability of Ni3Al-based intermetallic alloy, have been shown in the present paper. Results of the EBSD structure analysis and mechanical properties evaluation indicate that the application of the proposed DSR process leads to a higher stored energy of deformation (and thus a higher strain hardening) than in the case of the conventional rolling process. Consequently, a subsequent post-deformation annealing results with a greater extend of the structure restoration processes than in the case of the normal cold rolling. The formability of the investigated intermetallic was evaluated by both a calculation of Lankford parameter (the r values) and Erichsen cupping tests. It is found that the susceptibility to deep drawing of the investigated Ni3Al intermetallic alloy is much lower than that of conventional deep drawn materials (e.g. aluminum alloys or low carbon steels). Nonetheless, the Ni3Al alloy exhibited a very low planar anisotropy and the yield strength anisotropy (and thus, a low tendency to strain localization upon drawing) independently on its structure state. This behavior should be mainly attributed to its simple phase composition (the lack of “a second phase” precipitation).

Determination of elastoplastic mechanical properties of the weld and heat affected zone metals in tailor-welded blanks by nanoindentation test

The elastoplastic mechanical properties of the weld and heat affected zone metals have comparatively major impact on the forming process of tailor-welded blanks. A few scholars investigated the elastoplastic mechanical properties of the weld and heat affected zone, but they only simply assumed that it was a uniform distribution elastoplastic material different from the base materials. Four types of tailor-welded blanks which consist of ST12 and 304 stainless steel plates are selected as the research objects, the elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals are obtained based on the nanoindentation tests, and the Erichsen cupping tests are conducted by combining numerical simulation with physical experiment. The nanoindentation tests results demonstrate that the elastoplastic mechanical properties of the weld and heat affected zone metals are not only different from the base materials, but also varying between the weld metals and the heat affected zone metals. Comparing the Erichsen cupping test resulted from numerical with that from experimental method, it is found that the numerical value of Erichsen cupping test which consider the elastoplastic mechanical properties of the weld and heat affected zone metals have a good agreement with the experimental result, and the relative error is only 4.8%. The proposed research provides good solutions for the inhomogeneous elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals, and improves the control performance of tailor-welded blanks forming accuracy.

초극박재 냉연코일의 연속조업을 위한 Laser Line Welder

Article history: A laser line welder using a solid-state laser (Yb:YAG) has been manufactured for joining ultra-thin cold-rolled steel coils in steelworks. The coils to be welded primarily range from 0.15 to 0.3 mm in thickness and 800 to 1,100 mm in width. Because the steel plate is extremely thin, it is very important to control the stop positions of the clamp at cutting and welding points. In this study, both hydraulic proportional control valves and LVDT sensor embedded cylinders were used to precisely control and monitor the positions of clamps with complementary stoppers. As a result, the positions could be controlled within an error of ±30 μm. Erichsen cupping tests on the welded joints show that the Erichsen index ranges from 4.4 to 4.6 mm. Furthermore, the tensile strength of welding points is comparable to that of the base metal.

Local Reversion of Cold Formed AISI 301LN

This study demonstrates applying laser heat treatment for reversion treatments of cold-formed AISI 301LN. Sheets were cold- rolled to final thicknesses of 1.5 and 3mm (65pct reduction), having martensite fraction of 70-95%. Sheets were heated locally by a laser beam to various peak temperatures to obtain different degrees of martensite reversion to austenite. Mechanical properties and formability of grain-refined and coarse-grained structures were measured by tensile, bending and Erichsen cup tests. In addition to standard Erichsen cup test, additional interrupted tests were carried out, where cups were first stretched close to the critical strain. Drawn cups were then heated locally by a laser beam to revitalize the structure and thereby enhance the formability in the following cupping test until failure.Various structures were produced: completely reverted microstructures (T > 700°C) with grain sizes 0.9 - 2μm in addition to partially reverted structure (T < 700°C) containing nano- and ultrafine-grained austenite (0.6μm) with some martensite. Results showed that local laser heat treatment is suitable for the reversion treatment to refine the austenite grain size. Refinement of the austenitic structures increased strength properties and the formability was better than with coarse grained structures having the same strength. Especially the yield strength was significantly enhanced, being around 900MPa in the strongest reverted structure compared to the 300-400MPa of the coarse grained austenitic structure. It was demonstrated that the local laser treatment restored formability of the drawn cups, allowing stretching to be continued.

