Study On Microstructure And Properties Of Low Alloy Wear-resistant Steels

For the low alloy wear-resistant steel working at abrasive wear, not only high hardness and high tenacity, but also good wear resistance are required to meet the demand for their performance. According to the working condition and the failure analysis of the cold sieve plate, this article designed four groups of composition of the low alloy wear-resistant steel. The content of Cr, Ni, Si, Mn, Re, and B are almost same, but C and Mo content were different. Some groups of different quenching and tempering temperatures were designed. The microstructure of the low alloy wear-resistant steel at as-cast and after heat treatment was analyzed through the metallographical observing and X-ray diffraction. Rockwell hardness test and the impact toughness test were carried on the low alloy wear-resistant steel. The wear resistance of this experiment material after heat treatment was tested by ML-100 abrasive wear testing machine. The impact fracture of the impact specimen and the surface morphology were scanned with SEM. The influence of the abrasive dimension to the wear resistance of the experiment material was researched.The experiment results were below: The as-cast microstructure of the low alloy wear-resistant steel was pearlite . The matrix was lath-shaped martensite and also a small amount of austenite and carbide after heat treatment. The carbide increased as the content of C increases. The carbide existed dispersedly on the matrix and can improve the hardness of the experiment material, but a little damage to the toughness of the material. The microstructure and the mechanical properties were the best after the heat treatment of that the quenching temperature is 910℃, with holding time of 1 hour, and the tempering temperature is 230℃, with holding time of 2 hours. The hardness reached to HRC50 and impact toughness 45 J/cm~2. The hardness increased and the toughness declines as the quenching temperature heighten. The dimple of the fracture of the impact specimen was deep and was gliding fracture after SEM scanning. The wear...