CN115026379A

CN115026379A - Welding process of water tank type water-cooled furnace mouth of steel-making converter

Info

Publication number: CN115026379A
Application number: CN202210775823.6A
Authority: CN
Inventors: 史亚军
Original assignee: Xinjiang Bagang Jiayu Industrial Material Co ltd
Current assignee: Xinjiang Bagang Jiayu Industrial Material Co ltd
Priority date: 2022-07-03
Filing date: 2022-07-03
Publication date: 2022-09-09

Abstract

The invention discloses a welding process of a water tank type water-cooled furnace mouth of a steel converter, wherein the drying temperature of a low-hydrogen welding rod is as follows: and (2) keeping the temperature at 350-380 ℃ for: 1.5-2 h, drying, slowly cooling, and placing in a heat preservation box at 110-120 ℃ for storage for later use; when the missing edge of the welding groove is 1-3 mm, polishing and flattening; when the edge is missing more than 3mm, using a low-hydrogen type welding rod with the diameter not more than 3.2mm, and grinding and flattening; when the wind speed of the welding operation area exceeds 8m/s in manual electric arc welding and exceeds 2m/s in gas shielded electric arc welding and flux-cored wire electric arc welding, a wind shelter is arranged; when the environment temperature of the welding operation area is lower than 0 ℃, the base metal in the range of more than or equal to two times of the thickness of the steel plate and not less than 100mm in each direction of the welding area of the component is heated to more than 20 ℃ and then can be welded; the T-shaped joint, the cross-shaped joint, the angle joint and the butt joint adopt double-groove symmetrical welding to replace single-groove asymmetrical welding; low-hydrogen and ultra-low-oxygen welding rods or gas shielded arc welding are adopted, and stress is eliminated after welding.

Description

Welding process of water tank type water-cooled furnace mouth of steel-making converter

Technical Field

The invention relates to a welding process of a water tank type water-cooling furnace mouth of a steel-making converter.

Background

The steel-making converter is the main equipment for steel-making, and the water-cooled converter mouth is a key part on the converter. In actual production, the water-cooled furnace mouth is positioned at the upper part of the converter for smelting molten steel, and the temperature is above 1600 ℃; in order to protect the furnace mouth, a water-cooled furnace mouth which is forcibly cooled by circulating water is generally adopted. Circulating water is introduced into the interior of the water tank, and the inlet pressure is (3-4) multiplied by 10' N/m; water leakage is easy to occur at the water-cooled furnace mouth in the production process, and the furnace shutdown is forced to cause a production shutdown accident.

The water-cooled furnace mouth has the advantages that: the method can reduce the adhesive on the furnace mouth, is easy to remove even if the adhesive is adhered, can strengthen the rigidity of the furnace mouth, reduce the deformation of the furnace mouth, improve the stress state and prolong the service life of the metal shell of the furnace cap and the furnace lining. The main disadvantages of the water-cooled furnace mouth are: once a large amount of water leaks due to damage, explosion is easily caused by improper operation during furnace shaking; in addition, the water-cooling furnace mouth is easy to damage and leak water, so that the maintenance workload of the equipment is increased, but the danger can be avoided only by paying attention to the inspection. The advantages are far more than the disadvantages, so the water-cooling furnace mouth is widely applied. The water-cooling furnace mouth structure form: the water-cooled furnace mouth has two structural forms, namely a water tank type and a cast iron buried pipe type. The structure of the water tank type water cooling furnace mouth is a steel plate welding structure, the cooling intensity is high, the working effect is good, the manufacture is easy, the repair welding can be carried out when water leaks, and the maintenance is convenient.

Firstly, paying attention to the fact that a water outlet of backwater is close to the top of a water tank so as to reduce water vapor accumulated on the top of the water tank; secondly, the inner side surface of the furnace mouth is designed into an inverted cone, and the inclination angle is about 15 degrees, so that the coal gas can flow and tap, and the slag can not be bonded during slag tapping; and thirdly, the bottom plate extends out of the inverted cone-shaped inner side plate by about 15mm to prevent the furnace gas from scouring and ablating the welding seam to cause water leakage.

Circulating water enters from a water inlet pipe of the water-cooling furnace mouth, flows from a head opening of the phi 152 x 20 annular pipe to a tail opening, and is filled into the furnace mouth cavity, two water-stop plates are arranged in the cavity, the interior of the furnace mouth is divided into a plurality of cavities, after one cavity is forcedly filled, the circulating water is circulated to the next cavity and then flows into a water outlet, and the water cooling circulation of the whole body is achieved.

