JPS6017638B2 - Welding method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of welding while measuring temperature.

As shown in FIG. 1, during welding, a heat-affected zone 3 is formed in the welded material 1 in the vicinity of the weld metal portion 2 due to heat application during welding.

The material to be welded undergoes a thermal history of rapid heating and cooling during welding, so depending on the material, carbides may precipitate in the heat affected zone, harden, and become sensitized, resulting in cracking or cracking in the usage environment. There is a risk of accidents such as destruction and corrosion, so be sure to fully understand the condition of the heat-affected zone when welding.
Appropriate measures must be taken depending on the situation.

Austenitic stainless steel is heated to 500 to 800 qo, causing Cr carbide to precipitate at grain boundaries and cause intergranular corrosion. Therefore, welding especially at this temperature of 200 to 800℃
It is necessary to simulate how the temperature castle is heated to. Conventionally, the temperature of the welding zone has been controlled using a contact type surface thermometer, or by attaching thermocouples 4 to each point of the welded material 1 as shown in Fig. 2 to measure the temperature of the welded material and perform preheating and The temperature between passes was controlled.

However, these methods can only control the temperature in the vicinity of the weld to prevent it from rising above a certain temperature or falling below a certain temperature, and it is not possible to continuously measure the position and temperature. Therefore, it has not been possible to understand the distribution of temperature ranges that should be noted, and to use heat input control that changes the width of the temperature range depending on the usage environment and the distribution of the temperature range for inspection and maintenance management of welded parts. An object of the present invention is to provide a welding method that allows maintenance and management of welded parts.

The present invention is a method for welding while measuring the temperature of the welding heat-affected area on the surface of the workpiece, in which a temperature measuring device is scanned in a direction perpendicular to the welding direction, and a predetermined temperature range perpendicular to the welding direction is measured in the welding direction. The welding method is characterized by continuous measurement in the form of a strip.

According to the present invention, it is possible to observe the width and fluctuation state of the temperature castle, so it is possible to maintain and manage the welded part.

The method of the present invention will be explained below with reference to the drawings.

FIG. 3 is a diagram showing the configuration of a baggage device that implements the present invention. A groove 5 is provided in the material to be welded 1 of the pipe, and the non-consumable electrode 7 protruded from the welding torch 6 is inserted into the joint 6 to form a groove 5 between the material to be welded 1 and the non-consumable fin 7. Welding is performed by generating an arc and rotating around the workpiece 1 to form weld metal 2 while feeding a filler wire 8 into the arc depending on the situation. Welding conditions such as welding current, voltage, welding speed, and filler wire feeding speed are controlled by a welding control device 9. The temperature is measured using a temperature measuring bag 11 at a temperature measuring position 10 slightly away from the arc point, and is recorded on a recorder 12. The recorder 12 uses the information obtained from the temperature measurement device 11 to continuously measure the temperature of the castle within a certain temperature range in the temperature measurement device 10, and records a band-shaped temperature region 15 on the recording paper 13. . Further, the measured width of the temperature range 15 is input to the heat input controller 14, which has previously set the temperature range of the optimum heat input amount. The heat input controller 14 performs heat input control by comparing the set value and the output from the recorder 12 and controlling the welding control device. Further, although not shown, a detector measures the center position of the test point and the temperature measurement position pupil 10, and records the test point center line 16 and the measurement position signal line 17 on the recording paper 13. SUS304 stainless steel pipes were welded using the above-described welding machine while controlling heat input. Set the temperature measurement position at a point two yards behind the welding line from the arc point, and measure the temperature at 500 to 800°C in the welding direction while scanning the temperature measuring device in a direction perpendicular to the welding line.
The temperature range was recorded continuously in a band. FIG. 4 shows the temperature measurement equipment used for temperature measurement. Infrared rays emitted from the object 18 pass through a scanning mirror 19 and a fixed mirror 20 to a lens 21 and are focused and guided to a detector 22. The collected infrared light is converted into an electrical signal by the detector 22, amplified by the amplifier 23, and output. Temperature calibration is performed using a black body 24. The temperature measurement scan on the object 18 is performed by the rotation of the mirror 19 and the chopper 25. By the above welding method, during welding, it was possible to suppress the width of the carbide precipitation castle at 800 to 500° C. in the heat-affected zone from widening due to fluctuations in welding conditions. The width of the temperature distribution zonal curve and the fluctuation state of the fluctuation band recorded during welding were used during welding inspection, and used to determine whether the welded product is susceptible to corrosion cracking due to intergranular corrosion during use. Welded parts of stainless steel pipes require periodic inspection when used in a window environment. Therefore, the recorded data was used to determine key points to be inspected during periodic inspections and used for maintenance management of welded objects. As described above, the present invention measures the width of the temperature distribution in a direction perpendicular to the welding direction of a welded part in a continuous band-like temperature distribution in a certain degree range, and utilizes it for maintenance management of the welded part or welding control. .

The latter allows for a welding method that minimizes the width of the temperature range that has a window effect on welding. The recorded distribution curve can be used for a welding inspection after welding is completed, and can be used to determine whether or not welding was performed correctly or if there was an abnormality. Furthermore, it is possible to classify correctly welded parts and improperly welded parts, and it can be used to judge the health of the weld heat affected zone. It can also be used for periodic inspections, investigating the cause of accidents, and is effective in preventing defective products and welding accidents.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a welded part, Fig. 2 is an explanatory diagram showing an example of a conventional temperature measurement method, Fig. 3 is a configuration diagram of an apparatus for explaining an embodiment of the present invention, and Fig. 4 is a diagram showing an embodiment of the present invention. It is a principle diagram of the thermostat used in the example. 1... Material to be welded, 11... Temperature measuring device, 12...
・Temperature recorder, 15... band-shaped temperature castle. Traditional J map Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1 In a method of welding while measuring the temperature of the weld heat-affected area on the surface of the welded material, a temperature measuring device is scanned in a direction perpendicular to the welding direction and a predetermined temperature range in the direction perpendicular to the welding direction is measured in a band shape in the welding direction. A welding method characterized by continuous measurement.