Alloy wear-resistant castings Generally, cobalt-chromium-tungsten alloys lack a coherent strengthening phase. Although the medium-temperature strength is low (only 50-75% of nickel-based alloys), it has higher strength and good thermal fatigue resistance above 980 °C. It is resistant to hot corrosion and abrasion and has good weldability. Suitable for the production of air jet engines, industrial gas turbines, guide vanes and nozzle guide vanes for marine gas turbines, and diesel engine nozzles. Carbide-fortified phase The most important carbides in cobalt-chromium-tungsten alloys are MC, M23C6 and M6C. In cast cobalt-chromium-tungsten alloys, M23C6 precipitates between grain boundaries and dendrites when slowly cooled. In some alloys, fine M23C6 can form a co-crystal with the matrix γ. The MC carbide particles are too large to directly affect the dislocations directly, so the strengthening effect on the alloy is not obvious, and the finely dispersed carbides have a good strengthening effect.
Wear-resistant castings only form the standardization of the extrusion casting mold design, in order to make it faster and better development. After the castings are taken out of the cast-cooled mold, there are gates, risers, metal burrs, drapes and mold lines. The sand-cast castings are also adhered to the sand and must be cleaned. Equipment for performing such work includes a sanding machine, a shot blasting machine, a pouring riser cutting machine, and the like. The sand falling of sand castings is a process with poor working conditions. Therefore, when selecting the modeling method, it should be considered to create convenient conditions for the falling sand cleaning. Some castings are subject to special post-processing requirements such as heat treatment, shaping, anti-rust treatment, roughing, etc. The casting process can be divided into three basic parts, namely casting metal preparation, mold preparation and casting processing. Cast metal refers to the metal material used for casting castings in casting production. It is an alloy composed mainly of a metal element and added with other metal or non-metal elements. It is customarily called cast alloy, mainly cast iron. Cast steel and cast non-ferrous alloys.
The quality of raw materials for casting of wear-resistant castings. The quality of metal charge, refractory, fuel, flux, modifier and foundry sand, sand binder, paint and other materials will be substandard, which will cause defects such as pores, pinholes, slag inclusions and sand sticking in cast iron parts, affecting cast iron parts. Appearance quality and internal quality, when severe, will scrap iron castings. The design and craftability of cast iron parts. When designing, in addition to determining the geometry and size of the cast iron according to the working conditions and the properties of the metal material, the rationality of the design must be considered from the perspective of the casting alloy and the characteristics of the casting process, namely the apparent size effect and solidification, Shrinkage, stress and other problems to avoid or reduce the occurrence of defects such as segregation, deformation, cracking of cast iron parts. Generally, for the appearance quality of professional cast iron parts, the comparative sample can be used to judge the surface roughness of the casting; the fine cracks on the surface can be inspected by the coloring method and the magnetic powder method. High-chromium cast iron with a chromium content of 12-30% and a carbon content of 2.4-3.6%. The matrix of martensite or austenite or a mixture of the two can be obtained by high alloying and heat treatment. Special carbides of chromium.https://www.wuxiorient.com/