ER90S-B3 description: 90S-B3 is used to weld such alloys as 2 1/4% Cr-1% Mo steels, which are found in high temperature and high pressure piping and vessels. May also be used on carbon steels to Cr-Mo steels but should always have careful control of preheat, inter-pass and post-heat to avoid cracking. Use with a pre-heat and inter-pass temperature of 375°f minimum.