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Welding the bucket teeth of the excavator in this way will be no problem in another half a year!

Published:

2020-09-21

Every excavator knows that the bucket teeth are an accessory of the excavator. In the excavator operation, the bucket teeth are relatively easy to break. Once a large rock is dug, the bucket teeth will probably break accidentally, so first of all To find a way to repair, usually re-welding the bucket teeth on the bucket body. Welding bucket teeth is not a simple task. We also test the welding skills of the repairman. The following will teach you how to weld the bucket teeth firmly, so that we can weld the excavator bucket teeth for more than a year!

1. The welding place must be cleaned up before welding. It means to remove the original cracked weld meat and grind it with an interphase grinder or use a carbon arc gouging if possible, but the iron oxide must be polished after planing.

2. A certain preheating must be carried out before welding.

If possible, preheat 100 degrees at the welding position. Then use the 3.2J507 welding rod for welding, and the welding will stop after a while, hit the weld and the edge of the weld with a hammer, and keep hitting with a hammer until the weld is basically cooled. The purpose is to relieve welding stress, because it is impossible to do heat treatment after welding.

3. Appropriate welding materials must be selected when welding.

The electrode type is very important. If you want to know what material is, then you have to take some iron foam tests, which will come out after a test, and then distribute the welding rod according to the composition.

4. The welding of the bucket body and the teeth of the excavator must ensure penetration

When welding, the penetration must be ensured. If the gap of the weld position is large, a back plate can be added inside.

2. Excavator bucket material and its weldability

The bucket material of wY25 excavator is Q345, which has good weldability. The material of the bucket teeth is ZGMn13 (high manganese steel), which presents a single-phase austenite structure at high temperatures and has good toughness. It has high wear resistance due to the work hardening of the surface layer under impact load. However, the weldability of this kind of steel is poor: one is the precipitation of carbides in the welding heat-affected zone to cause material embrittlement; the other is that the weld produces hot cracks, especially liquefaction cracks in the near-joint zone.

1. The precipitation of carbides in the heat-affected zone causes embrittlement

When ZGMn13 high manganese steel is heated again above 250℃, carbides may precipitate along the grain boundary, which greatly reduces the toughness of the material and seriously damages the excellent properties of high manganese steel. After analysis, when the high manganese steel is heated again and the cooling rate is faster, the carbides will first precipitate at the grain boundaries. With the extension of the residence time, the grain boundary carbides will change from a discontinuous particle state to a network distribution, and its brittleness A significant increase. Therefore, when the high manganese steel is reheated after welding or welding, carbides will be precipitated to varying degrees in a section of the welding heat-affected zone, and may transform to martensite, which not only makes the material brittle, but also It will also reduce its wear resistance and impact toughness. In addition, the longer the residence time in the temperature range (about 650°C) where carbides are easily precipitated in the heat-affected zone, the more carbides will precipitate. In order to reduce the precipitation of carbides and prevent the material from losing toughness and becoming brittle, measures should be taken to speed up its cooling rate, that is, to shorten the residence time at high temperatures. For this reason, short section welding, intermittent welding, soak welding, etc. should be used when welding the bucket body and the teeth of the excavator.

2. Welding hot cracks

The way to prevent thermal cracks is to reduce the content of S and P in the base metal or welding materials; measures can also be taken from the welding process to minimize welding stress, such as short-section welding, intermittent welding, dispersion welding and post-weld hammering Wait. When surfacing high manganese steel on the bucket body, a layer of Cr-ni, Cr-ni-Mn or Cr-Mn austenitic steel can be welded first as an isolation weld bead to prevent cracks.

3. Welding technology of excavator bucket body and bucket teeth

1. Preparation before welding

First cut off the worn bucket teeth from the bucket body, and then use an angle grinder to polish the place where the bucket teeth are installed. There should be no dirt, rust, and carefully check for cracks and other defects; use carbon arc at the bucket teeth to be welded Gouging out the groove and clean it with an angle grinder.

2. Welding

①First, use GBE309-15 electrode for surfacing welding on the bucket body (joint with bucket teeth). The electrode must be dried at 350℃ for 15h before welding. The welding current should be too large and the welding speed should be slightly slower to ensure the fusion zone. The nickel content is 5% to 6% to prevent the generation of martensite sensitive to cracks.

② Perform tack welding. After the bucket teeth are assembled in place, use a D266 electrode with a diameter of 32MM to perform two-sided symmetrical tack welding, and the length of the weld should not exceed 30MM. Water cooling and hammering immediately after welding.

③ Bottom welding. Use D266 electrode with a diameter of 32MM for bottom welding. Use small current, DC reverse polarity, intermittent welding, short section welding. Water cooling should be timely every time welding is stopped, and the temperature of the interlayer should be controlled below 50℃.

④ Perform filler welding. After the bottom welding is completed, use D266 electrode with a diameter of 4MM for intermittent welding. The welding current is 160A. One electrode is divided into 3 to 4 times to complete the welding. When the welding is stopped, the welding bead must be cooled to 50℃ with water in time. Below, hammering is carried out to eliminate stress and prevent carbide precipitation; every two layers are welded, the left and right welds are alternately welded to ensure the symmetry of the welding until the weld foot reaches 16mm. Use a magnifying glass to check the cracks after each weld. If there are cracks, use carbon arc gouging to eliminate them before welding.

After the above steps, the bucket teeth of the excavator are welded. After more than a year of use, the welds are still intact. The repairing of the bucket teeth is efficient, low-cost, and effective. Not only the repairman can be familiar with it, but also the excavator drivers are worth learning. Yes, to ensure the normal progress of work.

JiangXi ZhiZhong Construction Machinery Co.Ltd

China Excavator Bulldozer Bucket Tooth Supplier Manufacturer

Mobile/Whatsapp/Skype:+86 18146740726

Email:jasontu@jxzzcasting.com

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