Fundamentals and Applications of Hot Stamping Technology for Producing Crash-Relevant Automotive Parts

Improving crashworthiness and reducing weight are two contradicting requirements in automotive industry. To fulfill both requirements, lightweight metals such as aluminum or magnesium, or high strength steels are used. Typically in high strength steels and aluminum alloys, high springback and low formability are observed. One method to form ultra high strength steels is “Hot Stamping”. In this method, Manganese Boron alloyed steels can be hot formed and quenched in the die. The final product has Yield Stress over 1000 MPa (145 ksi) and Tensile Strength over 1500 MPa (215 ksi). Hot stamped components have been used in automotive industry since 1980’s but have seen a major breakthrough in 2006. Since then the number of hot stamped components have increased. Today, some vehicles have more than 20% of their body weight composed of hot stamped steels. After quenching, steels typically have low elongation, which reduces their energy absorption performance. To solve this problem, tailored hot stamped components have been used. These can be conventional tailor-welded or tailor-rolled blanks. Hot stamping makes a new type of tailored part possible, by tailoring the microstructure. This brings more challenging conditions, as temperature and microstructure evolutions have to be precisely predicted. In addition, distortion may be an issue in tailored parts, as hard zones will be quenched to martensite and soft zones may have other phases.To design a robust hot stamping process, simulation of forming, heat transfer and phase transformations have to be solved concurrently. The major objective of this study is to address these issues and to use Finite Element (FE) simulations to predict: 1) presence of defects, 2) thickness and hardness distribution, 3) distortion of the part and 4) repeatability of the process. Several case studies from literature and from participating companies have been simulated using PamStamp to predict final properties. These are either compared to literature or validated with experimental measurements conducted at partner companies. Overall, a library of material properties (for blank and tool materials) and other inputs (thermal boundary conditions, etc.) for simulation of hot stamping process is defined. Several approximations of hardness and tensile strength from phase transformations are investigated and validated with measurements.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor dc:publisher

The Ohio State University

Year dc:date

2013

Author dc:creator

• Billur, Eren

Contributors dc:contributor

• Altan, Taylan

• Mechanical Engineering
• Hot Stamping
• Press Hardening
• Metal Forming

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1366243664

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1366243664