DAIKOFCW 5CrMo

5%Cr-½%Mo steel for elevated temperature service up to 600°C.

In the PWHT condition the microstructure consists of tempered bainite.

EN W.Nr.: 12CrMo 19 5 (1.7362), X7CrMo 6 1 (1.7373), X11CrMo 6 1 (1.7374), GS-12CrMo 19 5 (1.7363).
ASTM: A387 gr. 5, A335 gr. P5, P5b, A234 gr. WP5 (fittings), A199 gr. T5, A213 gr. T5, T5b, A182 gr. F5, F5a, A336 gr. F5, A217 gr. C5.

Due to the inherent hardness observed in the as-deposited state, reaching values of up to 400HV, coupled with the relatively diminished fracture resistance characteristic of the 5CrMo bainitic microstructure, it is recommended to employ a preheat and maintain a minimum interpass temperature of 200°C. This measure is essential to prevent the occurrence of hydrogen-induced cold cracking. Ensuring electrodes are meticulously controlled and handled is crucial to achieve weld metal with hydrogen levels below 5ml/100g. In instances involving TIG root runs or all-TIG welds, consideration may be given to a lower preheat of 150°C. However, it should be acknowledged that opting for faster cooling rates in such scenarios may result in deposits that are partially martensitic and harder in nature. The complete transformation of the 5CrMo during welding occurs within a working range of 200-350°C. Consequently, direct transfer (at temperatures exceeding 150°C) to Post-Weld Heat Treatment (PWHT) is permissible, followed by Non-Destructive Examination (NDE). If PWHT is intended after complete cool-out and NDE, it is advisable to maintain the preheat temperature for a specified duration post-welding, in accordance with thickness, to facilitate effective hydrogen dispersal. Notably, this precaution holds less significance for TIG and solid wire MAG processes. PWHT to temper the weldment typically falls within the range of 705-760°C, aligning with ASME B31.3 standards. The minimum recommended holding time for this process is two hours. For castings, the suggested minimum PWHT temperature is lower, with specified temperatures as low as 670°C.