New metallurgical technology
|Corrosion resistant steel alloy castings include corrosion resistant cast steel and corrosion resistant cast iron. The specific process is: martensitic corrosion resistant steel, such steel has w(C) between 0.10-0.45% and w(Cr) between 12.0-14.0%.|
Corrosion resistant steel alloy castings main heat treatment prevents:
- 1) Quenching and tempering treatment. Mainly to obtain martensite and prevent carbide precipitation; quenching and tempering is to eliminate quenching stress and improve toughness.
- 2) Normalizing + tempering. Low-carbon martensitic corrosion-resistant steel containing a small amount of nickel, molybdenum, silicon and other elements, after normalizing + tempering treatment, the mechanical properties are improved.
Ferritic corrosion resistant steel, this type of steel has w(C) ≤ 0.12% and w (Cr) between 15-20%. Main heat treatment methods:
- 1) as-cast;
- 2) Annealing. The annealing temperature should not be lower than 540 ° C, nor higher than 850 ° C.
During the heating process, when the temperature reaches 350 ° C, the final heat is applied for a period of time to avoid large stress on the casting.
Austenitic corrosion resistant steel, the typical steel grade is 1Cr18Ni9Ti. Main heat treatment methods:
- 1) Solid solution. The casting is heated to 950-1175 ° C, and it is preferable to adopt a process of preheating at a low temperature and then rapidly heating to a solution temperature.
- 2) Solid solution + stabilization treatment. After solid solution treatment of an alloy element such as titanium bismuth, it should be further stabilized. That is, the casting is reheated to 850-930 ° C and then quickly cooled. In order to prevent the precipitation of chromium carbide, improve the resistance to intergranular corrosion.
Precipitation hardening corrosion resistant steel, the typical steel grade is ZGCr17Ni4Cu2. The heat treatment method is solid solution + aging strengthening, the solution temperature is 1020-1060 ° C, and the age hardening temperature is 560-650 ° C.
Corrosion-resistant cast iron, corrosion-resistant cast iron contains a single element such as silicon, aluminum, chromium, nickel or a composite element composed of them. In order to improve the comprehensive mechanical properties, alloying elements such as copper and rare earth are often added, and such materials are relatively hard and corrosion resistant materials. The heat treatment method is to eliminate internal stress and low temperature annealing.
Link to this article： Metallurgical technology of corrosion resistant steel alloy castings
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