A wear-resistant powder-cored welding wire with extremely low thermal crack sensitivity

Abstract

The invention relates to a surfacing powder cored welding wire which is wear-resistant and has extremely low thermal crack sensitivity, and is used for the surfacing powder cored welding wire which is wear-resistant and has extremely low thermal crack sensitivity at the severely worn parts of a circulating fluidized bed boiler; the powder core components of the surfacing powder cored welding wire and their mass percentage ranges are as follows: C 0.2-0.5%, Cr 8-16%, Mo 1-3%, Ni 0.5-2%, Ti 0.2-1%, Nb 0.2-1%, Mn 1-2%, B 0.5-1.5%, Si 1-2.5%, RE 0.1-0.5%, TiB2 5-15%, Nb2N 3-5%, NaF 0-2%, CaF2 0-3.5%, K2CO3 0-2.5%, and Fe balance.

Description

Technical Field

[0001] The present invention relates to a cladding powder cored welding wire which is wear-resistant and has extremely low thermal crack sensitivity, and is used for the cladding powder cored welding wire which is wear-resistant and has extremely low thermal crack sensitivity at the severely worn parts of a circulating fluidized bed boiler, and is applied to the wear protection of the pipe walls, bends, through-wall pipes, welds and other irregular pipe walls in the four corners of the furnace of the circulating fluidized bed boiler, and the area around the furnace flue outlet. Background Art

[0002] Circulating fluidized bed boilers have the advantages of wide fuel adaptability (high-quality coal, high-sulfur coal, high-ash coal, high-ash high-sulfur coal, coal gangue, peat, etc.), high combustion efficiency (97.5%~99.5%), high-efficiency desulfurization (>90%), low emission of nitrogen oxides and other pollutants, wide load adjustment range, small furnace cross-sectional area, etc., and are one of the economical and effective low-pollution combustion technologies. Due to the flow characteristics of materials in circulating fluidized bed boilers, the materials in the furnace are strongly mixed, which makes the furnace heat load more uniform than that of pulverized coal furnaces, and also causes a large amount of materials to flush the heating surface, causing serious wear of the metal parts of the circulating fluidized bed boiler, especially some special parts, where the degree of wear is abnormally prominent, such as the transition zone between the lower furnace guard belt and the water-cooled wall, the pipe wall, bend pipe, through-wall pipe, weld and other irregular pipe walls in the four corners of the furnace, and around the furnace flue outlet, etc., the most serious can reach 5mm / 1000h. In order to solve the serious wear problem of circulating fluidized bed boilers, various surface technology methods are usually used to prevent the wear of boiler metal parts, such as nitriding or chromizing of furnace tubes, electroplating and hot dip plating, protective tiles, thermal spraying, spray welding, surfacing, etc. In recent years, surfacing technology has been widely used to protect the severely worn parts of circulating fluidized bed boilers. This technology is a very effective anti-wear method. However, anti-wear materials are the most critical and core issue in ensuring the quality of surfacing technology. The quality of welding materials determines the anti-wear effect of the boiler. In recent years, various anti-wear welding materials for circulating fluidized bed boilers have been developed at home and abroad. According to industry market information and practical experience, there are some general deficiencies, such as poor professional applicability of materials, poor welding processability, unsmooth welding, sticky conductive nozzles, large spatter, poor weld bead formability, easy to generate pores, cracks in the weld layer, low hardness of the weld layer, poor high-temperature wear performance or high material cost, etc. The above problems all affect the application of welding materials to a certain extent. Therefore, for some special parts of circulating fluidized bed boilers with severe wear, Summary of the invention

[0003] The purpose of the present invention is to effectively solve the problems of rapid wear and thinning and pipe penetration and bursting in some severely worn parts of a circulating fluidized bed boiler. The present invention provides a wear-resistant and extremely low thermal crack sensitivity surfacing powder cored welding wire for severely worn parts of a circulating fluidized bed boiler.

[0004] This welding wire material is very suitable for circulating fluidized bed boiler working conditions. It has good welding processability, extremely small spatter, beautiful weld formability, no pores in the weld layer, no cracks inside and outside the weld layer, high weld hardness, very low friction coefficient, excellent wear resistance and relatively reasonable material cost. The product technology reaches or exceeds the advanced foreign level, and realizes efficient protection of severe wear of the heating surface of my country's circulating fluidized bed boilers.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The wear-resistant and extremely low thermal crack sensitivity surfacing powder core welding wire for severely worn parts of circulating fluidized bed boilers provided by the present invention adopts a powder core wrapped in a low-carbon steel sheath and is formed by rolling, drawing and reducing the diameter one by one.

