Experimental Investigations on Development of Rapid Die Wear Tests for Stamping of Advanced High Strength Steels

2007 ◽  
Author(s):  
O¨mer Necati Cora ◽  
Yusuf Usta ◽  
Muammer Koc¸
Keyword(s):  
Low Cost ◽  
High Strength Steels ◽  
Wear Test ◽  
High Strength ◽  
Test Method ◽  
Experimental Investigations ◽  
Lightweight Materials ◽  
Die Wear ◽  
Wide Range ◽  
Aluminum And Magnesium Alloys

In a quest to achieve low-mass vehicles (i.e., higher fuel economy and lower emission), the automotive industry has been actively investigating the use of lightweight materials for a wide range of body panels and structural parts. Among the lightweight materials considered, Advanced and Ultra High Strength Steels (A/UHSS) hold promise as a prominent choice for the near future due to their relatively high formability and low cost compared to Aluminum and Magnesium alloys. However, due to their significantly higher strength than mild steel, in addition to the springback, blanking and joining issues, serious problems with the die wear are expected to arise during manufacturing. Although the die wear literature for the forming of conventional steels is prevalent, tribological issues of high strength steels have not been understood well yet. This study aims to develop a new, rapid and automated wear test for the die materials used in sheet metal forming operations of high strength steels (mainly DP and TRIP steels) and to investigate the wear, friction, and lubrication issues. With this test, the actual stamping conditions such as contact pressure, temperature, and sliding velocity can be represented well. Our preliminary tests on two different extreme contact conditions (soft-soft, hard-hard) indicate that this novel wear test method results in relatively reasonable wear rate estimations/measurements when compared to the results in the literature.

Investigations on the Effect of Coating Material and Method on Die Wear in Stamping of Advanced High Strength Steels

2013 ◽  
Author(s):  
Ömer Necati Cora ◽  
Muammer Koç ◽  
Peter J. Blau ◽  
Kunio Namiki
Keyword(s):  
Wear Behavior ◽  
High Strength Steels ◽  
High Strength ◽  
Test Method ◽  
Coating Materials ◽  
Advanced High Strength Steels ◽  
Die Wear ◽  
Die Life ◽  
Metalworking Industry ◽  
Width Measurements

Despite the advantages of advanced high strength steels (AHSS), their stamping into functional lightweight parts demands prolonged die life, which necessitates the use of alternative substrates, coating materials, and/or surface conditioning to minimize and delay the die wear. In order to avoid frequent die replacement and surface quality problems on the stamped parts, the metalworking industry has been investigating various approaches such as reducing/refining the carbide particles, adding alloying elements, and elevating the hardness and toughness values for both substrate materials and coatings. The objective of this work was to investigate the effects of different coatings on the wear behavior of a some selected tool steel materials (die sample of interest) against two different AHSS sheet blanks through a cylinder-on-flat type reciprocating test method. After wear tests, both die sample and sheet blank surface were microscopically examined. Wear resistance of the slider was quantified from wear scar width measurements. Results showed that TD and CVD coated die samples performed better than the two other PVD coated samples.

Automotive Materials: Technology Trends and Challenges in the 21st Century

MRS Bulletin ◽  
2006 ◽  
Vol 31 (4) ◽  
pp. 336-343 ◽  
Author(s):  
Alan I. Taub
Keyword(s):  
Smart Materials ◽  
High Strength Steels ◽  
High Strength ◽  
Research Society ◽  
General Motors ◽  
Lightweight Materials ◽  
Vehicle Efficiency ◽  
Materials Research ◽  
Energy Independence ◽  
Aluminum And Magnesium Alloys

AbstractThe following article is an edited transcript based on the plenary talk given by Alan I. Taub of General Motors Corp. on November 28, 2005, at the Materials Research Society Fall Meeting in Boston.Fuel economy requirements, emissions regulations, and the push for energy independence are key factors driving the auto industry to increase vehicle efficiency. The main avenues to efficiency improvement are powertrain enhancements and mass reduction. This presentation details how General Motors is developing advanced propulsion systems and using lightweight materials to achieve greater vehicle efficiency. Taub, who is executive director of General Motors Research and Development, outlines GM's strategy for advancing propulsion technology, from improvements in the internalcombustion engine to hybridization to full vehicle electrification. He then describes the company's efforts to use lightweight materials such as aluminum and magnesium alloys, high-strength steels, and composites to reduce vehicle weight. Also highlighted is GM's success in employing novel materials in the development of advanced vehicle and powertrain systems to achieve additional efficiencies. One example is the application of smart materials, which enable new features and functions by way of mechamatronic solutions (the integration of smart materials with mechanical systems and electronics). Key technical hurdles that must be overcome to increase the use of these materials by the automotive industry are also discussed.