The stress distribution of the welding seam at the two water stop plates is complex, and the welding seam cracks and leaks water under the condition of rapid cooling and rapid heating. The upper cover plate consists of 3 fan-shaped plates, and if high-pressure steam is formed, the welding seam of the joint is easy to crack; the water inlet is blocked and water is not removed, and cracks can be generated on the base metal near the welding seam. Especially, because the two plugs of the annular pipe are dead corners of welding seams, slag inclusion and air holes are easy to occur during welding, and the water leakage phenomenon is caused. The reasons for the damage of the water-cooled furnace mouth are as follows: when the furnace mouth is used, the impact load caused by flushing is generated continuously by the cooling water flow from the inside. After the impact, the strength of the steel plate is reduced and aged, impact fatigue is generated at the increased part, fatigue cracks are continuously expanded, the effective area of the steel plate bearing load is continuously increased, and the steel plate is cracked. In the operation process, the hopper added with the scrap steel is in contact friction with the annular pipe of the furnace mouth, so that the impact load formed by the external impact of the scrap steel hopper and the like on the surface of the furnace mouth is inevitably generated, and the fatigue is accelerated due to the high impact energy, and the cracking of the steel plate is further caused. When the furnace mouth works in a state of temperature repeated change for a long time, thermal stress cycle change can be generated to cause thermal fatigue, and the furnace mouth can generate plastic cracking. The panel of the furnace mouth is easy to deform and crack due to improper operation or error of production personnel, improper distribution of the water-proof plate when manufacturing individual furnace mouths, blockage of foreign matters at backwater parts and the like. The water tank annular pipe is manufactured by adopting a 360-degree integral annular pipe, and a medium-low pressure boiler pipe (20 g) with high comprehensive mechanical properties such as strength, plasticity, toughness and the like is selected to manufacture the annular pipe of the water cooling furnace mouth. Regular monitoring advances, leaving water temperature, guarantees abundant water supply flow, when water supply pressure and flow are less than the specified value, inspects the unblocked condition of business turn over water pipe immediately, installs the filter additional to fire door water tank main water supply pipe simultaneously, guarantees the unblocked of water route, prevents to cause the annular pipe fracture because of rivers are not enough or the pipe network blocks.

Disclosure of Invention

The invention aims to provide a welding process of a water tank type water-cooling furnace mouth of a steel-making converter, which can quickly and effectively weld a cracking part of the water-cooling furnace mouth and reduce production loss.

The invention adopts the technical scheme that a welding process of a water tank type water-cooling furnace mouth of a steel-making converter,

1) and the welding operation requirement is as follows: before the welding rod, the melting nozzle, the welding flux and the flux-cored wire are used, the welding rod, the melting nozzle, the welding flux and the flux-cored wire are dried according to the specification of a product; drying temperature of the low-hydrogen type welding rod: and (2) keeping the temperature at 350-380 ℃ for: 1.5-2 h, drying, slowly cooling, and placing in a heat preservation box at 110-120 ℃ for storage for later use; when in use, the utility model is placed in a heat preservation cylinder; the dried low-hydrogen type welding rod is placed in the atmosphere for more than 4 hours and is dried again; the repeated drying times of the welding rod are not more than 2; the wet welding rod cannot be used; the solid welding wire and the nozzle guide pipe must be free of oil stain and rust, and the copper plating layer is intact;

2) the surface of the weld groove meets the following requirements: the welding groove is processed by flame cutting or a mechanical method, and when the edge is 1-3 mm, the welding groove is polished and leveled; when the edge is missing more than 3mm, using a low-hydrogen type welding rod with the diameter not more than 3.2mm, and grinding and flattening;

3) the welding operation environment meets the following requirements: setting a wind shelter or adopting other wind prevention measures when the wind speed of a welding operation area exceeds 8m/s in manual electric arc welding and exceeds 2m/s in gas shielded electric arc welding and flux-cored wire electric arc welding; when the environmental temperature of a welding operation area is lower than 0 ℃, the base metal with the thickness more than or equal to two times of the thickness of the steel plate and not less than 100mm in each direction of a component welding area can be welded after being heated to more than 20 ℃, and the temperature is not lower than the temperature in the welding process;