[0007] A cladding powder cored welding wire that is wear resistant and has extremely low thermal crack sensitivity, wherein the powder core components and mass percentage ranges of the cladding powder cored welding wire are as follows:

[0008] C 0.2~0.5%, Cr 8~16%, Mo 1~3%, Ni 0.5~2%, Ti 0.2~1%, Nb 0.2~1%, Mn 1~2%, B 0.5~1.5%, Si 1~2.5%, RE 0.1~0.5%, TiB2 5~15%, Nb2N 3~5%, NaF 0~2%, CaF2 0~3.5%, K2CO3 0~2.5%, Fe balance.

[0009] Furthermore, the powder core filling rate of the powder cored welding wire is 26% to 30%.

[0010] Furthermore, the particle size of the powder core of the powder core welding wire is 70 to 300 meshes.

[0011] The method for preparing a powder cored welding wire of the present invention comprises the following steps:

[0012] A carbon steel strip with a width of 10 mm and a thickness of 0.35 mm is used as an outer sheath, and the steel strip is rolled into a U-shape, and then powder is added into the U-shaped groove according to the proportion of powder core powder in the welding wire of the present invention. Then the U-shaped groove is closed to wrap the powder therein, and the powder core welding wire with a diameter of Φ1.6 mm is made through the processes of rolling by a forming machine, drawing by a wire drawing unit, and reducing the diameter.

[0013] The wear-resistant and extremely low thermal crack sensitivity surfacing powder cored welding wire for severely worn parts of circulating fluidized bed boilers provided by the present invention is suitable for various types of welding equipment such as MIG, MAG or CO2 gas shielded welding, and can be welded manually or automatically. No preheating is required during welding, and surfacing can be directly performed on the surface of the workpiece. The surfacing layer does not produce cracks, the welding process is good, the wire is smooth, the conductive nozzle does not stick, and almost no spatter is generated. The weld bead has beautiful formability, the weld layer has high hardness, and the friction coefficient is very low. Especially under high temperature conditions above 500-600°C, it has high hardness, and the friction coefficient is only about 1 / 3 of the existing standard welding wire, and has excellent high temperature wear resistance.

[0014] Due to the scientific and reasonable control of alloying elements, on the one hand, the weld structure can be self-quenched to form a martensitic structure in the air-cooling environment during welding, and the grains are fine and the structure is evenly refined, ensuring the high hardness, strength and toughness of the weld layer; on the other hand, the brittle delta ferrite rich in Cr, Mo, W, etc. is almost not precipitated in the weld, ensuring the low thermal crack sensitivity of the weld structure and avoiding the occurrence of cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The appearance of the welding layer formed by surfacing welding on the tube bank of a circulating fluidized bed boiler with the powder core welding wire of the present invention;

[0016] Figure 2 It is the metallographic structure of the cross section of the weld layer;

[0017] Figure 3 It is the friction coefficient curve of the welding layer at 600℃. Implementation

[0018] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0019] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0020] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0021] A cladding powder cored welding wire that is wear resistant and has extremely low thermal crack sensitivity, wherein the powder core components and mass percentage ranges of the cladding powder cored welding wire are as follows:

[0022] C 0.2~0.5%, Cr 8~16%, Mo 1~3%, Ni 0.5~2%, Ti 0.2~1%, Nb 0.2~1%, Mn 1~2%, B 0.5~1.5%, Si 1~2.5%, RE 0.1~0.5%, TiB2 5~15%, Nb2N 3~5%, NaF 0~2%, CaF2 0~3.5%, K2CO3 0~2.5%, Fe balance.

[0023] Furthermore, the powder core filling rate of the powder cored welding wire is 26% to 30%.

[0024] Furthermore, the particle size of the powder core of the powder core welding wire is 70 to 300 meshes.

[0025] The method for preparing a powder cored welding wire of the present invention comprises the following steps:

[0026] A carbon steel strip with a width of 10 mm and a thickness of 0.35 mm is used as an outer sheath, and the steel strip is rolled into a U-shape, and then powder is added into the U-shaped groove according to the proportion of powder core powder in the welding wire of the present invention. Then the U-shaped groove is closed to wrap the powder therein, and the powder core welding wire with a diameter of Φ1.6 mm is made through the processes of rolling by a forming machine, drawing by a wire drawing unit, and reducing the diameter.

