Friction and Die Wear in Stamping Prephospated Advanced High Strength Steels

2016 ◽  
Vol 9 (2) ◽  
pp. 481-487 ◽  
Author(s):  
Hua-Chu Shih
Author(s):  
Ömer Necati Cora ◽  
Muammer Koç ◽  
Peter J. Blau ◽  
Kunio Namiki

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.


Author(s):  
Hua-Chu Shih ◽  
Ming F. Shi

Advanced high strength steels (AHSS) have been widely used in vehicle structural components due to their high strength nature with balanced formability. In a typical application, a zinc coating is often required and applied to AHSS for the purpose of corrosion protection. Due to the high strength nature of AHSS, higher forming forces and binder pressures are also required in stamping AHSS, which often results in coating galling and die wear. The degree of coating galling and die wear depends upon forming process variables such as contact pressure, forming speed, lubrication and die temperatures. In this study, the Bending Under Tension (BUT) tester was used to evaluate the effects of these process variables on coating galling and die wear. Dual phase (DP) 590 and 780 steels with galvanized (GI) and galvannealed (GA) coatings were investigated in the study. The results indicate that GI coatings tend to have better wear resistance than GA coatings. A better surface treated (Thermo-Reactive Diffusion Vanadium Carbide) die material was also identified to decrease coating galling and die wear in stamping AHSS.


2021 ◽  
Vol 182 ◽  
pp. 106687
Author(s):  
Yu Xia ◽  
Chu Ding ◽  
Zhanjie Li ◽  
Benjamin W. Schafer ◽  
Hannah B. Blum

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1136
Author(s):  
Marcel Carpio ◽  
Jessica Calvo ◽  
Omar García ◽  
Juan Pablo Pedraza ◽  
José María Cabrera

Designing a new family of advanced high-strength steels (AHSSs) to develop automotive parts that cover early industry needs is the aim of many investigations. One of the candidates in the 3rd family of AHSS are the quenching and partitioning (QP) steels. These steels display an excellent relationship between strength and formability, making them able to fulfill the requirements of safety, while reducing automobile weight to enhance the performance during service. The main attribute of QP steels is the TRIP effect that retained austenite possesses, which allows a significant energy absorption during deformation. The present study is focused on evaluating some process parameters, especially the partitioning temperature, in the microstructures and mechanical properties attained during a QP process. An experimental steel (0.2C-3.5Mn-1.5Si (wt%)) was selected and heated according to the theoretical optimum quenching temperature. For this purpose, heat treatments in a quenching dilatometry and further microstructural and mechanical characterization were carried out by SEM, XRD, EBSD, and hardness and tensile tests, respectively. The samples showed a significant increment in the retained austenite at an increasing partitioning temperature, but with strong penalization on the final ductility due to the large amount of fresh martensite obtained as well.


2004 ◽  
Vol 101 (7-8) ◽  
pp. 551-558 ◽  
Author(s):  
R. Bode ◽  
M. Meurer ◽  
T. W. Schaumann ◽  
W. Warnecke

Author(s):  
Mohammad Mehdi Kasaei ◽  
Marta C Oliveira

This work presents a new understanding on the deformation mechanics involved in the Nakajima test, which is commonly used to determine the forming limit curve of sheet metals, and is focused on the interaction between the friction conditions and the deformation behaviour of a dual phase steel. The methodology is based on the finite element analysis of the Nakajima test, considering different values of the classic Coulomb friction coefficient, including a pressure-dependent model. The validity of the finite element model is examined through a comparison with experimental data. The results show that friction affects the location and strain path of the necking point by changing the strain rate distribution in the specimen. The strain localization alters the contact status from slip to stick at a portion of the contact area from the pole to the necking zone. This leads to the sharp increase of the strain rate at the necking point, as the punch rises further. The influence of the pressure-dependent friction coefficient on the deformation behaviour is very small, due to the uniform distribution of the contact pressure in the Nakajima test. Moreover, the low contact pressure range attained cannot properly replicate real contact condition in sheet metal forming processes of advanced high strength steels.


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