Limiting drawing ratio and deep drawing behavior of dual phase steel tailor welded blanks: FE simulation and experimental validation

Strain localization and premature splitting in the vicinity of outer heat affected zone is a major concern in the formability performance of laser welded similar material dual phase (DP) steels during stretch forming. Hence, the present work aims at evaluation of limiting drawing ratio (LDR) of tailor welded blanks (TWBs) fabricated using two dissimilar material combinations of DP and interstitial free (IFHS) steels using laboratory scale deep drawing test. Finite element models of deep drawing of parent materials and TWBs were developed incorporating anisotropy of sheet metals and non-homogenous properties of the weld zone. The numerical simulations were performed incorporating theoretical forming limit diagram (FLD) to predict LDR, thinning development and failure location. The LDR of both the TWBs was lower compared to that of parent metals due to non-uniform plastic deformation with localized thinning failure at cup bottom in the weaker material side. The failure propagated along a direction parallel and close to weld line as observed in experimental results. The global forming performance of different TWBs was characterized and compared in terms of formability ratio from the deep drawing, limiting dome height and Erichsen cupping test data. It was found that the extent of decrease in formability due to increase in strength ratio was not so severe in deep drawing process unlike stretch forming process. It was also proposed through rigorous finite element studies that LDR of TWBs could be improved with restricted weld movement by shifting the initial weld line position, and the same was validated through deep drawing experiments.

Research on the Surface Topography Model of Galvanized Steels in Sheet Metal Forming

Due to the induced effect of plastic deformation and markedly influence of contact friction, the surface topography of galvanized steels has changed along with time and space during the sheet metal forming. WykoNT1100 non-contact optical profilometer was used to measure the surface topographies of different deformation zones in Erichsen cupping test. And the surface topography models of different deformation zones were established based on the statistical method. The results indicated that the surface topography was roughened with the increase of deformation and the degrees of roughening in different deformation zones were different. The function curve of micro-peak height in punch fillet zone which had serious deformation was relatively flat. It indicated that the data distributions were scattered, the roughness values were large and the zinc coating was severely exfoliated. However, the function curve in vertex zone was lanky with centralized data, small roughness values and intact zinc coating. Moreover, the surface topography was also affected by the contact friction.

Plastic Properties of Welds after Micro-Jet Cooling with Different Cooling Gases

New technology of micro-jet welding could be regarded as a new way to improve plastic properties of welds. The main purpose of that paper was analysing of plastic properties of welds made by MIG welding method with micro-jet cooling. The main reason of it was investigate possibilities of getting better plastic properties of welds made by MIG welding method with micro-jet cooling than plastic properties of welds made by ordinary welding method. It is possible for steel because higher amount of acicular ferrite (AF) in weld metal deposit (WMD) is obtained in MIG welding method with micro-jet cooling in relation to ordinary welding method (example: MIG welding method without micro-jet cooling). Moreover, it is possible to steering of weld structure and properties of the weld. During research Erichsen cupping tests and bending tests were carried out for welds made by MIG welding method with micro-jet cooling and ordinary welding method (MIG). Different kind of cooling gases were used to weld cooling. In this case comparison of plastic properties for different cooling gases was done. High amount of acicular ferrite influences positively on plastic properties. Higher values of plastic parameters were observed for welds made by MIG method with micro-jet cooling than for ordinary welding method. Different plastic properties were obtained for different cooling gases. In this research welds made by new method of welding (welding with micro-jet cooling) were compared witch welds made by ordinary welding method. New method of welding is very promising and capable of industrial application, mainly due to the significant improvement of weld properties and quality. That research was made only for steel welding with using MIG welding method. Another method of welding and another material were not tested. Other methods of welding have not been tested, but it is suspected that similar phenomena are taking place. Practical implications MIG method with micro-jet cooling it is way to get better plastic properties of welds in relation to welds made by ordinary welding method. It is very important because it could be used to steering of mechanical properties of welded constructions. This may have a positive impact on the parameters of the welding process (example: welding speed) and the quality of welded joints.

