Alloy 410S (UNS S41008) is a low carbon, non–hardening modification of Alloy 410 (UNS S41000) the general purpose 12% chromium martensitic stainless steel. The low carbon and a small alloy addition minimize austenite formation at high temperatures which restricts the alloys ability to harden.
Petroleum Refining and Petrochemical Processing
ASTM: A 240
ASME: SA 240
The alloy can not be hardened by heat treatment. It is annealed between 1600 – 1650°F (871 – 899°C), and then air cooled to relieve cold working stresses. 410S should not be exposed to temperatures above 2000°F (1093°C), due to embrittlement. If large grains are found after annealing mildly cold-worked material, the annealing temperature should be decreased to 1200 – 1350°F (649 – 732°C).
410S is generally considered to be weldable by the common fusion and resistance techniques. Special attention should be given to avoid brittle weld fractures during fabrication; this includes minimizing discontinuities, maintaining low weld heat input, and occasionally warming the part somewhat before forming. 410S is generally considered to have slightly poorer weldability than the most common ferritic stainless steel grade 409. A major difference can be attributed to the addition of alloy, to control hardening which results in the need for higher heat input during welding.