Phase proportion control method for surfacing welding of two-phase corrosion resistant layer on surface of carbon steel

Abstract

The invention discloses a phase proportion control method for surfacing welding of a two-phase corrosion resistant layer on the surface of carbon steel. The phase proportion control method comprises the following specific steps that a transition isolation layer, a filling layer and a cover layer are sequentially arranged on a base material through surfacing welding; the high-nickel ultra-low carbon austenitic deposited metal is adopted as the transition isolation layer; high-chromium and high-nickel stainless steel electrode is adopted for large-current and high-efficiency arc surfacing welding to form the filling layer, namely the super alloyed anti-corrosion surfacing welding layer of an austenite-ferrite double-phase structure; the interlayer temperature is controlled to be 120 DEG C orlower in the process of surfacing welding; small-current gas shielded tungsten arc welding is adopted for cover surface surfacing welding to form the cover layer; the post weld heat treatment is notneeded after surfacing welding is finished; and the penetrant inspection is carried out 24 hours after welding, and the ferrite content is measured through a ferrite tester. According to the weldingmethod, two-phase structure corrosion-resistant surfacing welding layer with approximately equal proportion can be formed, and heat treatment is not needed after welding so that the machining technology can be simplified, and the manufacturing cost can be reduced.

Description

technical field [0001] The invention relates to a method for controlling the phase proportion of a two-phase corrosion-resistant layer for overlay welding on a carbon steel surface, and belongs to the technical field of welding processing of chemical equipment. Background technique [0002] Duplex stainless steel composed of austenite and ferrite has more beneficial corrosion resistance than single-phase austenitic stainless steel, and its structure has an equal proportion of ferrite + austenite duplex structure, so it has both characteristics of phase organization. Due to the existence of ferrite, the yield strength of duplex stainless steel is about twice that of ordinary austenitic stainless steel, and the existence of austenite ensures its good plasticity and toughness. In terms of stress corrosion resistance, duplex stainless steel has a significant advantage over austenitic stainless steel. In the manufacture of chemical equipment, the surface of cost-effective carbo...

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Problems solved by technology

According to the Cr-Ni binary phase diagram, when the contents of Cr and Ni are 22% and 5% respectively, an approximately equal proportion austenite + ferrite duplex structure can be formed in an equilibrium state, but the actual surfacing process Heating is a non-equilibrium thermal process, and its microstructure transformation kinetics is far away from the equilibrium state, so it is often difficult to obtain an equal proportion of austenite + ferrite duplex structure

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