Welding thermal cycle grown grains have a significant impact on the heat-affected zone of welded joints, especially close to the heating temperature is the highest fusion zone. When the cooling rate is small, in the HAZ will appear coarse massive ferrite and carbides tissue import t91 alloy tube, the plastic steel decreased; the cooling rate is large, due to the generation of coarse martensite also make plastic welded joints decreased. T91 in Shanghai before PWHT t91 alloy tube, cooling temperature is not lower than 100 ℃ Tianjin t91 alloy tube, if cooling at room temperature and the environment and more humid, the prone to stress corrosion cracking. In Germany: Before post weld heat treatment must be cooled to below 150 ℃. In the thicker workpiece, and the presence of fillet has geometry bad circumstances, the cooling temperature is not lower than 100 ℃. If the cooling at room temperature, non-humid, or prone to stress corrosion cracking domestic t91 alloy tube, Yangquan 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!