Grey Cast Iron And Permanent Deformation
Grey Cast Iron And Permanent Deformation
(OP)
Hello.
I have seen a number of stress-strain curves for grey cast iron indicating permanent deformation after application and removal of a load. In all of the instances I have seen, however, the first load application gives rise to a stress that is some significant proportion, say 40% or more, of the UTS of the material.
What I should like to know is whether there are lower stress regions where all of the strain is recoverable for grey iron.
Thanks.
I have seen a number of stress-strain curves for grey cast iron indicating permanent deformation after application and removal of a load. In all of the instances I have seen, however, the first load application gives rise to a stress that is some significant proportion, say 40% or more, of the UTS of the material.
What I should like to know is whether there are lower stress regions where all of the strain is recoverable for grey iron.
Thanks.





RE: Grey Cast Iron And Permanent Deformation
"Steel shows a rather minor influence of tensile strength and hardness on the modulus of elasticity, since it is mostly in the range of 29,000,000 to 30,000,000 psi. For gray iron, the modulus of elasticity not only varies with tensile strength but also with the stress level. As a result of these factors, the modulus of elasticity will vary from around 12,000,000 psi for a very soft iron to over 20,000,000 psi for a high strength iron. The stress-strain curve for gray iron in tension is almost a curved line from the origin. This has been reported by many investigators, and Morrogh[14], in reporting some work by Gilbert, suggests that the curve is a result of some volume changes in the spaces occupied by the graphite. They have also shown that some microcracking takes place between flakes. Some investigators have used resonant frequency measurements and also sound velocity measurements which are dependent on modulus of elasticity to predict tensile strength."
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RE: Grey Cast Iron And Permanent Deformation
RE: Grey Cast Iron And Permanent Deformation
I think the "...secant modulus is a conservative value suitable for most engineering work; design loads are seldom as high as one-fourth the tensile strength, and the deviation of the stress-strain curve from linearity is usually less than 0.01% at these loads..." quote has largely allayed the practical concerns that I had.
The ASM handbook to which you refer may well be the source of information that I am after. I have looked at the ASM website, and I see that this volume covers steels and irons. In the past I have found that such publications tend to be weighted 95:5 in favour of steels information, which may prevent me from asking my boss to purchase it! Assuming you are familiar with it, could you please give an indication as to how much information there is directly related to irons rather than steels. Thanks.
RE: Grey Cast Iron And Permanent Deformation
RE: Grey Cast Iron And Permanent Deformation
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