4) the arc striking plate, the leading-out plate and the base plate meet the following requirements: an arc striking plate and an extraction plate are required to be arranged at two ends of a main welding line of the T-shaped joint, the cross-shaped joint, the angle joint and the butt joint, the materials of the arc striking plate and the extraction plate are the same as those of a welded parent metal, the form of a groove is the same as that of the welded welding line, the extraction length of the welding line of the shielded metal arc welding and the gas shielded arc welding is more than 25mm, the widths of the arc striking plate and the extraction plate are more than 50mm, the length is preferably 1.5 times of the plate thickness and not less than 30mm, and the thickness is not less than 6 mm; the steel liner is welded in the joint groove in a positioning welding mode, the thickness of the positioning welding seam does not exceed 2/3 of the designed thickness of the welding seam, the length of the positioning welding seam is larger than 40mm, the distance between every two adjacent positioning welding seams is 500-600 mm, the arc craters are filled, and the preheating temperature of the positioning welding is higher than the preheating temperature of formal welding;

5) and the process measures for preventing the layer tearing are as follows: when the T-shaped joint, the cross joint and the angle joint are welded, the asymmetric welding of a single-sided groove is replaced by the symmetric welding of a double-sided groove; overlaying a plastic transition layer on the surface of the base metal plate in the groove by using a low-strength welding rod; when the plate thickness of the box column corner joint of the II type steel and the above II type steel is more than or equal to 80mm, removing a hardening layer on the flame cutting surface of the plate edge by a mechanical method; the width of the heating plate on each side surface of the welding line of the component is at least 3 times of the thickness of the steel plate and is not less than 200 mm.

And (4) checking standard requirements, wherein the held drawing is completely consistent with the drawing issued by the production plan and the requirements according to the production plan and the production progress, and the quality and process technicians finish the detection or judgment of the quality condition of the component together. Filling the quality conditions in the processes of blanking, assembling, welding and heat treatment in the production process; summarizing and compiling a report of the quality condition of the component product; the flatness requirements of the butt joint are as follows: the flatness f of the butt joint should not exceed 3% of the plate thickness over a 200mm length but not more than 1 mm. The misalignment requirement of the butt joint is as follows: the plane misalignment h of the two plates of the butt joint should not exceed 3 percent of the plate thickness but not be more than 1 mm. The quality of the welding seam is as follows: should be free of cracks, unfused, lack of weld-through, free of air holes, flash, etc. Performance: the trial assembly and the service performance meet the product requirements. All defects (problems) in component inspection should be reflected in the form of data, such as: geometric dimension, surface finish, weld quality and the like. After long-term tracking observation and exploration, the Xinjiang Bagang Jia regional industrial materials company improves the technical measures, the service life of the Xinjiang Bagang Jia regional industrial materials company is integrally prolonged, the service life of a water-cooled furnace mouth is longer, and more than 8000 heats of steel making can be realized.

Detailed Description

A welding process of a water tank type water-cooling furnace mouth of a steel-making converter,

1) and the welding operation requirement is as follows: before the welding rod, the melting nozzle, the welding flux and the flux-cored wire are used, the welding rod, the melting nozzle, the welding flux and the flux-cored wire are dried according to the specification of a product; drying temperature of the low-hydrogen type welding rod: and (2) keeping the temperature at 350-380 ℃ for: 1.5-2 h, drying, slowly cooling, and placing in a heat preservation box at 110-120 ℃ for storage for later use; when in use, the utility model is placed in a heat preservation cylinder; the dried low-hydrogen type welding rod is placed in the atmosphere for more than 4 hours to be dried again; the repeated drying times of the welding rod are not more than 2 times; the wet welding rod cannot be used; the solid welding wire and the nozzle guide pipe must be free of oil stain and rust, and the copper plating layer is intact;

