Ways to avoid welding cracks in large-size cemented carbide-2

       3 　Improve the welding method

For the above reasons, through analysis, the welding method, welding

Process control and post-welding treatment have been improved, and the welding surface structure

It has been improved, and the processing equipment and processing methods have been improved in the finishing process.

Line optimization, through the process design of the whole process system, reprocessing

10 products, the qualified rate of the product reaches 100%, which is a good solution

Solve the problem of welding cracks between large-size cemented carbide and steel substrate.

Refer to Figure 2 for the schematic diagram of the connection part. The specific improvements are as follows:

(1) Preheat before brazing, the temperature is generally 200 ℃ ~ 800 ℃;

(2) Silver-based brazing is used to reduce the welding temperature, and the brazing filler metal is used

HL303, the flux adopts QJ102, and the welding temperature is generally 730 ℃

～ 800 ℃;

(3) Add a material pool to the welding plane of the substrate to facilitate the preset solder

And flux to ensure that the solder is easy to fill during welding, thus shortening the time

Heating to reduce solder overflow;

(4) <11 Unilateral clearance adjustment between centering part and alloy inner hole

It is 0 1 25 ～ 0 1 30mm. During the welding process, there is no welding here, but the end face

It is sufficient if the solder part overflows. Thereby eliminating the free shrinkage of the extrusion surface of the matrix to the alloy;

(5) High-frequency welding is used to shorten the long welding time and ensure

Uniformity and rapidity of heating;

(6) Compensation copper sheet is added to the welding surface, with a thickness of 0 1 4 ～ 0 15 mm, used for

Absorb shrinkage stress;

(7) Rough machining of the alloy before welding;

(8) Improvement of cooling method after welding, because resistance furnace generally has no cooling

But the speed is displayed, and the workpiece can only be cooled with the furnace after being put in, the cooling time

It will be too long. In order to control the cooling rate, the boron

Heat the sand to 240 ℃～280 ℃ and take it out, then put the soldered product into the

In the heated borax, ensure that the product is cooled to the room within 3 to 4 hours

temperature.