Investigation on Shearing and Local Formability of Hot-Rolled High-Strength Plates

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Liang Dong ◽  
Shuhui Li ◽  
Ji He ◽  
Ronggao Cui
Keyword(s):  
High Strength ◽  
Bending Test ◽  
Peak Hardness ◽  
Shear Surface ◽  
Forming Process ◽  
Junctional Zone ◽  
Microhardness Distribution ◽  
Sheared Edge ◽  
Edge Cracking ◽  
Hot Rolled

In order to evaluate the shearing quality, the material inhomogeneity through thickness after shearing is introduced by the authors. This study investigates the shearing and local formability of hot-rolled high-strength steel (HSS) plate, which is generally exploited for the manufacturing of the beam of heavy trucks. Various kinds of plates with different thicknesses and strengths are used to figure out the effect of material properties on the shearing quality. Both the shear surface morphology and microhardness distribution of the sheared edge are considered for evaluating the influence of the sheared-edge quality on local formability during the following forming process. Vickers hardness tests are conducted to analyze the microhardness distribution on the shear surface, which is proved to have significant effect on the local formability of the sheared edge. Furthermore, two kinds of bending tests and simulation are employed to study the edge cracking phenomenon, and the results indicate that the junctional zone of burnished zone and fracture zone, which is defined as peak hardness zone (PHZ), has a significant impact on major strain distribution on shear surface in the side bending test and this region is the main cause of edge cracking in normal bending test.

Effect of Variable Geometry on Springback of High Strength Steel Materials

2015 ◽  
Vol 1134 ◽  
pp. 154-159
Author(s):  
Muhamad Sani Buang ◽  
Shahrul Azam Abdullah ◽  
Juri Saedon ◽  
Yupiter H.P. Manurung ◽  
Mohd Shahir Mohd Hairuni ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
High Strength Steel ◽  
High Strength ◽  
Bending Test ◽  
Geometrical Parameters ◽  
Forming Process ◽  
Element Simulation ◽  
Punch Radius ◽  
Prevention Method

Springback is the phenomenon in which the material strip unbends itself after forming process. It is caused by the geometrical, mechanical properties or other process parameters. This paper focused on finite element simulation investigation on effects of geometrical parameters on the springback amount of the High Strength Steel (HSS). Two geometrical parameters, punch radius (Rp) and die opening (Wo) were selected and their effect on springback studied. Finite element simulation of U-bending test was performed using Simufact.formingTM with material database (MatILDa) and the level of the springback was measured. The result of the simulation shows that different values of punch radius (Rp) and die opening (Wo) are significant to the springback effect. 3 variable values of (Rp) and (Wo) selected in this studied are (2mm, 4mm, 6mm) and (30mm, 36mm, 48mm) respectively. The findings of the simulation could be used to accurately and reliably predict springback behavior of the tested material. The value of the springback increases, as the value of the die opening (Wo) increases. Meanwhile, the increasing value of the punch radius (Rp) will lead to decreasing springback value. From this finding, a proper prevention method can be taken to eliminate springback, achieve improvement in the forming process as well as reduce processing time and cost.

Robust Shearing Process for Improving AHSS Sheared Edge Stretchability

2012 ◽  
Author(s):  
Hua-Chu Shih ◽  
Ming F. Shi
Keyword(s):  
High Strength Steel ◽  
High Strength ◽  
Straight Edge ◽  
Edge Condition ◽  
Advanced High Strength Steel ◽  
Forming Process ◽  
Sheared Edge ◽  
Steel Grades ◽  
Edge Tension

Results from a previous study have shown that a newly developed beveled shearing process is able to improve the quality of advanced high strength steel (AHSS) sheared edges and their edge stretchability. The objective of the current study is to further investigate and validate this phenomenon and to develop robust shearing conditions for improving the AHSS sheared edge stretchability. A straight edge shearing device with the capability of adjusting the shearing variables is used in this study. Two different advanced high strength steel grades, DP600 and DP980, with similar thicknesses are selected to assess the edge condition using various shearing variables. The edge stretchability of the straight edge sheared specimen is evaluated using the sheared edge tension test and a half specimen dome test. It was discovered that an optimal selection of the die clearance and other shearing variables would result in a less damaged sheared edge which would greatly delay edge fracture in the forming process and increase the edge stretchability of AHSS.