Sheet Metals Forming Die Design Using Finite Element Analysis and the Taguchi Method

Sheet metal deep-draw die is primarily constructed with draw bead, which is then modified based on trial and error to obtain a successful forming without splitting. This work aims at a robust design of forming die using numerical analysis and the Taguchi method. A three dimensional elastoplastic finite element model of a sheet metal forming process of SPCEN steel has been successfully developed using the material flow stress obtained from the modified Erichsen cup test. The model was validated with the actual forming experiment and the results agreed well. The influence of draw bead parameters on splitting and thinning distributions were examined using the Taguchi method. Four parameters, namely the friction coefficient, draw bead height, radius and shoulder radius were investigated. The Taguchi main effect analysis and ANOVA results show that the height and shoulder radius of the draw bead are the most important factor influencing the thinning distribution. Applying the Taguchi method and using the minimum thinning percentage as the design criteria, the optimum die design was identified as height, radius, shoulder radius and the friction coefficient of 4, 8, 8 mm and 0.125 respectively. The verified finite element model using the optimum die design was conducted. The predicted Taguchi response was within 5.9% from finite element analysis prediction. The improvement in the reduction of thinning percentage was 22.35%.

Investigations Into the Influence of Weld Zone on Formability of Fiber Laser-Welded Advanced High Strength Steel

In this study, two different dual phase steel grades DP980 and DP600, and IFHS steel sheets were laser welded by a 2-kW fiber laser. The weld quality of these three different LWBs was assessed with the help of microstructure, micro-hardness and transverse tensile tests. Tensile testing of longitudinal and miniature samples was performed to evaluate the mechanical properties of the weld zone. Formability of parent materials and LWBs were assessed in bi-axial stretch forming condition by Erichsen cupping test. To validate the weld zone properties, 3-D finite element models of Erichsen cupping test of LWBs was developed, and the failures in the deformed cups were predicted using two theoretical forming limit diagrams. It was observed that hardness of the fusion zone and HAZ in laser welded DP600 and IFHS steels was more compared to the respective parent metal. However, 29% reduction in hardness was observed at the outer HAZ of DP980 steel weldments due to tempering of martensite. Reduction of formability was observed for all the LWBs with two distinct failure patterns, and the maximum reduction in formability was observed in the case of DP980 LWBs. The presence of the soft zone is detrimental in forming of welded DP steels.

Influences of Thickness Ratio of Base Sheets on Formability of Tailor Welded Blanks

The influences of thickness ratio of base sheets on formability of tailor welded blanks were examined based on Erichsen cupping tests. Three-dimensional finite element (FE) models, using Hill’48 yield criterion and iso-hardening rule, were built under the environment of the FE analysis software ABAQUS. The failure onset sites of tailor welded blanks were analysed and the quantitative relationships between the Erichsen index values and base thickness ratio were established. Based on these relationships, the formability of tailor welded blanks made from dissimilar base sheets are evaluated, provided that the Erichsen index values of tailor welded blanks made from identical ones are known and that the above two different types of tailor welded blanks undergo a similar stamping process. The experiments were then carried out to validate this method.

Investigation of formability of CRCA Steel sheet by Erichsen Cupping Test analysis

The forming behaviour of cold rolled closed annealed steel sheet in Selected samples with proper annealing and chemical composition for better formability was investigated by Erichsen Cupping test method. The results showed that the formability of cold rolled closed annealed steel having lower percentage of carbon is lesser forming property and ductility. It was found that the stress distribution and the grain density of the sheet material confirm the formability. The best combination of strength and ductile properties has steel with the low carbon and better forming property.

Prediction of formability of laser-welded dual-phase steel by finite element analysis

Dual-phase steels are being applied in the automobile sectors for their higher strength with reasonable work hardening exponent. However, applications of these steels in tailor welded blanks for automobile part manufacturing involve laser welding and subsequent sheet forming. The thermal cycle during laser welding changes the local properties of the weld zone, which affects the formability. Hence, the present study was targeted to understand the effect of laser welding in formability of dual-phase steel. Laser welding of 1.2-mm-thick dual-phase steel with tensile strength of 600 MPa (DP600) and 980 MPa (DP980) was performed using 2-kW fibre laser set-up to fabricate two different laser welded blanks. The laser power and scan speed during welding were selected as 1.8 kW and 1000 mm/min, respectively. Weld quality was accessed using microhardness, metallography and transverse tensile tests. Formability of the laser welded blanks was evaluated in terms of cup height by Erichsen cupping test. It was observed that formability of welded blanks reduced compared to parent metals. The soft zone was observed in the heat-affected zone of DP980 welded specimens, and hence, reduction in formability was more. Finite element simulation of Erichsen cupping test was performed using LS-DYNA explicit finite element code.