2) the surface of the weld groove meets the following requirements: the welding groove is processed by flame cutting or a mechanical method, when flame cutting is adopted, the quality of a cutting surface meets the corresponding regulations of national standard ZBJ-59002.3 hot cutting, gas cutting quality and size deviation, and when the edge is 1-3 mm, the cutting surface is polished and leveled; when the edge is missing more than 3mm, using a low-hydrogen type welding rod with the diameter not more than 3.2mm, and grinding and flattening; before welding, a welder checks the quality of assembly and surface cleaning of a welding part, the assembly clearance of a welding groove of various welding methods does not exceed 3mm except for a penetration requirement, when the assembly clearance of the groove exceeds an allowable deviation specification, the welding can be carried out on one side or two sides of the groove and ground to meet the requirement, but when the assembly clearance of the groove exceeds the thickness of a thinner plate by 2 times or is more than 20mm, the length of a component is not increased and the assembly clearance is reduced by applying a surfacing method; when the assembly clearance of the lap joint and the T-shaped angle joint exceeds 1mm or the assembly clearance of the T, K, Y-shaped joint of the pipe exceeds l.5mm, the size of the welded leg is at least the designed leg size plus the clearance, but when the assembly clearance of the T-shaped angle joint exceeds 5mm, the plate end is subjected to surfacing and grinding in advance or the welding is carried out after surfacing and filling in the clearance.

The welding process file should meet the following requirements:

before construction, welding technical responsible personnel compile welding process files according to qualified welding process evaluation results, and carry out technical background to related operators, and the regulations of the process files are strictly followed in construction;

the welding process file should include the following: a welding method or a combination of welding methods; the grade, thickness and other relevant dimensions of the base material; welding material type and specification; allowable deviation of the welding joint form, the groove shape and the size; the requirements of clamps, tack welds and gaskets; welding current, welding voltage, welding speed, back chipping requirements, welding sequence and other welding process parameters. The welding operation environment should meet the following requirements: when the wind speed in the welding operation area exceeds 8m/s in manual arc welding and exceeds 2m/s in gas shielded arc welding and flux-cored arc welding, a wind shelter is arranged or other wind prevention measures are taken. When cross-over wind or a blower exists in a welding operation area in a manufacturing workshop, a wind shielding device is also arranged according to the specification; the relative humidity of the welding operation area is not more than 90%; when the surface of the weldment is wet or covered by ice and snow, heating, dehumidifying and dehumidifying measures are adopted; when the environmental temperature of the welding operation area is lower than 0 ℃, the base material in the range of not less than l00mm, which is larger than or equal to two times the thickness of the steel plate in each direction of the welding area of the component, can be welded after being heated to more than 20 ℃, and the temperature is not lower than the temperature in the welding process. The actual heating temperature is determined according to the structural characteristics of the component, the type and quality grade of steel, the weldability, the content of diffusible hydrogen in deposited metal of welding materials, the welding method, the welding heat input and other factors, the heating temperature is higher than the welding preheating temperature at normal temperature, and the operation scheme can be implemented after being approved by welding technical responsibility personnel. The operation scheme should ensure that the operation skill of a welder is not influenced by low temperature of the environment, and meanwhile, necessary heat preservation measures are taken for the components.

The arc striking plate, the lead-out plate and the base plate meet the following requirements: strictly forbidding striking fire, striking arc or installing a welding clamp on the base metal except for bearing dynamic load and needing fatigue checking and calculating the welding seam of the component; the base material except the welding seam is not required to be ignited and arc-struck; an arc striking plate and an extraction plate must be arranged at two ends of a main welding seam of the T-shaped joint, the cross-shaped joint, the angle joint and the butt joint, the material of the arc striking plate and the extraction plate is the same as that of a welded parent metal, the form of a groove is the same as that of the welded seam, and materials made of other materials are forbidden to be used as the arc striking plate and the extraction plate; the leading-out length of the welding seam of the shielded metal arc welding and the gas shielded arc welding is more than 25 mm. The widths of the arc striking plate and the lead-out plate are more than 50mm, the lengths are preferably 1.5 times of the plate thickness and not less than 30mm, and the thickness is not less than 6 mm; and after welding, removing the arc striking plate and the lead-out plate by flame cutting, and polishing and flattening. The striking plate and the drawing plate can not be dropped by hammering. The welding material used should be the same as the formal welding. Tack welds should have the same quality requirements as the final weld. The steel liner is welded in the joint groove in a positioning mode, the thickness of a welding line of the positioning welding is not larger than 2/3 of the thickness of a designed welding line, the length of the welding line of the positioning welding is preferably larger than 40mm, the distance is preferably 500-600 mm (according to specific conditions), and the arc craters are filled with the positioning welding. The preheating temperature of the positioning welding is higher than the preheating temperature of the formal welding. When the tack weld has air holes or cracks, the tack weld must be removed and then re-welded.

