Therma 4910

Austenitic creep resisting grade with good resistance to stress relaxation cracking. Therma 4910 belongs to the austenitic chromium-nickel-molybdenum stainless steel grades. A specific feature for Therma 4910 grade is high creep resistance as a result of nitrogen and boron alloying, which makes this grade suitable for use in high temperatures. The low carbon content is unusual in creep resisting steels and together with absence of strong carbide forming elements such as titanium and niobium, carbide precipitation leading to stress relaxation cracking is minimized.

A common feature of Outokumpu high temperature steels is that they are designed primarily for use at temperatures exceeding ~550 °C, i.e. in the temperature range where creep strength as a rule is the dimensioning factor and where HT corrosion occurs. Therma 4910 is intended for use up to about 800°C. Optimising steels for high temperatures has meant that their resistance to aqueous corrosion has been limited. All steels are austenitic, resulting in relatively high creep strength values.

Characteristic properties:

• Good resistance to oxidation, suitable for use up to about 800 °C
• Good resistance to high-temperature corrosion
• Excellent mechanical strength at elevated temperatures
• Resistance to stress relaxation cracking, useful especially in the heat affected zone of weldments
• Although not intended for wet corrosion applications,  the presence of molybdenum and nitrogen is beneficial for pitting  corrosion resistance in chloride environments