In order to ensure the welding quality, the welded blade shall be carefully inspected in order to find out the causes of defects and improve them. Before inspection, the blade shall be sandblasted or gently ground to remove the solder and impurities adhered to the blade surface, and cleaned with kerosene. The inspection items and requirements are as follows:

1. Check the weld strength: grind the back of a blade with a green silicon carbide grinding wheel, and check the thickness of the solder layer, which is required to be less than 0.15mm. There shall be no air holes and insufficient solder at the bottom of the tool tip support, and the weld with unfilled solder shall not be less than 10% of the total length of the weld. If there are pores, the blade will fall off during cutting.

2、 Check the position of the blade in the cutter slot: if the dislocation and sagging of the blade exceed the provisions of the technical conditions, re welding shall be carried out.

3、 Check the welding strength: knock the blade with medium force with a wood hammer or red copper hammer, or knock the blade with strong force with an I hammer. At this time, it is qualified if the blade does not fall off from the blade body. Check the welding strength of blades, not necessarily one by one, but also random inspection.

4、 Check the flatness of the blade: if there are obvious pits on the blade, it indicates that the blade is overheated and deformed, and a new blade shall be burned down and re welded.

5、 Check for cracks: after the blade is cleaned with kerosene, if the blade has cracks, kerosene will penetrate into the cracks and appear black lines, which can be observed with the naked eye. It can also be observed with a magnifying glass of 10-40 times.

The color flaw detection method can also be used to check the crack of the blade: use the solution mixed with 65% kerosene, 30% transformer oil and 5% turpentine, and add a little Sudan red. Place the turning tool blade in the solution for 10-15 minutes, then wash it with clean water, apply a layer of clay (kaolin), and observe its surface after baking. If there are cracks on the blade, the color of the solution will be exposed on the clay, which can be seen with the naked eye. Cracked blades cannot be used and need to be re welded.

In addition to the several common car 7J welding methods introduced above, there are also oil protection, electric furnace, forging furnace and brazing in furnace with reducing gas, which will not be introduced in detail here.