Research on metal wear-resistant materials (2)
(3) Aube ductile iron series wear-resistant cast iron bainite-martensitic wear-resistant ductile iron is heat-treated by austempering or adding alloy elements to transform the matrix into bainite-ferrite matrix with residual austenite The body structure has the advantages of high strength, good plasticity, and high dynamic load performance such as bending fatigue and contact fatigue. It has been used in gears, camshafts, automobile traction hooks and other wearable parts at home and abroad. The application of Aube ductile iron in my country is still limited to middle and low-grade products, and has not yet reached the level of industrial production. It is mainly used in the production of structural parts such as wedge irons and crankshafts for railway wagons, as well as the production of wear-resistant parts such as grinding balls and hammer heads. Some studies and applications have been carried out in the production of bainite ductile iron pipes, liners, gears and rolls.
(4) Steel-based wear-resistant composite materials Steel-based wear-resistant composite materials use steel as the bonding metal and refractory metal carbide as the bonding material for the hard phase, and have been industrially applied in some severe wear conditions. Its microstructure is characterized by fine hard grains evenly dispersed in the steel matrix, which has the hardness and wear resistance of hard compounds, as well as the strength and toughness of steel, and is in the middle of ordinary hard alloys and steel. However, the most commonly used additive elements for binders are rare metals such as nickel and chromium, and powder metallurgy methods, impregnation methods, hot pressing methods, hot isostatic pressing methods, spray forming methods, mixing and stirring casting methods and plasma melting powder methods are required. and other processing methods.
(5) Medium and low alloy wear-resistant steel has good wear-resistant structure, which can provide high hardness and sufficient toughness. The research results show that: ①The lath martensite has smaller fracture units and more tears during quasi-cleavage fracture, which consumes the fracture work, thus improving the toughness. ②The lower bainite uses ferrite laths with different orientations as the minimum fracture unit, and its toughness is higher than that of tempered martensite with the same hardness. ③Retained austenite exists in martensite or lower bainite structure, which can relax stress, hinder crack expansion, increase energy absorption when the material breaks, and improve toughness. ④ Fine and dispersed carbides are beneficial to wear resistance.
The quenched microstructures in medium and low alloy steels include martensite (lath, sheet), bainite, retained austenite and carbides, and the above microstructures can be obtained. The alloy element content (mass fraction) of this type of steel is low, generally low alloy steel is 3% to 15%, medium alloy steel is 6% to 18%, and the added alloy elements are rich in domestic resources, which are easy to popularize and apply; High hardness, comprehensive performance of sufficient toughness, in the case of hardness > 50HRC, toughness. The value can reach 20-40J/cm, and the matching relationship between hardness and toughness can be controlled in a wide range. It can obtain good wear resistance under various abrasive wear conditions, and has broad application prospects and promotion significance. .