The process measures for preventing the layer tearing are as follows: when the T-shaped joint, the cross joint and the angle joint are welded, the following welding process measures for preventing the sheet layer from tearing are preferably adopted. The asymmetric welding of a single-sided groove is replaced by the symmetric welding of a double-sided groove; surfacing a plastic transition layer on the surface of the base metal plate in the notch by adopting a low-strength welding rod; when the plate thickness of the box column corner joint of II or above II steel is more than or equal to 80mm, the plate edge flame cutting surface is preferably removed with a mechanical method. Low hydrogen, ultra low oxygen type electrodes or gas shielded arc welding are used. And (4) stress relief treatment after welding, when the stress relief after welding is required, according to the size of the component, the stress relief of the component is preferably relieved by adopting heating furnace integral annealing or electric heater local annealing in factory manufacture, and the stress relief can be realized by adopting a vibration method only when the structure size is stabilized. The postweld heat treatment is in accordance with the regulations of the national standard (GB/T6046) for the postweld heat treatment method of welded components of carbon steel and low alloy steel. When an electric heater is used for carrying out local stress relief heat treatment on a welding component, the following requirements are met: the heating, temperature measurement and temperature control performances of the heating equipment with the automatic temperature controller meet the use requirements; the width of the heating plate (belt) on each side surface of the component welding seam is at least 3 times of the thickness of the steel plate and is not less than 200 mm; both sides of the heating plate (belt) outer member are preferably covered with heat insulating material.

Claims

1. A welding process of a water tank type water-cooling furnace mouth of a steelmaking converter is characterized by comprising the following steps:

1) and the welding operation requirement is as follows: before the welding rod, the melting nozzle, the welding flux and the flux-cored wire are used, the welding rod, the melting nozzle, the welding flux and the flux-cored wire are dried according to the specification of a product; drying temperature of the low-hydrogen type welding rod: 350-380 ℃, heat preservation time: 1.5-2 h, drying, slowly cooling, and placing in a heat preservation box at 110-120 ℃ for storage for later use; when in use, the utility model is placed in a heat preservation cylinder; the dried low-hydrogen type welding rod is placed in the atmosphere for more than 4 hours to be dried again; the repeated drying times of the welding rod are not more than 2; the wet welding rod cannot be used; the solid welding wire and the nozzle guide pipe must be free of oil stain and rust, and the copper plating layer is intact;

3) the welding operation environment meets the following requirements: when the wind speed in the welding operation area exceeds 8m/s in manual electric arc welding and exceeds 2m/s in gas shielded electric arc welding and flux-cored wire electric arc welding, a wind-proof shed is arranged as a wind-proof measure; when the environment temperature of a welding operation area is lower than 0 ℃, the base metal in the range that the thickness of the steel plate is more than or equal to two times and is not less than 100mm in each direction of the welding area of the component is heated to be more than 20 ℃ and then can be welded, and the temperature is not lower than the temperature in the welding process;

4) the arc striking plate, the lead-out plate and the backing plate meet the following requirements: the two ends of the main welding seam of the T-shaped joint, the cross-shaped joint, the angle joint and the butt joint are necessarily provided with an arc striking plate and an extraction plate, the materials of the arc striking plate and the extraction plate are the same as those of a welded parent metal, the form of a groove is the same as that of the welded seam, the extraction length of the welding seam of the shielded metal arc welding and the gas shielded arc welding is more than 25mm, the widths of the arc striking plate and the extraction plate are more than 50mm, the length of the arc striking plate and the extraction plate is preferably 1.5 times of the thickness of the plate and is not less than 30mm, and the thickness of the arc striking plate and the extraction plate is not less than 6 mm; the steel liner is welded in the joint notch in a positioning mode, the thickness of a positioning welding seam does not exceed 2/3 of the thickness of a designed welding seam, the length of the positioning welding seam is larger than 40mm, the interval is 500-600 mm, arc pits are filled, and the preheating temperature of the positioning welding is higher than the preheating temperature of formal welding;

5) and the process measures for preventing the layer tearing are as follows: when the T-shaped joint, the cross joint and the angle joint are welded, the asymmetric welding of a single-sided groove is replaced by the symmetric welding of a double-sided groove; surfacing a plastic transition layer on the surface of the base metal plate in the notch by adopting a low-strength welding rod; when the plate thickness of the box column corner joint of the II type steel and the above II type steel is more than or equal to 80mm, removing a hardening layer on the flame cutting surface of the plate edge by a mechanical method; the width of the heating plate on each side surface of the welding line of the component is at least 3 times of the thickness of the steel plate and is not less than 200 mm.