HP295 steel plate is usually used to make cylinders for liquefied petroleum gas and dissolved acetonitrile gas. The production process of welded gas cylinders is relatively complicated, mainly composed of two processes: drawing and welding. During the processing, there are often phenomena such as punching, shrinking, and breaking, and the quality of the cylinder is directly related to the user's life and property. Safety. This puts forward strict requirements on the properties of HP295 hot-rolled steel coils (plates) used to make such cylinders, that is, HP295 hot-rolled steel plates not only need to have a certain strength and plasticity, but also have a lower brittle transition. temperature and good formability and weldability.
In the temperature range of 500~1100℃, the area shrinkage rate of HP295 steel plate is above 77%, showing good high temperature thermoplasticity. At 700~900℃, there is a "plastic groove" in the thermoplastic curve of HP295 steel plate, when the deformation temperature is 750 and 800℃, the plasticity is relatively low.
In the test temperature range, the tensile strength of HP295 steel plate generally decreased with the increase of temperature, from 261 MPa at 500 ℃ to 62.33 MPa at 1100℃.
In the temperature range of 900~1100℃, the fracture mode of HP295 steel plate is transgranular ductile fracture, the section shrinkage rate is large, and the plasticity is good; while the temperature of 750~850℃ is in the ferrite and austenite two-phase region of the experimental steel, The grain size in the two-phase region is not uniform, and the cracks occur at the ferrite and austenite grain boundaries and within the ferrite grains. The cracks are easy to initiate and expand. The fracture mode is intergranular ductile fracture, and the plasticity is relatively low.
In the actual production process of HP295 steel plate, the low plasticity temperature range should be avoided, straightening should be carried out when the surface temperature of the slab is higher than 900℃, and the final rolling temperature should be avoided between 750 and 850℃.
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