Structure–properties’ modification of 70/30 brass by large-load and low-speed friction stir processing

ABSTRACT

A novel one-step approach named large-load and low-speed friction stir processing was developed to produce an ultrafine-grain structure in 70/30 brass. The material so processed was characterised by a mean grain size of 0.5 µm and high angle boundaries of 91%. Abundant twin boundaries and stacking fault were produced in the grains as well. The grain refinement mechanism is attributed to the combination of discontinuous dynamic recrystallisation (DRX), microshear bands assisted DRX and twinning-induced DRX. A good combination of yield strength and uniform strain was achieved. This study provides a simple and effective method to improve the microstructure and mechanical properties in metals and alloys with low stacking fault energy.

KEYWORDS:

• Metals and alloys
• friction stir processing
• recrystallisation
• grain boundaries
• mechanical properties

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was financial supported by National Natural Science Foundation of China (No. 51805145), Natural Science Foundation of Jiangsu Province (No. BK20160284) and Fundamental Research Funds for the Central Universities of PR China (No. 2018B22514).