Cryo-Rolling and Formability of 2024 Aluminium

Sheets of precipitate hardenable 2024 aluminium have been processed by rolling at liquid nitrogen temperature in order to refine the microstructure. A number of different aging/heat treating procedures have been utilised that have resulted in significantly different mechanical properties. The cryo-rolled material was heat treated at 150 °C for varying times and the resulting mechanical properties evaluated as a function of this holding time. The resulting properties were found to be strongly influenced by precipitates that formed either during the aging step, rolling process or the subsequent heat treatment. The formability of the cryo-rolled and heat treated material has been investigated using a limiting dome height test (Erichsen cupping test).

Comparative Study on Failure Prediction in Warm Forming Processes of Mg Alloy Sheet by the FEM and Ductile Fracture Criteria

An important concern in metal forming is whether the desired deformation can be accomplished without any failure of the material, even at elevated temperatures. This paper describes the utilization of ductile fracture criteria in conjunction with the finite element (FE) method for predicting the onset of fracture in warm metal working processes of magnesium alloy sheets. The uniaxial tensile tests of AZ31 alloy sheets with a thickness of 3 mm and FE simulations were performed to calculate the critical damage values for three kinds of ductile fracture criteria. The critical damage values for each criterion were expressed as the function of strain rate at various temperatures. In order to find out the best criterion for failure prediction, Erichsen cupping tests under isothermal conditions were carried out at various temperatures and punch velocities. Based on the plastic deformation histories obtained from FE analysis of the Erichsen cupping tests and the critical damage value curves, the initiation time and location of fracture were predicted under bi-axial tensile conditions. As a result, Cockcroft–Latham’s criterion showed good agreement with the experiments.

Enhancing Mechanical Properties and Formability of AISI 301LN Stainless Steel Sheet by Local Laser Heat Treatment

This study demonstrates applying local laser heat treatment to produce ultrafine-grained austenite (UFGA) structures in an AISI 301LN type commercial austenitic steel. Pieces of 50% cold-rolled sheets containing more than 90% strain-induced martensite were heated locally by a laser beam to various peak temperatures to obtain different degrees of martensite reversion to austenite. Mechanical properties and formability of grain-refined and coarse-grained structures were measured by tensile and Erichsen cup tests. In addition to standard Erichsen cup test, additional interrupted tests were carried out, where cups were first stretched close to the critical strain. Drawn cups were then heated locally by a laser beam to revitalize the structure and thereby enhance the formability in the following cupping test until failure. Results showed that local laser heat treatment is suitable for the reversion treatment to refine the austenite grain size. Various structures were produced: completely reverted microstructures (T &gt; 700 °C) with grain sizes 0.9 - 2 µm in addition to partially reverted structure (T &lt; 700 °C) containing nano- and ultrafine-grained austenite (0.6 µm) with some martensite. The grain refinement by local annealing improved the strength properties. The Erichsen cup tests showed that the formability was equal in the completely reverted ultrafine-grained structures to that of the coarse-grained sheets. It was demonstrated that the local laser treatment restored formability of the drawn cups, allowing stretching to be continued. The second forming step after the laser-treatment provided an enhancement of 19 and 14% in the cup depths in coarse-grained and ultrafine-grained steels, respectively, even though the laser-treatment parameters were not optimized yet.

