The elements in wear-resistant alloy steel significantly influence its subsequent tempering, processing, and cutting performance. Excessive residual elements can also affect the quality of wear-resistant alloy steel castings. How should cast steel manufacturers control these elements, and what is their impact on the castings themselves?

1. Impact on the weldability and machinability of steel:

Cast steel manufacturers want to measure the process performance of steel. Weldability and machinability are key aspects of this. All alloying elements that improve hardenability compromise the weldability of steel because, upon cooling on the side of the weld heat-affected zone near the fusion line, hard and brittle microstructures such as martensite are easily formed. On the other hand, this may lead to cracking. Due to high temperatures, the grains near the fusion line of the heat-affected zone tend to become coarse. Therefore, elements that refine the grain size, such as titanium and vanadium, are beneficial in wear-resistant alloy steel.

Cast steel manufacturers can improve the machinability of steel by adding appropriate amounts of sulfur, lead, and other elements. Alloying elements in wear-resistant alloy steel generally increase the hardness of the steel, thus increasing the cutting resistance and exacerbating tool wear. The machinability of steel is affected by the matrix structure of the steel, the type, shape, and quantity of inclusions.

2. Impact on the mechanical properties and tempering performance of steel:

The properties of steel mainly depend on the properties and relative distribution of the iron solid solution and carbides. The influence of alloying elements on the mechanical properties of steel is also closely related to this. Alloying elements dissolved in ferrite play a solid solution strengthening role, improving the hardness and strength of steel, but at the same time reducing the toughness and plasticity of steel.

The ductile-brittle transition temperature of quenched and tempered steel in cast steel plants is an important indicator for evaluating its mechanical properties.

(1) Elements that can lower the transition temperature are nickel and manganese.

(2) Elements that can raise the transition temperature include boron, silicon, molybdenum, copper, and chromium.

(3) Al element will slightly lower the transition temperature and significantly raise the transition temperature.

(4) Ti and V elements can slightly raise the transition temperature and significantly lower the transition temperature.

Wear-resistant alloy steel has better tempering stability than carbon steel because alloying elements hinder the diffusion of atoms in steel during tempering. Therefore, at the same temperature, it can delay the decomposition of martensite and resist tempering softening. In addition, carbide-forming elements also play a very significant role in delaying tempering softening. Although cobalt and silicon are non-carbide-forming elements, they have a strong retarding effect on the movement and growth of cementite nuclei. Therefore, they also have the effect of delaying tempering softening.

Performance characteristics of wear-resistant alloy steel:

(1) Although ordinary low-alloy structural steel is a low-carbon (C < 0.20%) and low-alloy (total alloy element content < 3%) steel, due to the strengthening effect of alloying elements, compared with carbon structural steel with the same carbon content, this steel has higher strength (especially yield point) and good plasticity, toughness, corrosion resistance, and weldability.

(2) Stainless steel is a general term for stainless steel and acid-resistant steel that are resistant to atmospheric, acid, alkali, and salt corrosion. Generally speaking, steel that can resist corrosion in the atmosphere is called stainless steel. Steel that can resist corrosion in strongly corrosive media is called acid-resistant steel.