1, the material strength reduction is more obvious, due to the burned area of the cross-section weakened as well as stress concentration and other factors, leading to the material in the lower stress on the hair on the fracture. Severe burned material, the breaking strength may be below the yield point.
2. The burned area becomes hard and brittle, which is very unfavorable for cold working.
3, the burned place may produce cracks, resulting in material damage similar to low-stress brittle fracture. (That is, the fracture surface of the hole pit is not obvious)
4, from the surface alone to see the size of the burns, and can not judge his degree of damage to the material. Sometimes it does not look serious, the lack of serious impact on the experimental results, and sometimes it looks like there will be an impact, in fact, but not significant. I guess it has to do with the nature of the material itself, or with the specific circumstances at the time of the burn.
On the whole, the steel used in construction has a low carbon content, and the effect of strength after scorching is not very terrible, coupled with the structural design of the affluent, and thus the impact is limited. However, individual examples show that the strength effect after scorching is large. Therefore, as far as possible, do not fire the arc on the main bar to prevent flash butt welding electrode contact burns, the code has relevant provisions.
For reference only.