A welding wire for 9cr-3w-3co martensitic heat-resistant steel and its application in gtaw welding process

Abstract

The invention provides a welding wire for 9Cr-3W-3Co martensitic heat-resistant steel and its application in GTAW welding process. In terms of mass percentage, the chemical composition of the welding wire is: C: 0.05-0.12%, Si: 0.50% or less, Mn: 1.0% or less, P: 0.01% or less, S: 0.008% or less, Ni: 0.20% or less, Cr: 8.50-9.50%, W: 2.50-3.0%, Co: 2.50-3.50%, Nb: 0.03-0.07%, V: 0.15-0.25%, N: 0.03-0.07%, B: 0.004% or less, Cu: 0.10% Below, Ti: 0.01% or less, Al: 0.03% or less, and the rest are Fe and unavoidable impurities. The A of the welding wire GTAW weld metal C1 High point, high impact toughness of weld and excellent high temperature creep strength.

Description

technical field [0001] The invention belongs to the technical field of welding materials, and in particular relates to a welding wire for 9Cr-3W-3Co martensitic heat-resistant steel and its application in a GTAW welding process. Background technique [0002] 9Cr-3W-3Co series martensitic heat-resistant steel is an ideal material for the construction of ultra-supercritical thermal power units with steam temperature parameters above 625°C. The commercial grades include G115 steel developed in China and T / P93 steel developed in Japan. The creep endurance strength is 20%-50% higher than that of T / P92 steel. The main difference between G115 steel and T / P93 steel is that the former adds about 1% Cu element. In the process of building high-parameter ultra-supercritical thermal power units, there are a large number of welded joints of this type of steel, so it is necessary to meet the requirements of process performance and mechanical properties of joints at room temperature, espec...

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Problems solved by technology

Patent Publication No. CN108838579A "A Bright Welding Wire for Ultra-Supercritical Coal-fired Power Station Heat-resistant Steel". Although the welding wire does not contain Cu element, the weld seam has obtained high impact toughness, but its C element content is too high. Increased welding crack sensitivity, in addition, its W element content is significantly lower than that of the base metal, which will reduce the high temperature creep durability strength

In addition, most of the above-mentioned patent documents adopt the composition design of high B and low N. Due to the limitation of the welding metallurgical process, it is difficult for these welding wires to obtain a weld with high B and low N composition combination under the conventional GTAW welding process. It is extremely wasteful, and may increase the sensitivity of the weld to microscopic defects, and is not conducive to the high-temperature durable creep strength of the weld

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