Erosion mechanism of high strength and toughness medium manganese steel under simulated scour of Yellow River water and sediment

Abstract

The MCF-30 testing machine was used to simulate scour of Yellow River Water and Sediment, and the eroding mechanism of high strength and tough medium Mn steel and the relationship of the anti-abrasion performance and mechanical properties with several materials used for pump impeller were studied. The results show that the microcracking is often initiated at the interfaces of austenite and martensite and gradually develops into cavitation pits, the latter finally grows to much larger scale pits due to aggravated cavitation and damage caused by water and sediment impact. At the same time, the increase of phase interface leads to the decrease of the anti-abrasion performance. As the temperature increases, the austenite volume fraction of medium Mn steel increases from 16.4% to 22.9%, and the mass loss rate increases from 2.6 g·m-2·h-1 to 7.8 g·m-2·h-1. In addition, both mechanical properties and abrasion mass loss of studied medium Mn steel are compared with several metallic materials currently used in pump impeller of Yellow River.It was found that higher hardness leads to reduce erosion mass loss in the case of no occurrence of brittle macrocracking; when the materials undergo plastic deformation during scouring, ultimate tensile strength determines the anti-abrasion resistance; in the case of similar hardness, higher ductility and toughness may also improve abrasion resistance. Since the developed medium Mn steel has the better combination of tensile strength-work hardening ability-hardness-toughness than other materials currently used, it is expected to have a high potential of being used in pump impellor with prolonged life for the irrigation works of Yellow River.

Keywords

• medium mn steel
• mechanical property
• retained austenite
• erosion mechanism