A, machinery parts, parts processing process welding crack formation mechanism of the sword

1 on cemented carbide heating effect formed crack

Hard alloy blades and steel (knife) thermal expansion coefficient of large difference, but also the thermal conductivity alloys blade material, if the welding rapid heating will produce great stress, prompted blade in welding layer heat stress to split blade.

Therefore welding temperature control in more than 30 ° ~ solders soluble 50 ° c. Selection of the melting solders should be less than 60 degrees, the melting point tool rod welding shall be made of fire uniform heat slowly, so the welding preheat the groove welding surface consistent with the blade. Local overheating will make with the knife blade itself or blade of large temperature difference and thick blade (more serious), thermal stress will make the blade. So the requirement of knife when preheating preheating, if the blade and pole tool rod should be back around with heating heating, this move flame can avoid heat concentrated caused local overheating and crack.

2 the groove shape of crack formation

Mechanical parts, components in machining process of the groove shape and tool rod welding face inconsistency or large difference, the formation of the closed or semi-enclosed groove welding face, too, because of excessive and welding layer after thermal shrinkage, also is in the welding stress caused by blade, split. In the use of welding required under the required strength and minimize the soldering area

3 for cemented carbide cooling effect of the crack formation

Machinery parts manufacturing, spare parts processing process after welding welding or cooling rapidly cooling and flux dehydration, can make blades generation blowout and crack. So the good water solder. After welding rapid cooling water cannot put, should put in lime, asbestos powder, sand and other cool down. After a slow cooling best at 300 degrees Celsius above 6 hours with heat furnace cooling.

4 the groove bottom to crack defects

Mechanical hardware fittings, spare parts processing process of the blade and the groove, if uneven surfaces are black hemp pit, local inequality, the welding is not planar, causing solders are unevenly distributed, such not only affect weld strength and stress concentration, fracture, therefore, the blade knife blade surfaces, to grind the groove welding surface should be clean.

Cutting groove in the process of cooperation with the blade knife knife out, not more than 0.5 support rod, if the blade knife mm out too pole tool rod or supporting part supporting part is weak, will make the welding process and sustain tension fracture phenomena.

5 to crack formation during heating blades

Ningbo machining process, the blade in brazing copper brazing alloy, not completely fill the gaps, individual appear empty welding, cutting out in the process of the blade, fall off, therefore, thus, the second heat loss, serious Co binder WC, there may be a grain growth.at directly cause blade crack.