As can be seen, T91 low critical cooling rate, the austenite stability of large, less prone to the normal cooling pearlite transformation, which occurs when cooled to a lower temperature martensitic transformation. Because of this, T91 hardened and cold cracking tendency great. Since the heat-affected zone of a variety of tissues have different densities, different expansion coefficients and lattice forms t91 steel, in the heating and cooling process is bound with different volumetric expansion and contraction; on the other hand, since the welding heat has not uniformity and high temperature characteristics, and therefore a lot of internal stress of welded joints T91. For T91, very stable austenite, to cool to a lower temperature (about 400 ℃) to become martensite. Coarse martensite brittle and hard, but in the joints under complex stress state. At the same time, the hydrogen cooling process to weld seam zone near the weld diffusion, the presence of hydrogen embrittlement prompted the martensite, the result of their combined effects, it is prone to cold cracking in the hardened area. Sales of the company consists of about a dozen series pipe, high pressure boiler pipe large diameter thick wall pipe seamless steel pipe can be divided into ordinary steel and alloy steel pipe points, divided into high-pressure steel pipe steel pipe and high temperature resistance hydrogen sulphide pipes, steel pipes are mainly used in machining processing machinery bracket Baosteel t91 alloy tube, mechanical parts face specific requirements are not very high. Early menacing northern China haze let suffered another "cardiopulmonary the suffering," the ministry criticized China Hebei cities haze emergency form than content. To this end import t91 alloy tube, the ministry started in 2014 on the 15th winter air pollution control inspection work, and occasionally send drones supervision, direct exposure. Yongqing environmental protection (33.720, 0.07, 0.21%), Longking (29.66, 1.05, 3.67%), State Power, fresh (22.29, 0.21, 0.95%), Colin Green (27.02, 0.47, 1.77%) and trimer environmental protection (27.130, 0.00, 0.00%) expected to benefit. Shanghai t91 alloy steel pipe _ Katherine source (certified) _ Shanwei t91 provided by source Pipe Co., Ltd. Liaocheng trillion. Liaocheng Katherine source Pipe Co., Ltd. (www.lczygg.com) Shandong Liaocheng, steel leader, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. Katherine source leader in steel with the staff warmly welcome all inquiries negotiations to create Katherine source steel a better future.