Welding process for stainless steel pipe fitting

Abstract

The invention discloses a welding process for a stainless steel pipe fitting. The welding process comprises the following steps of S1, manufacturing a threaded part; S2, extruding a molded part, specifically, processing a thin-wall pipe by virtue of an extrusion molding machine to form the molded part with one closed end; S3, preheating, specifically, heating the threaded part and the molded partto 500 DEG C through a heater; S4, performing vacuum sealing, specifically, clamping the threaded part at a rotating end of a welding machine, clamping the molded part at a moving end of the welding machine, forming a sealed space by means of a housing, and vacummizing the sealed space; S5, performing friction welding, specifically, driving the threaded part by a motor to rotate at a high speed, meanwhile, enabling the molded part to gradually get close to the threaded part under the action of axial force of an oil cylinder piston, and after the threaded part makes contact with the molded partand is pressed tightly, maintaining the state for 6s; and S6, upsetting, specifically, performing braking, enabling the axial force to rapidly increase to the set upsetting pressure of 3.0-4.0MPa / mm2for upsetting, and the upsetting pressure maintaining time is 1-5 seconds. By means of cooperation of friction welding, preheating and vacuum welding, high-quality welding of the stainless steel pipefitting is achieved.

Description

technical field [0001] The present invention relates to the processing of stainless steel pipes, more particularly, it relates to a welding process for stainless steel pipe fittings. Background technique [0002] The existing welded stainless steel compression fittings are all welded by argon arc welding. Zhou Xiayu and Zhao Lijun introduced a forming process of three-way thin-wall stainless steel compression pipe fittings in the article "Forming Technology of Stainless Steel Compression Fittings" in the sixth issue of 2003 in "Metal Forming Technology", including: blanking-extrusion Tees - Cut Caps, Plain Ends - End Forming - Welding - Weld Seams and Finishes. [0003] The welding adopts argon arc welding without adding wire. The basic process is to first align the two mouths that need to be welded to the parts, and spot weld two points in the 180°circumferential direction at the joint of the outer diameter to combine the two parts together. Then clamp the outlet part an...

AI Technical Summary

Problems solved by technology

After the action of welding heat cycle, the heat-affected zone at the peak temperature of 600-1000 °C is the sensitized zone of the welded joint. Due to the precipitation of carbide Cr23C6 along the grain boundary, under the action of the corrosive medium, it is easy to produce the intergranular area of ​​the sensitized zone. Corrosion, so it cannot be used in harsh environments or where corrosive liquids are transported

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