Stainless steel----highly alloyed austenitic stainless steel 310S (S31008)/ EN 1.4845
Introduction: SS310 is a highly alloyed austenitic stainless steel designed for elevated-temperature service. The high Cr and Ni contents enable this alloy to resist oxidation in continuous service at temperatures up to 1200°C provided reducing sulfur gases are not present. In intermittent service it can be used at temperatures up to 1030°C as it resists scaling and has a relatively low coefficient of expansion. This alloy has superior resistance to both SS304 and SS309 in carburizing and reducing environments.
SS310 types are used for their high-temperature oxidation resistance for applications such as furnace parts, mufflers, radiant tubes, ammonia converters, etc.
Product Range:
Product is available in Cold Rolled, Continuous Mill Plate and Plate Mill Plate form up to 60" wide in various thicknesses.
For inquiry about minimum quantity, specific thickness and tolerances.
Certification: ASTM A240, A480, A666, ASME SA240, SA480, SA666, ASTM A262, EN 10088-2, EN 10028-7.
Thermal Processing & Fabrication Annealing
Annealing is achieved by heating to between 1030°C and 1150°C for 90 minutes per 25mm thickness followed by water quenching. Annealing will ensure that any carbide precipitates are taken back into solution.
Cold Working
SS310 can be deep drawn, stamped, headed and upset without difficulty. Since SS310 work hardens, severe forming operations should be followed by annealing.
Hot Working
SS310 can be forged, hot headed and upset satisfactorily. Uniform heating of the steel in the range of 1150°C and 1250°C is required. The finishing temperatures should not be below 950°C. Forgings should be cooled rapidly in air or water. As precipitation of carbides can be harmful in corrosive environments, SS310S is recommended.
Welding
SS310 can be satisfactorily welded and brazed by all methods, giving a tough weld. SS310S should be specified if carbide precipitation can have a detrimental effect on the performance of the steel under operating conditions.
Welding procedures for SS310 will have to be selected with care in order to avoid hot cracking due to the fully austenitic weld microstructure obtained from using matching filler metals.
Oxidation
In many processes, isothermal (constant temperature) conditions are not maintained and process temperatures vary. Expansion differences between the base metal and the scale during heating and cooling can cause cracking and spalling of the protective scale.
This allows the oxidizing media to attack the exposed metal surface. The spalling resistance is greatly improved with the higher nickel content of SS310 because nickel reduces the expansion differential between the scale and the base metal.
Corrosion Resistance
Because of the many possible variations involved—temperature, corrosive environment, alloy composition, time, operating practice, etc.—it is difficult to discuss every combination in detail. Thus, the following data should be used as a guideline.
Effect of atmosphere
An increase in corrosion rate can be expected in the presence of water vapor for the traditional 18/8 type stainless steels. The increased nickel and chromium contents of SS310 provide good resistance to moist air at temperatures in excess of 980°C.
Flug Gases
It is extremely difficult to generalize corrosion rates in flue and process gases since gas composition and temperature may vary considerably within the same process unit.
Combustion gases normally contain sulfur compounds, as sulfur dioxide is present as an oxidizing gas, along with carbon dioxide, nitrogen, carbon monoxide and excess oxygen. Protective oxides are generally formed and, depending on exact conditions, the corrosion rate may be similar or slightly greater than for service in air.
Reducing flue gases contain varying amounts of hydrogen sulfide, hydrogen, carbon monoxide, carbon dioxide and nitrogen. The corrosion rates encountered in these environments are sensitive to hydrogen sulfide content and temperature, and satisfactory material selection often necessitates service testing. The high nickel content of SS310 may be deleterious in some instances due to sulfidation, in which case SS309 may be the preferred material.
Carburisation
High chromium and nickel contents result in a slower diffusion rate of carbon into the steel. SS310 therefore has good resistance to carburizing atmospheres.
Ammonia and Nitrogen
The high nickel content of CS310 ensures a good resistance to ammonia atmospheres at high temperatures. Typical corrosion rates for SS310 in an ammonia converter containing 5-6% NH3 after 30,000 hours at 500°C, are in the region of 0.003mm/yr.