Method for welding martensite heat-resistant steel

Abstract

The invention relates to a method for welding martensite heat-resistant steel, and belongs to the field of high-parameter container manufacturing. For solving the problems that the closed seam weldingconstruction of the high-parameter container martensite heat-resistant steel used in a secondary reheating unit is prone to occur the conditions of crack defect, post-welding low hardness and the like, the method comprises the following steps that 1, a welding groove is machined; 2, pre-welding predation is performed; 3, pre-welding is preheated; 4, argon is filled; and 5, welding is performed; if a barrel body is too large, a weld joint is too long, an interlayer temperature is difficult to control, and then a flame heating temperature compensator is adopted to heated in a following mode soas to compensate for temperature loss, if the volume of the barrel body is too large, root oxidation cannot be prevented by establishing a large-scale closed gas protection chamber, and then a specialargon gas protection device is adopted for protection; and in the welding process of the high-alloy steel thick-wall container barrel body, the welding joint is heated in a flame preheating mode, thechange condition of the temperature is difficult to continuously measure, and a temperature monitoring device is arranged at the front end of the to-be-welded weld joint of the container barrel body.According to the method, the number of rework times and the probability can be reduced.

Description

technical field [0001] The invention relates to a welding method of a martensitic heat-resistant steel for closing welds of a steam cooler of a secondary reheating unit, and belongs to the field of high-parameter container manufacturing. Background technique [0002] With the increase of unit parameters, the double reheat ultra-supercritical 1000MW unit technology has been popularized and applied in China, and the design and manufacture of the steam cooler in the double reheat unit is based on the advantage of superheat technology to improve the thermal efficiency of steam , so that the operating parameters of this type of design have been greatly improved, and the material requirements for the metal materials of such containers have been improved, especially for the shell manufacturing of evaporator coolers. 9-12%Cr martensitic heat-resistant steel (such as SA336F91) is used. This type of steel has been widely used in the main steam pipeline. The welding technology of 9-12%...

AI Technical Summary

Problems solved by technology

For martensitic heat-resistant steel (such as SA336F91), problems such as weld cracks and abnormal hardness are prone to occur during the manufacturing process. For example, in the Chinese patent application number 201410273641.4, some delayed crack defects can even be detected after delivery. This undoubtedly brought unprecedented risks to the manufacturing plant, and at the same time increased the labor and material costs of the manufacturing plant. At the same time, the repeated repairs of the welds also brought safety risks to the subsequent operation of the equipment.

Images