Ms point T91 steel is about 400 ℃ Shanghai t91 alloy tube, preheat temperature is generally selected in the 200 ~ 250 ℃. Preheat temperature is not too high, otherwise the cooling rate lower joints may cause grain boundary carbide precipitation and the formation of ferrite in the weld joint, thereby greatly reducing the steel welded joints at room temperature impact toughness. Preheating temperature limit from Harbin Boiler Works have done a good description of available plug test. T91 steel cold cracking tend to be larger, under certain conditions, prone to delayed cracking, it must be tempered welded joints within 24 h after welding. T91 weld tissue state of lath martensite, tempered martensite after tempering can be changed, and its performance is superior than the lath martensite. Tempering temperature is low t91, t91 tempering effect is not obvious import alloy pipe, weld metal is easy to aging and embrittlement; tempering temperature is too high (more than AC1 line), the joint may also austenitizing again, and in the subsequent The cooling process re-hardened. At the same time, as described in the foregoing, the tempering temperature should also be considered to determine the impact of the joint softening layer. Generally, T91 tempering temperature is 730 ~ 780 ℃ Shanghai t91 alloy tube | Pingxiang t91 | Katherine source of steel provided by source Pipe Co., Ltd. Liaocheng trillion. Liaocheng Katherine source Pipe Co., Ltd. (www.lczygg.com) strong, credible, Liaocheng in Shandong steel industry has accumulated a large number of loyal customers. The company better work attitude and constantly improving Katherine source of innovative ideas will lead pipe and you work into the brilliant, for a better future!