Mechanical properties of ferritic stainless steel welds in using type 409 and 430 filler metals

In this study, feasibility of using typical ferritic filler metals (409LNb, 430LNb, and 430Ti) for welding of low and medium chromium ferritic stainless steels (EN 1.4003 and types 409, 430, and 441) was investigated. The paper concentrates on basic mechanical properties of gas metal arc-welded joints at ambient temperatures. A variety of mechanical testing, i.e., tension, microhardness, macrohardness, impact toughness, and Erichsen cupping tests, were carried out in order to clarify differences between the joints fabricated with these filler metals. Further, effects of postweld heat treatments on toughness and ductility were evaluated. Microstructures of the welds were analyzed using optical and scanning electron microscopy. According to the results, the tensile strength and ductility are acceptable, but the major limiting factor with these, as with other ferritic filler metals, is poor impact toughness in the weld region. Welds fabricated with the 430LNb welding wire had a ductile-to-brittle transition temperature (DBTT) above ambient temperature. The titanium-stabilized filler metal 430Ti can have improved impact toughness due to grain refinement. The poor impact toughness in the weld region is not seen in the formability of the weldments in Erichsen testing. Postweld heat treatments are beneficial only when welding the traditional type 430 steel. In fact, unnecessary postweld heat treatment runs the risk of decreasing the weldment toughness owing to Laves-phase embrittlement, particularly with type 441.

Impregnation of veneer with furfuryl alcohol for an improved plasticization and moulding

Due to mechanical restrictions veneer application on surfaces is limited to simple shapes. To enhance the moulding performance veneer samples were impregnated with furfuryl alcohol for improved plasticization. The plasticizing effect of furfuryl alcohol was determined according to the Erichsen cupping test and results were compared to control samples and water saturated samples. The extent of furfuryl alcohol plasticization is comparable to the use of water with the shaping path being distinctly improved by 71 % for water and 86 % for furfuryl alcohol. Little changes were observed for maximum load.

TWB 보론강의 기계적 특성 및 성형성

핫 스탬핑은 오스테나이트 변태 온도 이상에서 프레스 성형 후 급속히 냉각되는 고강도 부품을 제조하는 성형 방법이다. 매우 적은 양의 보론 성분을 가지고 있는 보론강은 핫 스탬핑에 사용되는 재료 중의 하나이다. 본 연구의 목적은 열처리 조건에 따르는 기계적 성질과 에릭슨 커핑 시험에 의하여 성형성을 조사하는 것이다. 다양한 온도에서 다이퀜칭은 대기 시간을 달리하여 실시하였다. 1173 K-0s에서 퀜칭 후 TWB는 1203 MPa의 인장 강도를 얻었다. 이것은 모재 인장강도(1,522 MPA)의 79 %이다. 금형 온도(298, 523, 673 K)에 따른 보론강 TWB의 성형성은 차이가 크지 않았다. 그러나 성형 속도가 증가함에 따라 성형성이 감소하는 것을 확인할 수 있었다.<BR>

Interface characterization and formability of two and three-layer composite sheets manufactured by roll bonding

Roll bonding is a solid-state welding process to join both similar and dissimilar metals and it is a well-established technique widely used in manufacturing processes. In this paper, the effect of rolling reduction, number of layers and the percentage of different amounts of SiC particles have been studied on the bond strength of the Al/SiCp laminated composites by lap–shear test and Erichsen cupping test. Furthermore, the interface region has been analyzed using micro-hardness test and metallographic observations. Rolling can give good bonds between metallic layers resulting in higher toughness of the product by refining the microstructure. Delamination of the interfaces is the main reason for the high impact and fracture resistance of the multilayer materials as well as increasing the extrinsic toughening by different mechanisms.

유한요소법과 연성파괴이론에 의한 AZ31합금 판재의 온간 드로잉 공정에서의 파단예측

Abstract The forming failure of AZ31 alloy sheet during deep drawing processes was predicted by the FEM and ductile fracture criteria. Uniaxial tensile tests of round-notched specimens and FE simulations were performed to calculate the critical damage values for three ductile fracture criteria. The critical damage values for each criterion were expressed as a function of strain rate at various temperatures. In order to determine the best criterion for failure prediction, Erichsen cupping test under isothermal conditions at 250℃ were conducted. Based on the plastic deformation histories obtained from the FE analysis of the Erichsen cupping tests and the critical damage value curves, the initiation time and location of fracture were predicted under bi-axial tension deformation. The results indicate that the Cockcroft-Latham criterion had good agreement with the experimental data. In addition, the FE analysis combined with the criterion was applied to another deep drawing process using an irregular shaped blank and these additional results were verified with experimental tests.