Ferritic chrome steels are heat sensitive. Therefore the steel 1.4749 should be welded with lowest possible heat input by using thin electrode diameter, low current intensity and stringer bead welding. For wall thicknesses under 3mm, it is not necessary to preheat 1.4749. For thicker construction parts (> 3mm) the preheating and interpass temperatures 200 - 300°C should not be under respectively over run. 1.4749 can be processed with similar or higher alloyed filler metals. With sulphurous atmospheres a ferritic top layer should be laid on the media side (Thermanit L 1.4820).
Cold Forming
When cold forming 1.4749, certain preventative measures should be observed. Sheets up to 3mm thickness can be cold bent if necessary preheating with 200 - 300°C should be done. Products with thicknesses > 3mm must be preheated up to 600 - 800°C, concerning machinability 1.4749 can be compared to a low carbon steel.
Embrittlement
While heating 1.4749 over about 950°C embrittlement by grain growth occurs, which cant be removed anymore. A further embrittlement occurs in the temperature range between 400 and 550°C (475°C embrittlement). A longer abidance within this temperature range should be avoided. This loss of ductility can be corrected by a short heating up to 700 to 800°C. In the temperature range of 600 to 900°C 1.4749 has the affinity to signma-phase-embrittlement, so that after longer application within this temperature range the ductile values are strongly reduced. The steel should not come into operation within this temperature range, if mechanical stress is existent.
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