Effect of solution treatment on microstructure and properties of 00Cr32Ni7Mo3.5N

ABSTRACT

00Cr32Ni7Mo3.5N parts were prepared by hot isostatic pressing (HIP) and forging process in this study. The effect of solution heat treatment on microstructure, mechanical properties and pitting resistance were investigated. Under solution treating at 1100°C, the phase constitution in HIP parts can be adjusted to comprise approximately 50% austenite (γ) and 50% ferrite (δ) phases with equiaxed structure, and this post-processing can meanwhile help to dissolve precipitated brittle σ phase. In comparison, the banded dual-phase structures in forged counterparts cannot be removed even after annealing at 1200°C. The desired phase proportion after solution treatment plus the equiaxed grains impart superior comprehensive performance to HIP parts with the tensile strength of 886 MPa, elongation of 48.0%, impact energy of 83 J, and pitting potential of 0.9659 V in neutral 3.5 wt-% NaCl solution. Based on this work, HIP seems to be a promising method to fabricate near-net-shape 00Cr32Ni7Mo3.5N parts.

Highlights

1. SAF3207 were prepared by HIP and was compared with its forging parts.

2. HIP samples show equiaxed structure, while forgings are banded dual phase structures.

3. Phase constitution can be adjusted to be approximately 50% austenite and 50% ferrite.

4. The brittle σ phase can be completely removed after solution treatment.

5. HIP seems a promising method to fabricate SAF3207 with high performance.

GRAPHICAL ABSTRACT

KEYWORDS:

• 00Cr32Ni7Mo3.5N
• hot isostatic pressing
• forging
• solution treatment
• microstructure
• properties

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Fundamental Research Funds for the Central Universities, , China [grant number FRF-NP-20-08, FRF-MP-20-22]; National Natural Science Foundation of China [grant number 51874038]; Key-Area Research and Development Program of Guangdong Province, China [grant number 2019B010942001].

Notes on contributors

Yang Zhao

Yang Zhao is currently a PhD candidate in Institute for Advanced Materials and Technology, University of Science and Technology Beijing. Her current research focuses on powder metallurgy steels and shape memory alloys.

Jianhao Chen

Jianhao Chen is currently a PhD candidate in the School of Engineering at Deakin University in Geelong, Australia. His current research focuses on additive manufacturing of titanium alloys for advanced structural applications; solidification and solid-state phase transformation of Ti-6Al-4V alloy manufactured by laser powder-bed fusion technology. Prior to this role, Jianhao had been working as a research assistant for his master’s degree at the Institute for Advanced Materials and Technology in the University of Science and Technology Beijing from 2014 to 2017, leading the programs of design and development of high-performance steel products by powder metallurgy, and advanced copper matrix composites, under Prof. Shubin Ren’s supervision.

Meihuan Qi

Meihuan Qi Master graduated of Material Science and Engineering in University of Science and Technology Beijing, was mainly devoted to research of powder metallurgy steels.

Shubin Ren

Shubin Ren is a professor in the Institute for Advanced Materials and Technology, University of Science and Technology Beijing. His current research interests are mainly the preparation, forming and application of metal powders.

Xuanhui Qu

Xuanhui Qu is a professor in the Institute for Advanced Materials and Technology, University of Science and Technology Beijing. His current research interests are mainly in the preparation and application of metal materials by powder metallurgy.