Corrosion resistant alloy steel castings heat treatment process

Corrosion resistant steel alloy castings include corrosion resistant cast steel, corrosion resistant cast iron two categories. The specific heat treatment process:

The first, Corrosion cast

Martensitic corrosion steel: w (C) of such steel in the range of 0.10-0.45%, and w (Cr) in the 12.0-14.0%. The main heat-treated to prevent: 1) quenched and tempered. Mainly in order to obtain martensite and prevent carbide precipitation; quenched and tempered to eliminate quenching stress and improve toughness. 2) normalizing + tempering. Low-carbon martensitic corrosion resistant steels containing a small amount of nickel, molybdenum, silicon and other elements, after normalizing + tempering, improve the mechanical properties.

Ferrite corrosion resistant steel: this kind of steel w (C) or less 0.12%, w (Cr) for 15-20%. The main heat treatment ways: 1) the as-cast; 2) annealing. Annealing temperature should not be less than 540 ℃, and do not higher than 850 ℃. Heating process, when the temperature reaches 350 ℃, the last a period of time soaking, lest produce large casting stress.

Austenitic corrosion resistant steel: a typical type of steel is 1 cr18ni9ti. The main heat treatment ways: 1) solution. The casting heated to 950-1175 ℃, the heating of the low temperature preheating first, then rapid heating the solution temperature process. 2) solution + stabilizing treatment. To the other containing titanium niobium alloy elements such as casting solution treatment, should be further stabilizing treatment. That is to reorganize the casting heated to 850-930 ℃, then rapid cooling. To prevent chromium carbide precipitation, improve the grain boundary corrosion resistance performance.

Precipitation hardening corrosion resistant steel: a typical type of steel is ZGCr17Ni4Cu2. Heat treatment for solid solution and aging strengthening, solid solution temperature is 1020-1060 ℃, and age hardening temperature for 560-650 ℃.

The second, the corrosion resistance of cast iron

Corrosion resistance of cast iron containing high silicon, aluminum, chromium, nickel and other single element or by their blend of composite element. In order to improve comprehensive mechanical properties, often join copper, such as rare earth alloy elements, this kind of material belong to a hard brittle material corrosion resistance. Heat treatment for stress relief annealing.