Medium temperature thick-wall WB36/1Cr18Ni9Ti dissimilar steel welding technology

Abstract

The invention discloses an intermediate temperature thick wall WB36 / 1Cr18Ni9Ti heterogenous steel welding technique relating to a pearlite(P) / austenite (A) welding technique. The A technique of the invention includes: {1}buttering three layers first at a WB36 steel side by A307 welding rod as an insulating layer; not preheating when welding and carrying through dehydrogenation treatment after welding; a Phi 3.2mm welding rod must be adopted when buttering a first layer to carry through small current welding with a current range of 70 to 90A for reducing dilution on the welding rod; {2} polishing the surface of the buttering layers to 8mm to form a WB36 / 1Cr18Ni9Ti butt joint form according with the requirement of criterion; {3} using the A307 or A 137 welding rod to fill and the diameter of the welding rod is Phi 3.2mm or Phi 4.0mm; {4} canceling the heat treatment after welding. The invention reduces the manufacture cost and improves the manufacture efficiency simultaneously when ensuring and improving the joint quality of welding. The invention is suitable for intermediate temperature thick wall WB36 / 1Cr18Ni9Ti heterogenous steel welding.

Description

Technical field [0001] The invention relates to a pearlite (P) / austenite (A) dissimilar steel welding process, in particular to a welding process for a thick-walled WB36 / 1Cr18Ni9Ti dissimilar steel joint working under medium temperature conditions. Background technique [0002] In recent years, with the development of my country's economy, the demand for electricity has soared, and more and more supercritical units and ultra-supercritical units have been built. A large number of thick-walled austenite / pearlite (A / P) dissimilar steels that work under medium temperature (200~400℃) have appeared in the unit. For example, the main water supply pipeline of the unit uses low-alloy pearlite WB36 steel. , The material of the flow orifice is 1Cr18Ni9Ti austenitic stainless steel, which causes the welding problem of large diameter and thick wall A / P dissimilar steel. Compared with the small diameter pipe A / P dissimilar steel joints that work at high temperatures, this type of joint not onl...

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Problems solved by technology

Compared with the small-diameter pipe A / P dissimilar steel joints working at high temperature, this type of joint not only increases in size, but also has significantly different operating conditions. Therefore, although the small-diameter pipe A / P dissimilar steel welding process is relatively mature (such as the current People's Republic of China Electric Power Industry Standard DL / T752-2001 "Technical Regulations for Welding of Dissimilar Steels in Thermal Power Plants"), but they are not suitable for welding large-diameter pipe thick-walled A / P dissimilar steel joints at medium temperature

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