Investigations on the Mechanical Properties and Formability of Friction Stir Welded Tailored Blanks

2007 ◽  
Vol 344 ◽  
pp. 143-150 ◽  
Author(s):  
Gianluca Buffa ◽  
Livan Fratini ◽  
Marion Merklein ◽  
Detlev Staud
Keyword(s):  
Mechanical Properties ◽  
Stress Condition ◽  
Research Effort ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Friction Stir ◽  
Tailored Blanks ◽  
Sheet Stamping ◽  
Wide Range

Tight competition characterizing automotive industries in the last decades has determined a strong research effort aimed to improve utilized processes and materials in sheet stamping. As far as the latter are regarded light weight alloys, high strength steels and tailored blanks have been increasingly utilized with the aim to reduce parts weight and fuel consumptions. In the paper the mechanical properties and formability of tailored welded blanks made of a precipitation hardenable aluminum alloy but with different sheet thicknesses, have been investigated: both laser welding and friction stir welding have been developed to obtain the tailored blanks. For both welding operations a wide range of the thickness ratios has been considered. The formability of the obtained blanks has been characterized through tensile tests and cup deep drawing tests, in order to show the formability in dependency of the stress condition; what is more mechanical and metallurgical investigations have been made on the welded joints.

Third generation of advanced high-strength steels: Processing routes and properties

2016 ◽  
Vol 233 (2) ◽  
pp. 209-238 ◽  
Author(s):  
Tarun Nanda ◽  
Vishal Singh ◽  
Virender Singh ◽  
Arnab Chakraborty ◽  
Sandeep Sharma
Keyword(s):  
Automobile Industry ◽  
Second Generation ◽  
Low Cost ◽  
High Strength Steels ◽  
High Strength ◽  
Cost Effective ◽  
Processing Route ◽  
Third Generation ◽  
Specific Strength ◽  
Advanced High Strength Steels

The automobile industry is presently focusing on processing of advanced steels with superior strength–ductility combination and lesser weight as compared to conventional high-strength steels. Advanced high-strength steels are a new class of materials to meet the need of high specific strength while maintaining the high formability required for processing, and that too at reasonably low cost. First and second generation of advanced high-strength steels suffered from some limitations. First generation had high strength but low formability while second generation possessed both strength and ductility but was not cost effective. Amongst the different types of advanced high-strength steels grades, dual-phase steels, transformation-induced plasticity steels, and complex phase steels are considered as very good options for being extended into third generation advanced high-strength steels. The present review presents the various processing routes for these grades developed and discussed by different authors. A novel processing route known as quenching and partitioning route is also discussed. The review also discusses the resulting microstructures and mechanical properties achieved under various processing conditions. Finally, the key findings with regards to further research required for the processing of advanced high-strength steels of third generation have been discussed.

Evolution of Hydroforming Technologies and Its Applications — A Review

2020 ◽  
Vol 19 (04) ◽  
pp. 737-780
Author(s):  
P. Venkateshwar Reddy ◽  
B. Veerabhadra Reddy ◽  
P. Janaki Ramulu
Keyword(s):  
Tube Hydroforming ◽  
High Strength Steels ◽  
High Strength ◽  
Lightweight Materials ◽  
Hydroforming Process ◽  
Rapid Pace ◽  
Innovative Work ◽  
Ultra High Strength Steels ◽  
Different Characteristics ◽  
Forming Methods

Advanced forming technologies have been evolving at a rapid pace with the products applicability in the industrial fields of aerospace and automobile especially for the materials like aluminum and titanium alloys (light weight) and ultra-high strength steels. Innovative forming methods like hydroforming (tube and sheet) have been proposed for industries throughout the world. The ever-increasing needs of the automotive industry have made hydroforming technology an impetus one for the development and innovations. In this paper, the review on various developments towards lightweight materials for different applications is presented. The influencing process parameters considering the different characteristics of the tube and sheet hydroforming process have also been presented. General ideas and mechanical improvements in sheet and tube hydroforming are given late innovative work exercises. This review will help researchers and industrialists about the history, state of the art in hydroforming technologies of the lightweight materials.

Frictional Behaviors of a Mild Steel and a TRIP780 Steel Under a Wide Range of Contact Stress and Sliding Speed

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Chongmin Kim ◽  
Jeong-Uk Lee ◽  
F. Barlat ◽  
Myoung-Gyu Lee
Keyword(s):  
Mild Steel ◽  
Contact Pressure ◽  
High Strength Steels ◽  
Diffraction Method ◽  
High Strength ◽  
Contact Stresses ◽  
Minor Amount ◽  
Sliding Speed ◽  
Normal Contact ◽  
Wide Range

