Preheating of Martensitic Stainless Steels

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Martensitic Stainless Steels. The martensitic stainless steels are hardenable by heat treatment and are magnetic. The low-carbon type can be welded without special precautions. The types with over 0.15% carbon tend to be air hardenable and, therefore, preheat and postheat of weldments are required. A preheat temperature range of 230-290°C is recommended. Postheating should immediately follow welding and be in the range of 650-760°C, followed by slow cooling.
If preheat and postheat are not possible, an austenitic stainless steel filler metal should be used. Type 416Se is the free-machining composition and should not be welded. Welding processes that tend to increase carbon pickup are not recommended. Increased carbon content increases crack sensitivity in the weld area.
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