Microstructural and Mechanical Characteristics of Novel 6% Cr Cold-Work Tool Steel

Singon Kang,Minwook Kim,Seok-Jae Lee

doi:10.3390/met7010012

Singon Kang, Minwook Kim + Show 1 more

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https://doi.org/10.3390/met7010012

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Journal: Metals	Publication Date: Jan 6, 2017
Citations: 8	License type: CC BY 4.0

Affiliation: Colorado School of Mines, Jeonbuk National University

Abstract

We investigated a new cold-work tool steel with a low Cr content of 6 wt. % which was designed based on thermodynamic calculation to minimize the formation of primary carbide. A smaller particle size and a smaller volume fraction of carbides were observed in this 6% Cr steel. Superior mechanical properties in terms of hardness, impact toughness, tensile strength, and total elongation were achieved in this steel, due to fine secondary carbides precipitated during tempering. These carbide particles were M6C and (Mo,V)C carbides with a diameter below 100 nm.

Highlights

The recent trend in the automotive industry is to enhance the use of advanced high-strength steel (AHSS), which reduces the weight of vehicles and improves fuel efficiency
In the STD11 steel, the solidification temperature was 1248 ◦ C, but the primary M7 C3 carbide appeared at the higher temperature of 1252 ◦ C. It indicates that the M7 C3 carbide can be precipitated before the full solidification and the precipitates coarsened during the following thermo-mechanical processing, which had a damaging influence on the mechanical properties
The solidification in the Cr6C9 steel was completed at 1244 ◦ C, similar to the STD11 steel

Summary

Introduction

The recent trend in the automotive industry is to enhance the use of advanced high-strength steel (AHSS), which reduces the weight of vehicles and improves fuel efficiency. The use of high-strength tool steels is required for various metal working processes, e.g., press forming or drawing. For an effective metal working process, basically, the strength of tool steels should be higher than that of AHSS which is fabricated using the tool steels. This means that the development of tool steels tends to take precedence over the development of AHSS as there is a huge demand for AHSS with a strength higher than 1 GPa. The tool steels mainly consist of high C, high Cr, and other carbide-forming elements such as. The mechanical properties of the tool steels can be influenced by altering the tempering condition, which is related to the type and amount of carbides formed during tempering

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Conclusion