After welding requirements T91 cooled to below the Ms point and maintain a certain period of time before tempering Shanghai t91 alloy tube, after welding, the cooling rate of 80 ~ 100 ℃ / h. If without insulation, austenite joints may not be completely transformed t91 steel, tempering heating will lead to the precipitation of carbides along austenite grain boundaries import t91 alloy tube, such an organization is very brittle. But after welding T91 does not allow to cool to room temperature and then tempered, because of its welded joints have cooled dangerous cold cracking when the room temperature. For T91, the best starting temperature of 100 ~ 150 ℃, and the insulation 1h t91, can basically ensure organizational change is completed. T91 weld tempering holding time of not less than 1 h, in order to ensure their organization is completely transformed into tempered martensite. In order to reduce the residual stress T91 steel welded joints, must control its cooling rate is less than 5 ℃ / min. T91 steel welding process is illustrated in Figure 3 shows. ① preheated 200 ~ 250 ℃; ② between welding, surface temperature 200 ~ 300 ℃; ③ After welding cooling rate of 80 ~ 100 ℃ / h; ④100 ~ 150 ℃ incubated 1 h; ⑤730 ~ 780 ℃ tempering 1 h; ⑥ not more than 5 ℃ / min cooling rate of domestic t91 alloy tube steel _ Yancheng t91_ Katherine source provided by the 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!