what is SI unit of toughness and ductility?
955533
Fracture toughness  \nUnit Name Symbol SI Equivalent  \n· ksi-sqrt(inch)  \n ksi-sqrt(in)  1.09884x106 Pa-sqrt(m)  \n· MPa-sqrt(meter)  \n MPa-sqrt(m)  1x106 Pa-sqrt(m)  \n· Pa-sqrt(meter)  \n Pa-sqrt(m)  1 Pa-sqrt(m)  \n· psi-sqrt(inch)  \n psi-sqrt(in)  1098.84 Pa-sqrt(m)
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Within the elastic limit of any material it is seen that the stress in the material is directly proportional to the strain. \nHence the constant for the proportinality is called Youngs Mdulus (E). The unit of Youngs Modulus is N/mm^2 or MPa(Mega Pascals) or PSI(Pounds per sq. inch) same as the unit of stress.\n\nAlso it may be referred as Stress/Strain= Youngs Modulus.\n\nUsage of youngs modulus:\n----------------------------------\nStress is not a straight measurable quanitity, but engineers are very curious to evaluate stresses in a loaded material to check if it can withstand the design load or applied load. Strain is a measurable quantity (strain gages can measure strains) and once strain is measured the stress can be deduced by multiplying with the youngs modulus.
438539
You should find that under the ASTM Manual for steel. Your engineering department should have a copy, otherwise try finding it on line.
1140224
There are literally thousands of grades of steel out there. Each one having different properties including tensile strength, carbon content, etc.  If you are wanting to know about a certain application, its best to consult an engineer. If you are just wanting to learn a little about it, just get a book about engineering materials.
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SI is an abbreviation of Système International d'units , a French word meaning International System of Unit. \nIn English, they are spelled as System(e) International(e) with the ones in parantheses being optional (or merely some people add them unconciously, and others forgot to supply them)\n\nSee source fo further information.
966327
I agree; c) is the right choice.  The other units are used to measure:\n\na)  power ratio\nb)  pressure\nd)  pressure (again)
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newton (N)\ndyne (dyn)             10.0 µN \ngrain-force (grf)            635.4602 µN \ngram-force (gf)          9.80665 mN \npoundal (pdl)        138.2550 mN \nounce-force (avdp) ozf        278.0139 mN \npound-force (lbf)      4.448222 N \nkilogram-force (kgf)      9.80665 N \nkilopond (kp)      9.80665 N \nsthène (sthène)  1.0 kN \nkip (= 1 000 lbf) (kip)  4.448222 kN \nUS ton-force (= 2 000 lbf) (short) tonf (US)  8.896443 kN \ntonne-force (= 1 000 kgf) (metric) tf  9.80665 kN \nUK ton-force (= 2 240 lbf) (long) tonf (UK)  9.964016 kN
947911
here is an excerpt from the following source:\n\nhttp://chemistry.about.com/b/a/000855.htm?terms=spider+silk\n\n\nHollow nanofibers spun from a carbon/polymer composite are tougher than Kevlar, steel, or spider silk. 'Toughness' is a term used to describe the ability of a substance to absorb mechanical energy before breaking. Go to Science News to read their article on the nanotubes.
1071611
The 30 in the HV30 stands for the 30 kgf force used in the hardness test
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GPa and MPa (giga-pascal [1E9 pascals] and mega-pascal [1E6 pascals])  are metric units of stress. (6.89 Mpa = 1 ksi [1000 psi - pounds per square inch])(1 Pa = 1 newton / meter^2)\n\nUsually fibers are tested in 'tows' bundles of maybe 1000 fibers. In order to know what force they can sustain given a tensile strength you just multiply the tensile strength by the cross-sectional area of the fibers.
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Physical:\nLight and strong material. \n\nChemical:\nCorrosion resistant. Soluble in some acids. Has a high melting point.
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Strength of materials\n\n\nIt has been suggested that Tensile strength be merged into this article or section. (Discuss)\nStrength of materials is the scientific area of materials science for the study of the strength of engineering materials and their mechanical behavior in general (such as stress, deformation, strain and stress-strain relations). Strength is considered in terms of compressive strength, tensile strength, and shear strength, namely the limit states of compressive stress, tensile stress and shear stress
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Density(g/cm3) Steel Grade \n7.93 201,202,301,302,304,304L,305,321 \n\n7.98 309S,310S,316,316L,347 \n\n7.75 405,410,420 \n\n7.70 409,430,434 \n\nThere are some familiar Density of stainless steel above. Wish it be helpful.
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i think you can get a lot of this info rmation to clerar your doubts\n\nhttp://www.calce.umd.edu/general/Facilities/Hardness_ad_.htm
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http://en.wikipedia.org/wiki/Strength_of_materials
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International Units. These units would be standardized measurements for the amount of a substance -whatever it is they refer to. They are things like vitamins and such that require both a qualitative and quantitative measurement to have meaning. An excellent description is referenced below.
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If it's a property of a metal, it's referring to the metal's ductility.  Metals like silver and copper have a high ductility - meaning they can be drawn into wires by a mandrel quite easily.  Titanium has a very low ductility - meaning the metal will tend to break if drawn.