Solutions for Hydrogen-Induced Delayed Fracture in Hot Stamping

2014 ◽  
Vol 1063 ◽  
pp. 32-36 ◽  
Author(s):  
Hong Zhou Lu ◽  
Shi Qi Zhang ◽  
Bian Jian ◽  
Hardy Mohrbacher ◽  
Ai Min Guo
Keyword(s):  
Automotive Industry ◽  
Fracture Resistance ◽  
Hot Stamping ◽  
Passive Safety ◽  
Effective Solution ◽  
Delayed Fracture ◽  
Press Hardening ◽  
Car Body ◽  
Hot Stamping Steel ◽  
Press Hardening Steel

One of the main targets in automotive industry is to reduce the weight of vehicle as well as increase the safety. To accomplish this goal, press-hardening steel and hot stamping parts have been used in car body. However, the possibility of hydrogen-induced delayed fracture (HDF) of hot stamping parts exits, which will decrease the car’s passive safety. A solution has been presented to reduce the sensitivity of HDF and improve hydrogen-induced delayed fracture resistance (HDFR) by Niobium micro-alloying technology. Traditional press-hardening steel 22MnB5 and new steel 22MnBNb2, 22MnBNb5 and 22MnBNb7 were studied, and it is shown that the appropriate addition of Nb is beneficial to the improvement of the delayed fracture resistance of the hot stamping steel, which indicates that Niobium micro-alloying technology is an effective solution to the HDF in hot stamping steels.

Hot Stamping Technology Applied on Vehicles on EuroCarBody

2014 ◽  
Vol 1063 ◽  
pp. 232-236 ◽  
Author(s):  
Jia Zhou ◽  
Ming Tu Ma
Keyword(s):  
Joule Heating ◽  
Automotive Industry ◽  
New Technologies ◽  
Commercial Vehicle ◽  
State Of The Art ◽  
Hot Stamping ◽  
Tailor Rolled Blank ◽  
Press Hardening ◽  
The Press ◽  
Body In White

EuroCarBody, offer the most important forum for defining and discussing the state of the art in modern series car body engineering. The present paper concerns the materials of press hardened steels and its’ manufacturing technology (Hot stamping) applied on vehicle on EuroCarBody from 2009 to 2013 through presentations and benchmark datas. The using percentage of press hardening steels (PHS) on body in white (BIW) are summarized and analyzied. It can be noted that the number and weight of BIW parts using of press hardening steels are increasing from 2009 to 2013, some kind of vehicle, such as Audi A3, the using percentage of PHS reaches 21.6%. The press hardening steels have started used on commercial vehicle from EuroCarBody 2013. More and more new technologies applied on hot stamping processing, such as Joule heating for hot stamping, Hot-form-process partial tempering, Tailor Rolled Blank (TRB) technolgy, etc. With the developing of the automotive industry, more and more hot forming parts will be applied on vehicles in the future.

Effects of Austenitizing Temperature on Microstructure and Properties of Hot-Formed Steel

2014 ◽  
Vol 1063 ◽  
pp. 88-92 ◽  
Author(s):  
He Long Cai ◽  
Peng Ju Du ◽  
Hong Liang Yi ◽  
Di Wu
Keyword(s):  
Mechanical Properties ◽  
Hot Stamping ◽  
High Strength ◽  
Hardened Steel ◽  
Austenitizing Temperature ◽  
Austenitization Temperature ◽  
Press Hardening ◽  
Automotive Structures ◽  
Body In White ◽  
Press Hardening Steel

Press hardening steel is the best solution for application of extremely high strength steel in automotive structures in order to reduce the weight of body-in-white. Effect of austenitizing temperature on the grain coarsening of a press hardening steel has been investigated by using dilatometer at first. The mechanical properties of press-hardened steel austenitized at temperature between 850 to 950oC by using a pilot hot stamping line have been investigated. The strength, especially the ultimate tensile strength, was improved by the grain refinement with lower austenitization temperature.

scholarly journals Constitutive characterization of an 1800 MPa press hardening steel under hot stamping conditions

2021 ◽  
Vol 1157 (1) ◽  
pp. 012012
Author(s):  
S Lu ◽  
S DiCecco ◽  
M Worswick ◽  
C Chiriac ◽  
G Luckey ◽  
...  
Keyword(s):  
Hot Stamping ◽  
Press Hardening ◽  
Press Hardening Steel

New Generation Press Hardening Steels with Tensile Strength of 1.7-2.0 GPa and Enhanced Bendability

2021 ◽  
Author(s):  
Sarah Tedesco ◽  
Ming Shi ◽  
Jason Coryell ◽  
Qi Lu ◽  
Jianfeng Wang
Keyword(s):  
Tensile Strength ◽  
Automotive Industry ◽  
The Novel ◽  
Component Level ◽  
Press Hardening ◽  
Crash Protection ◽  
Oxidation Resistant ◽  
Light Weighting ◽  
New Generation ◽  
Press Hardening Steel

Abstract Press hardening steel (PHS) applications predominately use 22MnB5 AlSi coated in the automotive industry. This material has a limited supply chain. Increasing the tensile strength and bendability of the PHS material will enable light-weighting while maintaining crash protection. In this paper, a novel PHS is introduced, and properties are compared to 22MnB5. The new Coating Free PHS (CFPHS) steel, 25MnCr, has increased carbon, with chromium and silicon additions for oxidation resistance. Its ultimate tensile strength (UTS) of 1.7 GPa with bending angle above 55° at 1.4mm thickness improves upon the 22MnB5 grade. This steel is not pre-coated, is oxidation resistant at high temperature, thus eliminating the need for AlSi or shot blasting post processing to maintain surface quality. Microstructural mechanisms used to enhance bendability and energy absorption are discussed for the novel steel. Performance evaluations such as: weldability, component level crush and intrusion testing and e-coat adhesion, are conducted on samples from industrial coils.

