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About this book

Providing a comprehensive overview of hot stamping (also known as ‘press hardening’), this book examines all essential aspects of this innovative metal forming method, and explores its various uses. It investigates hot stamping from both technological and business perspectives, and outlines potential future developments. Individual chapters explore topics such as the history of hot stamping, the state of the art, materials and processes employed, and how hot stamping is currently being used in the automotive industry to create ultra-high-strength steel components. Drawing on experience and expertise gathered from academia and industry worldwide, the book offers an accessible resource for a broad readership including students, researchers, vehicle manufacturers and metal forming companies.

Table of Contents

Frontmatter

Chapter 1. Introduction

Vehicle manufacturers are under pressure of reducing fuel consumption and greenhouse gas emissions and still improving safety. One method to reduce the consumption and emissions is to make the vehicles lighter. Several approaches are employed to make cars lighter and yet stronger to ensure safety standards:
(1)
to use high strength-to-weight ratio materials (higher strength steels, Aluminum, Magnesium, Carbon Fiber Reinforced Polymers, etc.) and
 
(2)
to reduce the material use wherever possible.
 
This chapter discusses the material requirements in a car body, steel grades used in automotive industry and introduces the hot stamping process.
Eren Billur

Chapter 2. Metallurgy of Steels

In hot stamping, typically, C-Mn-B alloyed steels are used and the process involves phase transformations. Thus, a clear understanding of the effects of alloying elements, different phases of steels, and their kinematics are critical for comprehensive understanding of the process.
Barıs Çetin, Halim Meço

Chapter 3. History and Future Outlook of Hot Stamping

Hot stamping can be traced back to traditional Japanese sword making techniques of thirteenth–fourteenth centuries [1]. The earliest patent about “Preßhärten” (Press hardening) was granted in 1914 in Switzerland. The technique described in this patent has been used in agricultural products since 1930s [2]. Hot stamping, as we know it today differs from these applications since the quenching is done at the press die to reduce distortion. Although hot stamping has been commonly used since early to mid-2000s, the beginning was in 1970s.
Eren Billur, Göran Berglund, Tord Gustafsson

Chapter 4. Blank Materials

All sheet metal forming operations start with the blank material. The final part properties are dependent on the incoming material properties and how they could be changed during the process. To engineer the final part, it is essential to understand the incoming blank material. This chapter discusses the most common 22MnB5 steel, and other steel grades already in use or proposed to be used in hot stamping processes. Incoming blank could be uncoated or coated. Coatings can affect the final properties due to scale formation, decarburization and by the presence of microcracks. In the last decade, tailored blanks have been used in a number of automotive applications. The last section of this chapter summarizes Tailor Rolled, Patchwork, Tailor Welded blanks, and their combinations.
Eren Billur, Hyun-Sung Son

Chapter 5. A Hot Stamping Line

Hot stamping requires a special production line, similar to but different than cold stamping operations. A typical hot stamping line consists of (1) a furnace/heating system, (2) a material handling system, (3) a press, and (4) an exit line. Sometimes trimming/piercing systems could also be included in the definition of “a line”. In this chapter, the first three items are explained in detail.
Jan Jonasson, Eren Billur, Aitor Ormaetxea

Chapter 6. Die Design and Manufacturing

In typical (cold) stamping operations, the dies are only used to plastically deform the metal material. In hot stamping, on the other hand, the dies are used to form the material and extract the heat energy from the blank. All this has to be done as quickly as possible to improve the part quality (to ensure martensite formation is completed) and part productivity. This chapter discusses the requirements from a hot stamping die, how they are designed, and how they are manufactured.
Eren Billur, Takehide Senuma

Chapter 7. Post-Forming Operations

Once an automotive part is formed and quenched, it may be required to trimmed/pierced, shot blasted (depending on the coating) and then welded to subassemblies and assemblies. It is essential to understand all these steps of manufacturing. After each and every step, quality control—both online and offline—has to be done. This chapter discusses the so-called “Post-Forming Operations”.
Eren Billur, Felix Quasniczka

Chapter 8. Tailored Properties

Depending on the performance expectations or to facilitate trimming, improve weldability, a single component may be required to have different local properties. The so-called tailored parts can be produced by incoming tailored blanks. It is also possible to have a standard blank, and can be processed in a hot stamping line to have tailored properties. The aim of this chapter is to give a better understanding to the reader about hot stamped parts having tailored properties in body-in-white applications.
Eren Billur, Vladimir Bošković

Chapter 9. Hot Tube Forming

Tube forming is used to manufacture hollow geometries, otherwise would be stamped and welded. Automotive components could be produced by simply bending and preforming of tubular blanks; or by tube hydroforming (THF). Until recently, THF was limited to aluminum alloys and steels up to 1000 MPa tensile strength. Nowadays, hot tube hydroforming and tube bending & quenching processes are used in automotive industry to produce complex parts over 1500 MPa tensile strength.
Eren Billur, Frank Schieck

Chapter 10. Computer Modeling of Hot Stamping

Tool design based on computer models is nothing new for stamping industry. Although mostly the same software packages are used for cold and hot stamping simulations, simulation of hot stamping differs significantly; as it is not only a mechanical simulation. Hot stamping is a multiphysics problem with heat transfer, metallurgical transformations and even fluid dynamics in the cooling channels.
Harald Porzner, Eren Billur

Chapter 11. Economics of Hot Stamping

Hot stamping industry includes several businesses, including, steel makers, die makers, equipment suppliers, Tier suppliers, and automotive OEM’s. The industry is composed of more than 100 companies and exceeds USD 6 Billion of annual revenue. This chapter reviews the industry and gives a future outlook from automotive and defense industries. Please note that this chapter is derived from publicly available data, and includes co-authors’ personal opinions as well.
Eren Billur, Rick Teague, Barış Çetin
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