Excavator bucket material and its weldability
Under high temperature, the Tansiango martensite structure has good toughness and has high abrasion resistance due to surface layer hardening under impact load. But the weldability of this steel is poor: one is that the carbide in the weld heat affected zone precipitates The embrittlement of the material, the other is the weld produces the hot crack, especially in the near seam area.
1, the heat affected area precipitates the carbide to cause embrittlement
ZGMn13 Manganese steel may precipitate carbide along the grain boundary when it is heated more than 250 ℃, which greatly reduces the toughness of the high manganese steel and seriously damages its excellent performance. After analysis, when the high manganese steel is reheated again and the cooling speed is faster, the carbide precipitates first in the grain boundary, and with the prolonging of residence time, the grain boundary carbide will change from discontinuous particle state to reticular distribution, and its brittleness increases obviously. Therefore, when the high manganese steel in welding or welding after the heating, it will be in the welding heat affected zone of different degrees of precipitation of carbide, and may change to martensite, not only make the material brittle, but also reduce its wear resistance and impact toughness. Furthermore, the longer the stay time in the temperature range (650 ℃ or so), the more carbide precipitates in the heat-affected zone.
In order to reduce the precipitation of carbide and to prevent the loss of toughness and brittle, measures should be taken to speed up the cooling, that is, to shorten the stay time at high temperature. To this end, the excavator bucket and bucket teeth welding should be used short section welding, intermittent welding, bubble water welding and so on.
2. Welding hot crack
The method of preventing thermal cracking is to reduce the content of S and p in basic metal or welding material, and to reduce the welding stress by means of welding process, such as short section welding, intermittent welding, dispersed welding and hammering after welding. When surfacing the high manganese steel on the bucket body, it is possible to weld a layer of NI, cr-ni-mn or cr-mn austenitic steels as the isolation weld to prevent cracks.