One stretch exceeds the standard
According to different alloys, the tensile resilience characteristics of different specifications of the sheet, set the appropriate amount of stretch, for the high strength, alloying degree of the sheet, after stretching (about 4 days) about one thousandth of the natural rebound Quantity, must be assessed in production. According to the production experience of 45MN stretching machine in China for many years, the empirical calculation formula of the set amount of tensile plate is summarized:
Stretch setting amount = KC (stretching actual length - jaw length) / 1000 + KC (thickness * width / 25000) * 100%
Where K is the elastic modulus of the material, K = 0.6 - 1.0;
C——quenching-stretching interval time coefficient, taking 1.0-1.5;
The tensile setting amount obtained by the above formula can basically satisfy the rescue deformation amount of 1.5%~3.0% required by the stretching process.
2. Participate in profit-making and eliminate improperly
Usually due to uneven holding; the local wave is too large before stretching, the limited amount of stretching is not enough to eliminate the residual stress in the area; the stretching speed is not stable, resulting in a new uneven stress distribution, the sawing process is The size of the ends of the stretched plates at both ends and the sides are too small, so maintaining a good amount of hot rolled plate shape, a standardized stretching process, and proper selection of the sawtooth size are important conditions for achieving good tensile results.
Three stretching process interrupt piece
The tensile process is usually characterized by poor melt quality, internal inclusions, and looseness leading to tensile fractures. The secondary processing rate of hot rolling passes is unreasonable, resulting in uneven deformation of the surface layer and core of the thick plate, resulting in the core. Residual severe as-cast transitional interlayers are seen to cause tensile fractures; tensile fragments are caused by edge defects in hot-rolled sheets, such as cracks and inclusions.
Four stretch slip line
Stretching slip line is due to excessive stretching, and the amount of calendering in the leveling process before stretching is too large (referring to the processing method of calendering straightening); quenching-stretching-quenching-stretching Repeat production.
Article source: www.bombgroup17.com 7075 tensile plate