Investigation on Properties and Microstructure in Hot Stamping Operation of Rear Axle Beams

2014 ◽  
Vol 1063 ◽  
pp. 143-147
Author(s):  
Xiao Chun Jin ◽  
Yong Shen Xue ◽  
Qing Nan Ma ◽  
Mei Zhang ◽  
Lin Li
Keyword(s):  
Automotive Industry ◽  
Rear Axle ◽  
Heating Temperature ◽  
Hot Stamping ◽  
High Strength Steels ◽  
High Strength ◽  
Basic Knowledge ◽  
Boron Steel ◽  
Temperature Boundary ◽  
Hot Stamping Steel

In the automotive industry, the hot forming of high strength steels offers the possibility to obtain significant reduction of weight without affecting the structural performances of final products. The main reason of its restricted application in the industry lies however in the lack of basic knowledge about mechanical and microstructural characteristics of sheets at elevated temperature, boundary conditions, and other process parameters. To partially overcome this limitation, this paper presents a research on the material properties of the hot stamping steel 22MnB5. Sheets of boron steel 22MnB5 with a thickness of 3.8mm were investigated and the results of experimental hot stamping tests were considered. The yield strength (YS) reached about 1200MPa, tensile strength (TS) reached 1500MPa, microhardness reached over 450HV at heating temperature of 880°C and holding 5 min.

scholarly journals Alloy Optimization for Reducing Delayed Fracture Sensitivity of 2000 MPa Press Hardening Steel

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 853 ◽  
Author(s):  
Hardy Mohrbacher ◽  
Takehide Senuma
Keyword(s):  
Tensile Strength ◽  
Hydrogen Embrittlement ◽  
Alloying Elements ◽  
Steel Alloy ◽  
Delayed Fracture ◽  
Press Hardening ◽  
Automotive Body ◽  
Body Design ◽  
Delayed Cracking ◽  
Press Hardening Steel

Press hardening steel (PHS) is widely applied in current automotive body design. The trend of using PHS grades with strengths above 1500 MPa raises concerns about sensitivity to hydrogen embrittlement. This study investigates the hydrogen delayed fracture sensitivity of steel alloy 32MnB5 with a 2000 MPa tensile strength and that of several alloy variants involving molybdenum and niobium. It is shown that the delayed cracking resistance can be largely enhanced by using a combination of these alloying elements. The observed improvement appears to mainly originate from the obstruction of hydrogen-induced damage incubation mechanisms by the solutes as well as the precipitates of these alloying elements.

Friction and wear mechanisms during hot stamping of AlSi coated press hardening steel

Wear ◽  
2017 ◽  
Vol 380-381 ◽  
pp. 137-145 ◽  
Author(s):  
J. Venema ◽  
D.T.A. Matthews ◽  
J. Hazrati ◽  
J. Wörmann ◽  
A.H. van den Boogaard
Keyword(s):  
Wear Mechanisms ◽  
Friction And Wear ◽  
Hot Stamping ◽  
Press Hardening ◽  
Friction And Wear Mechanisms ◽  
Press Hardening Steel

scholarly journals Investigation of the Microstructural Evolution during Hot Stamping of a Carburized Complex Phase Steel by Laser-Ultrasonics

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1836
Author(s):  
Alexander Horn ◽  
Marion Merklein
Keyword(s):  
Microstructural Evolution ◽  
Hot Stamping ◽  
Laser Ultrasonics ◽  
Complex Phase ◽  
Finished Steel ◽  
Steel Sheets ◽  
Fine Grain ◽  
Martensitic Microstructure ◽  
Ultrasound Sensor ◽  
Hot Stamping Steel

Prior carburization of semi-finished steel sheets is a new process variant in hot stamping to manufacture parts with tailored properties. Compared to conventional hot stamping processes, a complex phase typed steel alloy is used instead of 22MnB5. Yet recent investigations focused on final mechanical properties rather than microstructural mechanisms cause an increase in strength. Thus, the influence of additional carburization on the microstructural evolution during hot stamping of a complex phase steel CP-W®800 is investigated within this work. The phase transformation behavior, as well as the grain growth during austenitization, is evaluated by in-situ measurements employing a laser-ultrasound sensor. The results are correlated with additional hardness measurements in as-quenched condition and supplementary micrographs. The experiments reveal that the carburization process significantly improves the hardenability of the CP-W®800. However, even at quenching rates of 70 K/s no fully martensitic microstructure was achievable. Still, the resulting hardness of the carburized samples might exceed the fully martensitic hardness of 22MnB5 derived from literature. Furthermore, the carburization process has no adverse effect on the fine grain stability of the complex phase steel. This makes it more robust in terms of grain size than the conventional hot stamping steel 22MnB5.

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