[0027] The wear-resistant and extremely low thermal crack sensitivity surfacing powder cored welding wire for severely worn parts of circulating fluidized bed boilers provided by the present invention is suitable for various types of welding equipment such as MIG, MAG or CO2 gas shielded welding, and can be welded manually or automatically. No preheating is required during welding, and surfacing can be directly performed on the surface of the workpiece. The surfacing layer does not produce cracks, the welding process is good, the wire is smooth, the conductive nozzle does not stick, and almost no spatter is generated. The weld bead has beautiful formability, the weld layer has high hardness, and the friction coefficient is very low. Especially under high temperature conditions above 500-600°C, it has high hardness, and the friction coefficient is only about 1 / 3 of the existing standard welding wire, and has excellent high temperature wear resistance.

[0028] Due to the scientific and reasonable control of alloying elements, on the one hand, the weld structure can be self-quenched to form a martensitic structure in the air-cooling environment during welding, and the grains are fine and the structure is evenly refined, ensuring the high hardness, strength and toughness of the weld layer; on the other hand, the brittle delta ferrite rich in Cr, Mo, W, etc. is almost not precipitated in the weld, ensuring the low thermal crack sensitivity of the weld structure and avoiding the occurrence of cracks. Example

[0029] Take C 0.3%, Cr 8%, Mo 2%, Ni 0.8%, Ti 0.4%, Nb 0.6%, Mn 2%, B 0.8%, Si2%, RE 0.2%, TiB2 10%, Nb2N 3%, NaF 1%, CaF2 1.5%, K2CO3 2%, Fe balance. Put all the powders into the powder mixer and stir them thoroughly to mix them evenly. Then use a carbon steel strip with a width of 10mm and a thickness of 0.35mm as the outer skin, roll the steel strip into a U shape, then put the evenly mixed powder into the carbon steel strip, the powder core filling rate is 28%, then close the U-shaped groove of the carbon steel strip to wrap the powder, and then go through the forming machine rolling, wire drawing unit step by step drawing, diameter reduction and other processing procedures to make a powder core welding wire with a diameter of Φ1.6mm. Example

[0030] Take C 0.4%, Cr 12%, Mo 2%, Ni 2%, Ti 0.8%, Nb 0.6%, Mn 1%, B 0.8%, Si1%, RE 0.1%, TiB2 9%, Nb2N 3%, NaF 1%, CaF2 2%, K2CO3 1.5%, Fe balance. Put all the powders into the powder mixer and stir them well to mix them evenly. Then use a carbon steel strip with a width of 10mm and a thickness of 0.35mm as the outer skin, roll the steel strip into a U shape, then put the evenly mixed powder into the carbon steel strip, the powder core filling rate is 28%, then close the U-shaped groove of the carbon steel strip to wrap the powder, and then go through the forming machine rolling, wire drawing unit step by step drawing, diameter reduction and other processing procedures to make a powder core welding wire with a diameter of Φ1.6mm. Example

[0031] Take C 0.35%, Cr 9%, Mo 1%, Ni 1.5%, Ti 0.6%, Nb 0.3%, Mn 1.5%, B 0.5%, Si 2%, RE 0.2%, TiB2 6%, Nb2N 5%, NaF 2%, CaF2 3%, K2CO3 1%, Fe balance. Put all the powders into the powder mixer and stir them well to mix them evenly. Then use a carbon steel strip with a width of 10mm and a thickness of 0.35mm as the outer skin, roll the steel strip into a U shape, then put the evenly mixed powder into the carbon steel strip, the powder core filling rate is 30%, then close the U-shaped groove of the carbon steel strip to wrap the powder, and then make it into a powder core welding wire with a diameter of Φ1.6mm through the forming machine rolling, wire drawing unit drawing, diameter reduction and other processing procedures.

[0032] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0033] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A cladding powder cored welding wire with wear resistance and extremely low thermal crack sensitivity, characterized in that: The powder core components and mass percentage ranges of the cladding powder cored welding wire are as follows: C 0.2~0.5%, Cr 8~16%, Mo 1~3%, Ni 0.5~2%, Ti 0.2~1%, Nb 0.2~1%, Mn 1~2%, B 0.5~1.5%, Si 1~2.5%, RE 0.1~0.5%, TiB2 5~15%, Nb2N 3~5%, NaF 0~2%, CaF2 0~3.5%, K2CO3 0~2.5%, Fe balance.

2. The wear-resistant and extremely low thermal crack sensitivity surfacing powder cored welding wire according to claim 1, characterized in that: The powder core filling rate of the powder core welding wire is 26% to 30%.

3. The wear-resistant and extremely low thermal crack sensitivity surfacing powder cored welding wire according to claim 1, characterized in that: The powder core particle size of the powder core welding wire is 70-300 meshes.

Images