Identification of Process-Based Limit Stress States Applying a Stretch-Bending-Test

2012 ◽  
Vol 504-506 ◽  
pp. 47-52
Author(s):  
Christian Hezler ◽  
Marion Merklein ◽  
Joachim Hecht ◽  
Bernd Griesbach
Keyword(s):  
High Strength ◽  
Bending Test ◽  
Forming Limit ◽  
Limit Curve ◽  
Forming Process ◽  
Forming Limit Curve ◽  
Distribution Diagram ◽  
Stress Limit ◽  
Stretch Bending ◽  
Strain Paths

The evaluation of forming simulation by using the forming limit curve has only limited validity if it is applied on car body components with non-linear strain paths. If modern high strength materials are used, the forming limit criteria can also provide invalid predictions. Especially high strength multiphase steels show a specific behaviour in forming, necking and crack initiation. If bending loads are applied to these materials, the onset of cracking occurs partially not within the range of the forming limit curve (FLC). The stress limit indicates the failure beginning more accurate. It is independent of the forming history and should be less sensitive to the behaviour of high strength steels. In the post processing of a simulation it could be used similar to the forming limit. A limit curve applied on the in-plane-stress-diagram of an analysed component defines areas that are more vulnerable for cracking. The required stress limit curve will be obtained in this research by applying a stretch-bending-test. It is selected in order to reach loads, which are comparable to the forming process in the components’ production. The forming state that is affecting the specimen is a combination of bending and stretching load. Different load conditions can be applied at the test by altering the stamp-radius and the specimen geometry. Since stresses cannot be measured directly in the experiment, the test is modelled in the simulation where the stresses can be calculated for a given material model. Finally the stress limit criterion was applied on the test parts’ stress distribution diagram. Occurring stresses above the stress limit curve are displayed on the simulation. Thereby it is possible to show a good correlation in critical areas between the failure prediction in the simulation and occurring rupture on the test component.

An Innovative Shearing Process for AHSS Edge Stretchability Improvements

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Hua-Chu Shih ◽  
Ming F. Shi
Keyword(s):  
High Strength Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Straight Edge ◽  
Forming Process ◽  
Expansion Test ◽  
Advanced High Strength Steels ◽  
Sheared Edge ◽  
Shear Edge

A beveled shear hole piercing process has recently been developed for advanced high strength steel (AHSS). The preliminary results have shown the new process is able to improve the quality of the sheared edge and the edge stretchability of AHSS. The goal of the current study is to optimize the beveled shearing process and identify the optimal shearing conditions for AHSS. Four different advanced high strength steels, including DP600, DP780, TRIP780, and DP980 with various thicknesses together with a conventional high strength steel, HSLA50, are selected in this study. The hole expansion test is used to evaluate the effect of shear edge conditions on the edge stretchability. The results show that an optimal selection of the die clearance and the shearing angle results in a less damaged edge, which significantly delays edge fracture in the forming process and increases the edge stretchability for AHSS. To further validate the advantages of the beveled shearing process in improving the shear edge quality of AHSS, a straight edge shearing device with the capability of adjusting the shearing variables (rake angles and die clearance) with respect to different sheet thicknesses was also developed and built. The edge stretchability of the straight edge sheared specimen was then evaluated using the sheared edge tension test. A similar trend to the beveled shear hole piercing process of AHSS is observed, and a significant improvement in the edge stretchability is also obtained with optimal shearing conditions.

scholarly journals An Infrared Local-Heat-Assisted Cold Stamping Process for Martensitic Steel and Application to an Auto Part

