According to the tensile retraction characteristics of different alloys and different specifications, set the appropriate pre-stretching amount. For plates with high strength and high supply, there is about one-thousandth of the natural rebound after stretching, which must be considered in production.
2 improper compensation of the residual stress
Usually because of the uneven clamping of each jaw; the local wave is too large before stretching, the limited amount of stretching is not enough to eliminate the residual stress; the stretching speed is not stable, resulting in a new uneven gravitational distribution; sawing The process is too small to cut the both ends of the stretched plate at both ends and both sides. Therefore, maintaining a good hot rolled plate shape/standardized drawing process and correct selection of the sawing size are important conditions for obtaining good tensile results.
3 stretching process interrupt piece
The interruption piece of the stretching process is usually caused by poor melt quality, internal slag inclusion/slacking, etc., resulting in tensile fracture; the secondary processing rate of the hot rolling pass is unreasonable, resulting in uneven deformation of the surface layer and the core of the thick plate, resulting in uneven deformation of the surface layer and the core portion of the thick plate. A severely cast-like transitional interlayer remains in the core, which can cause tensile fragments, which cause tensile fragments due to edge defects such as cracking, cracking, and slag inclusion.
4 stretch slip line
The stretching slip line is due to the excessive amount of stretching; the amount of calendering in the leveling process before stretching is too large, and the repeated production of quenching-stretching-quenching-stretching.