1 . Bucket materials and welding
WY25 excavator 's bucket material for the Q345, the weld is good. Tooth material ZGMn13 ( high- manganese steel ), the high temperature was austenite single phase , good toughness , impact loads in the surface layer due to work hardening and high wear resistance . But this is poor welding of steel : First, heat affected zone material embrittlement caused by precipitation of carbides ; second weld hot cracking , especially in the production of liquefied cracks near the weld zone .
(1 ) heat affected zone of embrittlement caused by precipitation of carbides
ZGMn13 high manganese steel in the heat again, more than 250 ? may precipitate along the grain boundary carbides , and the material toughness declined significantly , serious damage to the excellent performance of high manganese steel . After analysis , when the high manganese steel, heating and cooling speed again when the first grain boundary carbide precipitation , with the residence time , grain boundary carbide particles by the discrete state into a mesh distribution, the brittleness Increased significantly. Therefore, when the high manganese in welding repair or welding after heating , the heat affected zone will be in a section of carbide precipitation in different degrees , and may the martensite transformation , not only the material brittle , and Will reduce the wear resistance and toughness . And , in the heat affected zone of carbide precipitation temperature range easily (650 ? or so) the longer the stay , the more carbide precipitation .
In order to reduce the carbide , to prevent the loss of toughness and brittle materials , should take measures to speed up the cooling rate , that is, reduced residence time at high temperatures . Therefore, when welding with a short section of welding, intermittent welding, welding and other flood damage .
(2 ) welding hot cracking
Way to prevent hot cracks is to reduce the base metal or welding material in the S and P content ; also available from the welding process on measures to minimize residual stresses , such as the use of a short section of welding, intermittent welding, welding and after welding, hammering scattered And so on . Body in the bucket when the high manganese steel surfacing can be the first welding layer Cr-Ni, Cr-Ni-Mn or Cr-Mn austenitic steel weld for isolation to prevent cracks .
2 . Bucket teeth bucket and welding technology
(1 ) welding preparation
First, remove from the bucket body worn bucket teeth , and then fight tooth angle grinder to install Office polished clean, not that there Nigou , rust , and carefully check for cracks and other defects ; in the bucket teeth to be carbon- arc welding Department Gas Paokai the groove and use angle grinder to clean up.
(2 ) the weld
? first bucket body ( with the bucket teeth junction ) with GB E309-15 electrodes for welding , welding electrode is subject to 350 ?, 1 ? 5 h drying , welding current should be relatively large , slightly slower welding speed , To ensure the fusion zone of nickel content of 5% to 6 %, to prevent the generation of the crack -sensitive martensite .
? positioning welding . Tooth assembly in place, with a diameter of 3 ? 2 mm of the D266 electrodes were bilaterally symmetrical position welding, seam length does not exceed 30 mm. Water immediately after welding and hammering .
? bottoming welding . With a diameter of 3 ? 2 mm of the D266 were bottoming welding rod . With a small current, direct current reverse polarity , intermittent welding, a short section of solder . Welding should be stopped every time , water cooling, temperature control between the layers below 50 ? .
? to fill welding . After the end of welding , use the D266 4mm diameter electrode for intermittent welding , welding current of 160A, a sub- electrode welding completed 3 to 4 times , each time stopping welding, the weld cooling water still in time to 50 ? Below, and to hammer , to remove stress and to prevent carbide precipitation ; each weld is completed for about two rotation welding seam welded to ensure the symmetry of up to 16mm up until the welding foot . Each completed a welding inspection with a magnifying glass cracks and, if the crack is used to eliminate carbon arc gouging after welding .
Bucket teeth restored by this method through the use of more than a year , still a good weld . This method fixes Tooth efficient, low cost, good effect, there are some practical value .

Author:  Dongyang City Yate Precision Casting Co., Ltd
website:  www.zjinyate.net
main product: bucket teeth