摘要(英) |
The
quality of bean-column joint is related to ensure the whole
building’s stress transfer in steel structure. The welded joints
will produce residual stress, blow hole , slag inclusion, hot
cracking and cold cracking problems. This is caused from the
fusion and solidification between welding metal and base metal
when the bean-column joint of skeleton adopts welded joint s in
steel structure.
This research focuses on abnormal fusion of welding work in
construction site. The welder tends to speed-up the welding
fusion by increasing the arc current or welding foreign matter
in order to increase the fusion. This paper simulates the
abnormal fusion in each practical situation, such as base metal,
groove type and selection of fusion foreign matters, and then
adopts the standard operation process to examine test pieces by
manual welding. The 15 test pieces are divided into normal
fusion and increase arc current fusions. We examine them with
six destructive tests includes, Nondestructive Ultrasonic Test
and Tensile Test, Slide Bend Test, Impact Test, Chemical test,
Metallog raphic Test and Micro-specimen Test. At the end, we
record test numbers, taking macro- and micro-observation diagram
to compare the normal and abnormal weldings.
The research results demonstrate that all test results are in
compliance with the regulations, except three normal fusion test
pieces. However, there is at least one examined item not in
compliance with the regulation in the eleven abnormal fusion
tested pieces. The balance of the only one two-electrode tested
piece meets the regulation requirements. The test figures in
impact tests show the best fusion zone’s embrittement with base
metal among other examining items. The tests also prove that the
nondestructive UT Test cannot determine if the there is an
abnormal fusion under the condition of foreign matter and
electrode fuse. Thus, it is an important issue for the
supervisors to effectively manage the abnormal fusion in
construction sites. |