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1543
Author(s):  
Ki-Young Kim ◽  
Eun-Ho Lee ◽  
Soo-Hyun Park ◽  
Youn-Hee Kang ◽  
Jong-Youn Park ◽  
...  
Keyword(s):  
Present Method ◽  
High Strength ◽  
Local Heat ◽  
Industrial Applications ◽  
Bending Test ◽  
Forming Process ◽  
Stamping Process ◽  
Infrared Rays ◽  
Hot Press Forming ◽  
Cold Stamping

The automotive industry has tried to employ ultra-high-strength steel (UHSS), which has a higher strength with a thinner thickness. However, because of its low formability, there is a limit to the use of UHSS in industrial applications. Even though the hot-press-forming method can resolve the formability problem, elevated-temperature conditions lead to side effects—heat transfer and productivity issues. This work presents the concept of an infrared local-heat-assisted cold stamping process. Before the forming process, local areas, where the formability problem occurs, are locally heated by the gathering of infrared rays and cooled to room temperature before delivery. Since the heat treatment is completed by the material supplier, the stamping companies can conduct cold stamping without new investments or the productivity issue. In this work, a heat-assisted cold V-bending test was conducted with a martensitic (MS) 1.5 GPa steel, the CR1470M steel provided by POSCO. The heating effects on the microstructure, hardness, and local ductility were also observed. Finally, a commercial door impact beam was successfully manufactured with the present method. In this application, only a targeted small area was heated. The results show that the present method can improve the formability and springback problems of MS steel in the stamping process.

Deformation Characteristics of Advanced High Strength Steel under Cyclic Bending and Reversed Bending

2015 ◽  
Vol 651-653 ◽  
pp. 175-180
Author(s):  
Fuh Kuo Chen ◽  
Sin Liang Lin ◽  
Heng Kuang Tsai ◽  
Yi Wei Lin ◽  
I Kai Lin
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Metal Forming ◽  
Bauschinger Effect ◽  
High Strength ◽  
Bending Test ◽  
Forming Process ◽  
Element Analysis ◽  
Bending Tests ◽  
The Finite Element Analysis

In the present study, the Bauschinger effect exhibited in the advanced high strength steel under cyclic bending and reversed bending deformation was examined by both the experimental approach and the finite element analysis. The cyclic tension-compression tests were first conducted for the DP590 steel sheet to determine the material constants required in the Yoshida-Uemori model used in the finite element simulations. Since the deformation mode occurred in the reversed bending tests is similar to that presented in the sheet metal passing across the draw bead or die corner, a three-point reversed bending test apparatus was also developed and the experiments were conducted in the present study. The reversed bending test results clearly demonstrate that the Bauschinger effect presents in the reversed bending process. It confirms that the cyclic reversed bending tests can be applied to examine the Bauschinger effect exhibited in the sheet metal forming process. The finite element analysis was also performed to simulate both the U-hat bending and cyclic reversed bending processes. The comparison of the simulation results with the experimental data reveals that the finite element predictions in both springback and reversed bending load are more accurate if the Yoshida-Uemori model is adopted. It implies that consideration of the Bauschinger effect is necessary in the sheet metal forming if a reversed loading path is present during the forming process.

Study on the Deflection Behavior of HRBF RC Beams under Serviceability Limit States

2014 ◽  
Vol 638-640 ◽  
pp. 265-269
Author(s):  
Wen Jie Ge ◽  
Bi Yuan Wang ◽  
Da Fu Cao
Keyword(s):  
Bearing Capacity ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Capacity Utilization ◽  
High Strength ◽  
Bending Test ◽  
Limit States ◽  
Utilization Coefficient ◽  
Hot Rolled ◽  
Current Code