The application of advanced high-strength steels (AHSS) generally makes it necessary to use higher tool-sheet contact pressures compared with those used for forming low-strength steel, and it leads to significant changes in frictional behavior, which in turn change the final product characteristics. In order to understand frictional behaviors between steel sheets and tool materials under high contact stresses present in real stamping conditions, a novel friction tester was conceived, fabricated, and used. This tester can generate high normal loads, as high as 625 MPa, whereas traditional friction testers were limited to 10 MPa or less. A mild steel and a TRIP780 steel were paired with Cr-coated D2 tool steel, and friction behaviors were observed under various conditions, including the use of two lubricants, wide ranges of sliding speeds, and normal contact stresses. The coefficient of friction (COF) decreased at a low contact pressure as the sliding velocity increased. The contact pressure had a significant effect, albeit too complex to be explained by simple models. It was also evident that lubricant effects must be studied coupled with the contact pressure and sliding speed. In a nonlubricated condition at normal stresses roughly half of the steel’s yield strength, the friction event caused plastic deformation that reached up to 0.2 mm from the surface. In this deformed region, the amount of retained austenite in the TRIP steel decreased substantially, and significant residual compressive stress, reaching 350 MPa, also developed in the ferrite phase (plus a minor amount of martensite, which is undistinguishable from ferrite by the X-ray diffraction method used herein). The magnitude of change of friction constant due to changes in contact conditions was enough to significantly affect springback of automotive body panels.

Effect of Strain Paths on Formability Evaluation of TRIP Steels

2010 ◽  
Vol 89-91 ◽  
pp. 214-219 ◽  
Author(s):  
David Gutiérrez ◽  
A. Lara ◽  
Daniel Casellas ◽  
Jose Manuel Prado
Keyword(s):  
Strain Path ◽  
High Strength Steels ◽  
High Strength ◽  
Test Method ◽  
Forming Limit ◽  
Trip Steels ◽  
Advanced High Strength Steels ◽  
Strain Paths ◽  
Analysis System

The Forming Limit Diagrams (FLD) are widely used in the formability analysis of sheet metal to determine the maximum strain, which gives the Forming Limit Curve (FLC). It is well known that these curves depend on the strain path during forming and hence on the test method used to calculate them. In this paper, different stretching tests such as the Nakajima and the Marciniak tests were performed, with different sample geometries to obtain points in different areas of the FLD. An optical analysis system was used, which allows following the strain path during the test. The increasing use of advanced high-strength steels (AHSS) has created an interest in determining the mechanical properties of these materials. In this work, FLCs for a TRIP steel were determined using Nakajima and Marciniak tests, which revealed different strain paths depending on the type of test. Determination of the FLCs was carried out following the mathematical calculations indicated in the ISO 12004 standard and was also compared with an alternative mathematical method, which showed different FLCs. Finally, the tests were verified by comparing the strain paths of the Nakajima and Marciniak tests with a well-known mild steel.

Experimental Investigations on Wear Resistance Characteristics of Alternative Die Materials for Stamping of Advanced High Strength Steels (AHSS)

2008 ◽  
Author(s):  
O¨mer Necati Cora ◽  
Muammer Koc¸
Keyword(s):  
Wear Resistance ◽  
Surface Hardness ◽  
High Strength Steels ◽  
High Strength ◽  
Wear Testing ◽  
Experimental Investigations ◽  
Advanced High Strength Steels ◽  
Automotive Body ◽  
Die Materials ◽  
Aisi D2

Newer sheet alloys (such as Al, Mg, and advanced high strength steels) are considered for automotive body panels and structural parts to achieve lightweight construction. However, in addition to issues with their limited formability and high springback, tribological conditions due to increased surface hardness and higher work hardening effect necessitate the use of improved alternative die materials, coatings, lubricants to minimize the wear-related issues in stamping of such lightweight materials. This study aims to investigate and compare the wear performances of seven (7) different die materials (AISI D2, Vanadis 4, Vancron 40, K340 ISODUR, Caldie, Carmo, 0050A) using a newly developed wear testing method and device. We used DP600 sheets in the tests. Our results showed that almost all of the recently developed specially-alloyed die materials demonstrated higher wear resistance performance when compared with the performance of AISI D2 die material.

Finite Element Simulation of Chain-Die Forming U Profiles with Variable Cross-Section

2017 ◽  
Vol 898 ◽  
pp. 1177-1182 ◽  
Author(s):  
Y.G. Li ◽  
Y. Sun ◽  
H.L. Huang ◽  
D.Y. Li ◽  
S.C. Ding
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Low Cost ◽  
High Strength Steels ◽  
High Strength ◽  
Variable Cross Section ◽  
Roll Forming ◽  
Variable Cross ◽  
Advanced High Strength Steels ◽  
Die Forming

Roll forming has been widely used to manufacture constant cross-section products because of high quality, efficiency and low cost. It is quite epidemic in producing automobile parts made of advanced high strength steels (AHSS) nowadays. However, with the development of the vehicle industry and diversity of the products, variable cross-section profiles have attracted more and more attention. The traditional roll forming technique is difficult to meet the requirements. Chain-die forming which was introduced in recent years makes it possible. Chain-die forming is an extension of roll forming and its key characteristic is enlarging the rotation radii of the moulds, by which the deformation zone is extended. The study focused on the finite element simulations of Chain-die forming U profiles with variable cross-section, including variable width and height. The feasibility of Chain-die forming producing variable cross-section products was verified by the perfect simulation results. The advantage of Chain-die forming was that there was no need to design the intermediate moulds except the finished-profile ones, which reduced the mould quantity immensely. Then the cost was lower.

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