S32750 Round Bar Sheet Cutting Parts High Temperature Resistant Custom Stainless

Product Specification

S32750 round bar sheet cutting parts high temperature resistant custom stainless steel alloy.

‌S32750 is a super duplex stainless steel with excellent corrosion resistance and high strength for harsh environments. ‌It is mainly used in marine engineering, chemical processing, oil and gas extraction and other fields. The tensile strength and corrosion resistance of S32750 make it perform well in these fields and become the preferred material for these applications. In addition, S32750 is also used in industries such as oil refining, fertilizers, papermaking, petroleum and chemicals. ‌

Chemical Composition
The chemical composition of S32750 stainless steel includes:

Chromium (Cr): 22.0%～26.0%
Nickel (Ni): 6.0%～8.0%
Molybdenum (Mo): 3.0%～4.5%
Nitrogen (N): 0.20%～0.35%
Iron (Fe): Balance

Other elements such as carbon (C), silicon (Si), phosphorus (P), sulfur (S), etc. also have specific content limits.

Physical properties

Density: 8.03 g/cm³
Melting point: 1300-1390 ℃

1. The phase ratio needs to be controlled. The most suitable ratio is that the ferrite phase and the austenite phase each account for about half, and the amount of one phase cannot exceed 65% at most, so as to ensure the best comprehensive performance. If the two-phase ratio is unbalanced, for example, the amount of ferrite phase is too much, it is easy to form single-phase ferrite in the welding HAZ, which is sensitive to stress corrosion cracking in certain media.
2. It is necessary to master the organizational transformation law of duplex stainless steel and be familiar with the TTT and CCT transformation curves of each steel grade. This is the key to correctly guide the formulation of duplex stainless steel heat treatment, hot forming and other processes. The precipitation of brittle phases in duplex stainless steel is much more sensitive than austenitic stainless steel.
3. The continuous use temperature range of duplex stainless steel is -50 to 250℃. The lower limit depends on the brittle transition temperature of the steel, and the upper limit is limited by the brittleness of 475℃. The upper limit temperature cannot exceed 300℃.
4. Duplex stainless steel needs to be cooled quickly after solution treatment. Slow cooling will cause the precipitation of brittle phases, resulting in a decrease in the toughness of the steel, especially the resistance to local corrosion.
5. The lower limit temperature of hot processing and hot forming of high chromium-molybdenum duplex stainless steel cannot be lower than 950℃, super duplex stainless steel cannot be lower than 980℃, and low chromium-molybdenum duplex stainless steel cannot be lower than 900℃, to avoid surface cracks caused by the precipitation of brittle phases during processing.
6. The 650-800℃ stress relief treatment commonly used for austenitic stainless steel cannot be used, and solid solution annealing treatment is generally used. When the overall stress relief treatment of 600-650℃ is required after duplex stainless steel is surfacing on the surface of low alloy steel, the toughness and corrosion resistance caused by the precipitation of brittle phases, especially the decline in local corrosion resistance, must be considered, and the heating time within this temperature range should be shortened as much as possible. The heat treatment of low alloy steel and duplex stainless steel composite plates should also be considered in the same way.
7. It is necessary to be familiar with the welding rules of duplex stainless steel, and the welding of austenitic stainless steel cannot be applied to all of them. Whether the equipment of duplex stainless steel can be used safely is closely related to the correct mastery of the welding process of steel. The failure of some equipment is often related to welding. The key lies in the control of line energy and interlayer temperature, and the correct selection of welding materials is also very important. The two-phase ratio of the welded joint (weld metal and welded HAZ), especially the necessary amount of austenite in the welded HAZ, is very important to ensure that the welded joint has the same performance as the parent material.
8. When selecting duplex stainless steel in different corrosive environments, it should be noted that the corrosion resistance of steel is always relative. Although duplex stainless steel has good local corrosion resistance, for a certain duplex stainless steel, it also has an applicable medium condition range, including temperature, pressure, medium concentration, pH value, etc., which needs to be carefully selected. Many of the data obtained from literature and manuals are laboratory corrosion test results, which often differ from the actual conditions of the project. Therefore, attention should be paid when selecting materials. If necessary, corrosion tests in actual media or coupon tests under field conditions, or even tests of simulated devices, need to be carried out.