The issue of material strength
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I would like to ask everyone: for materials with the same composition, such as steel plates, steel pipes, and forgings, their strengths vary. What is the reason for this? For example, in the case of 12Cr1MoV, the standard strength value for steel plates differs from that of steel pipes, and it is also different from that of forgings. The allowable stress also varies when creep is not taken into account (below 500°C). Why is that?
12Cr1MoVR, 12Cr1MoVG, 12Cr1MoV. ?, name, standards, manufacturing, delivery, composition, thickness, and so on.
The standard number for 12Cr1MoVR is GB/T713-2017 \"Steel plates for boilers and pressure vessels\", which stipulates that the standards must be followed； The standard number for 12Cr1MoVG is GB5310-2008, \"Seamless steel tubes for high-pressure boilers\", which stipulates that the standards must be followed ； 12Cr1MoVNB/T47008 \"Forgings of carbon and alloy steels for pressure equipment\"
First of all, these allowable stresses are all measured values. If the material is continuous and uniform under ideal conditions, there should be no difference. In reality, however, due to the different methods used for manufacturing sheets, pipes, and forgings, the ability to control the internal quality of the material varies, which in turn results in differences in the material’s actual mechanical properties.
However, for steel plates themselves, the standard values for their strength vary depending on the thickness; the thicker the plate, the smaller its rolling ratio, and the poorer its performance. There are certainly differences in performance among different types such as plates, tubes, and forgings.
Due to different manufacturing processes such as forging, rolling, and drawing, the direction of deformation of the fibers in the material’s internal structure varies