# Computational material design for Q&P steels with plastic instability theory

## Abstract

In this paper, the deformation limits of Quenching and Partitioning (Q&P) steels are examined with the plastic instability theory. For this purpose, the constituent phase properties of various Q&P steels were first experimentally obtained, and used to estimate the overall tensile stress-strain curves based on the simple rule of mixture (ROM) with the iso-strain and iso-stress assumptions. Plastic instability theory was then applied to the obtained overall stress-strain curves in order to estimate the deformation limits of the Q&P steels. A parametric study was also performed to examine the effects of various material parameters on the deformation limits of Q&P steels. Computational material design was subsequently carried out based on the information obtained from the parametric study. The results show that the plastic instability theory with iso-stress-based stress-strain curve may be used to provide the lower bound estimate of the uniform elongation (UE) for the various Q&P steels considered. The results also indicate that higher austenite stability/volume fractions, less strength difference between the primary phases, higher hardening exponents of the constituent phases are generally beneficial for the performance improvement of Q&P steels, and that various material parameters may be concurrently adjusted in a cohesive way in order to improve themore »

- Authors:

- Publication Date:

- Research Org.:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 1390412

- Report Number(s):
- PNNL-SA-124204

Journal ID: ISSN 0264-1275; 453060037

- DOE Contract Number:
- AC05-76RL01830

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Materials & Design; Journal Volume: 132; Journal Issue: C

- Country of Publication:
- United States

- Language:
- English

### Citation Formats

```
Cheng, G., Choi, K. S., Hu, X. H., and Sun, X.
```*Computational material design for Q&P steels with plastic instability theory*. United States: N. p., 2017.
Web. doi:10.1016/j.matdes.2017.07.029.

```
Cheng, G., Choi, K. S., Hu, X. H., & Sun, X.
```*Computational material design for Q&P steels with plastic instability theory*. United States. doi:10.1016/j.matdes.2017.07.029.

```
Cheng, G., Choi, K. S., Hu, X. H., and Sun, X. Sun .
"Computational material design for Q&P steels with plastic instability theory". United States.
doi:10.1016/j.matdes.2017.07.029.
```

```
@article{osti_1390412,
```

title = {Computational material design for Q&P steels with plastic instability theory},

author = {Cheng, G. and Choi, K. S. and Hu, X. H. and Sun, X.},

abstractNote = {In this paper, the deformation limits of Quenching and Partitioning (Q&P) steels are examined with the plastic instability theory. For this purpose, the constituent phase properties of various Q&P steels were first experimentally obtained, and used to estimate the overall tensile stress-strain curves based on the simple rule of mixture (ROM) with the iso-strain and iso-stress assumptions. Plastic instability theory was then applied to the obtained overall stress-strain curves in order to estimate the deformation limits of the Q&P steels. A parametric study was also performed to examine the effects of various material parameters on the deformation limits of Q&P steels. Computational material design was subsequently carried out based on the information obtained from the parametric study. The results show that the plastic instability theory with iso-stress-based stress-strain curve may be used to provide the lower bound estimate of the uniform elongation (UE) for the various Q&P steels considered. The results also indicate that higher austenite stability/volume fractions, less strength difference between the primary phases, higher hardening exponents of the constituent phases are generally beneficial for the performance improvement of Q&P steels, and that various material parameters may be concurrently adjusted in a cohesive way in order to improve the performance of Q&P steel. The information from this study may be used to devise new heat treatment parameters and alloying elements to produce Q&P steels with the improved performance.},

doi = {10.1016/j.matdes.2017.07.029},

journal = {Materials & Design},

number = C,

volume = 132,

place = {United States},

year = {Sun Oct 01 00:00:00 EDT 2017},

month = {Sun Oct 01 00:00:00 EDT 2017}

}