The structure and properties of 0Cr32Ni7Mo4N duplex stainless steel after different deformation process.

31/mag/2018 03:12:00 stainless steel Contatta l'autore

Bipolar organization composed of ferrite  17-4 PH Stainless Steel Bar at room temperature (alpha) and austenite (gamma phase) two phase composition, with excellent mechanical properties and corrosion resistance, widely used in petroleum, chemical industry, port, ocean engineering and other fields. With the development of drilling technology, drilling in deep put forward higher request to the use of materials, Sweden Sandvik company developed SAF3207 HD seamless tube, used to connect to the surface of the control platform and ofd submarine umbilical cord, can further reduce the wall thickness and weight, the umbilical cord and under high pressure in the deep instead of SAF2507 of use, make it possible to oilfield exploitation of deep sea floor.

Duplex stainless steel hot working performance is poorer, greatly restricted its application, especially like SAF3207 HD high grade steel, hot working, particularly prominent problems, in recent years, scholars at home and abroad to do a lot of basic research on mechanism of duplex stainless steel thermoplastic, is generally believed that alpha and gamma two-phase strength differences and dynamic response mechanism is the main cause of the difference of thermoplastic, two corresponding become incongruity causes of crack formation and expansion in the alpha/gamma phase boundary, but there is no effective way to solve the difference of duplex stainless steel thermoplastic, study of SAF3207 HD steel is rarely reported.

Company technical personnel to 0 cr32ni7mo4n experimental steel as the research object, self smelting ingot casting, hot rolling after cold rolling and the solid solution treatment after cold rolling experiment directly, contrast different forming process at room temperature and plastic deformation ability of the preparation of sample, test of steel plate mechanical properties and corrosion resistance, and analyze the effect of processing technology on the properties of 0 cr32ni7mo4n to study the feasibility of high grade of duplex  15-5 PH Stainless Steel Bar cold rolled directly. The results show that:

(1) when the plastic deformation at room temperature is at room temperature, there is a dislocation cell structure in the multi-line slip formation, and the main deformation mechanism is the single system slip and mechanical twin, and the deformation degree is larger than that of the latter after cold rolling.

(2) 0Cr32Ni7Mo4N experimental steel thermal processing is poor, and the insulation of the furnace is still cracking when hot rolling. As-cast billet after 1100 ℃ solid solution treatment, direct cold rolling, pressure rate was 80%, steel plate edge is flat defects, cold forming performance is good.

(3) the as-cast 1100 ℃ after solid solution directly cold-rolled steel plate test, after 1140 ℃ heat treatment 3 min, homogeneity, small grains, exudates few in number, the tensile strength of 1082.9 MPa, the elongation is 29.3%, less than 36 HRC surface hardness, meet the ASTM A789 standards.

(4) 0 cr32ni7mo4n experiment the forming process of the best route of steel, cast steel billet after 1100 ℃ solid solution treatment, eliminate the sigma phase and even tiny gamma grain; After the pickling process, multipass cold rolling is carried out, and the deformation amount is more than 80%. Cold rolled at 1140 ℃ after heat treatment to obtain uniform organization, make the mechanical properties and corrosion resistance of good cooperation.

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