In order to investigate the deflection behavior of concrete beam reinforced with high strength hot rolled bars of fine grains (HRBF) under deflection control condition, four concrete beams reinforced with HRBF400 and HRBF500 rectangle cross-section concrete beam static bending test were made. The results show that Mid-span deflection of concrete beams reinforced with HRBF400 under normal conditions still meets the requirement of current code while concrete beams reinforced with HRBF500 could not meets the requirement. Mid-span deflection was calculated by current code and compared with experimental value, the results show that calculate value was a little bigger than experimental value and tend to be safe, deflection could still calculated by the current code. Bearing capacity calculates formula under the conditions of deflection control was proposed, conception of component’s bearing capacity utilization coefficient (BCUC) was put forward. Effects of reinforcement strength, concrete grade, reinforcement ratio and depth-span ratio on BCUC were analyzed.

Mechanical Properties and Component Behaviour of X80 Helical Seam Welded Large Diameter Pipes

2010 ◽  
Author(s):  
Franz Martin Knoop ◽  
Volker Flaxa ◽  
Steffen Zimmermann ◽  
Johannes Groß-Weege
Keyword(s):  
Mechanical Properties ◽  
Process Development ◽  
Large Diameter ◽  
Cold Deformation ◽  
High Strength ◽  
Forming Process ◽  
Fem Simulations ◽  
Bainitic Microstructure ◽  
Large Diameter Pipes ◽  
Hot Rolled

The paper discusses the development and processing of hot rolled X80 coil material and its conversion into thick-walled helical seam welded pipes. Microstructure, texture and mechanical properties of strips and pipes produced are characterized and compared. High strength characteristics and good deformability as a result of the fine homogenous mainly bainitic microstructure have been determined. Stress strain characteristics and the response to cold deformation during pipe forming have been investigated. Correlations between strip and pipe properties are described and have been used as a data basis for FEM simulations of the pipe forming process. The real pipe behavior has been investigated by means of burst tests performed on 48″ and 42″ pipe sections with 18.9mm wall thickness. The results achieved have been compared with results for other pipe grades, dimensions and types of pipe. An outlook will be given on future material and process development steps and use of X80 HSAW-pipes produced.

Methods to Decrease Cut Edge Sensitivity of High Strength Steels

2014 ◽  
Vol 611-612 ◽  
pp. 1294-1307 ◽  
Author(s):  
Thorsten Gläsner ◽  
Christina Sunderkötter ◽  
Armin Plath ◽  
Wolfram Volk ◽  
Hartmut Hoffmann ◽  
...  
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Cutting Process ◽  
Forming Process ◽  
Cold Forming ◽  
Cut Edge ◽  
Cutting Surface ◽  
Edge Sensitivity ◽  
Two Stages ◽  
Edge Cracking

The edge cracking sensitivity of AHSS and UHSS is quite challenging in the cold forming process. Expanding cut holes during flanging operations is rather common in automotive components. During these flanging operations the pierced hole is stretched that its diameter is increased. These flanging operations stretch material that has already been subjected to large amounts of plastic deformation, therefore forming problems may occur. An innovative cutting process decreases micro cracks in the cutting surface and facilitates the subsequent cold forming process. That cutting process consists of two stages, which produces close dimensional tolerance and smooth edges. As a result the hole expanding ratio was increased by nearly 100% when using thick high strength steels for suspension components

TENFORM XF450

Alloy Digest ◽  
2007 ◽  
Vol 56 (1) ◽  
Keyword(s):  
Physical Properties ◽  
Tensile Properties ◽  
Alloy Steel ◽  
High Strength ◽  
Bend Strength ◽  
Low Alloy Steel ◽  
Hot Rolled

Abstract The high strength of Tenform XF450, a hot-rolled high-strength low-alloy steel, allows the user to increase the strength of a finished component or to reduce the thickness. The steel is used in the construction and the automotive industries. This datasheet provides information on composition, physical properties, tensile properties. and bend strength. It also includes information on forming. Filing Code: CS-148. Producer or source: Hille & Mueller, USA Inc. See also Alloy Digest CS-173, November 2012.

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