Chromium is a hard, brittle metal used mainly as an alloying agent in stainless steels, heat-resistant alloys and in titanium alloys. Chromium is also widely used for plating purposes because of its excellent corrosion resistance, due to a thin surface oxide layer.

Typical Analysis:

              Process           Al       C       Cr       Fe      N        O         P      Si        S

              Electrolytic:    0.015   0.05   99.50   .035    0.02    0.05     0.01    0.04    0.01

           Aluminothermic: 0.10    0.05   99.40   0.20    0.02    0.10     0.01    0.10    0.01

Structure:

Above 1840 ^oC: face-centered cubic; a=0.3 nm.

Mass Characteristics:

Atomic Weight: 51.996

Density: 7.19 g/cm³ at 20 ^oC

Thermal Properties:

Melting Point: 1875 ^oC

Boiling Point: 2680 ^oC

Phase Transformation Temperature: 1840 ^oC

Coefficient of Linear Thermal Expansion: 6.2 µm/m ⋅ K

Specific Heat: 0.4598 kJ/kg ⋅ K at 20 ^oC

Latent Heat of Fusion: 258 to 283 kJ/kg

Latent Heat of Vaporization: 6168 kJ/kg

Thermal Conductivity: 67 W/m ⋅ K at 20 ^oC, 76 W/m ⋅ K at 426 ^oC, 67 W/m ⋅ K at 760 ^oC

Entropy:                                                                                                    

                                           Entropy, kJ/kg ⋅ K

              Temp (^oC)          Solid                    Gas 

                25                    .046                     3.35 

               227                    0.71                     3.56 

               727                    1.09                     3.83 

              1227                   1.36                     4.00 

              1727                   1.59                     4.13 

              2227                   4.24 

              2727                   4.31

                  ^oC                       Pa 

              965                3.2 x 10⁴ 

              1093               2.8 x 10³ 

              1197               2.7 x 10²

              1288                2.4 x 10¹ 

              1875                9.9 x 10² 

Electrical Properties:

Electrical Conductivity: 13% IACS at 20 ^oC

Electrical Resistivity:

              ^oC                       nΩ ⋅ m 

            -260                        5

              20                        130

              152                      180

              200                      200

              407                      310

              600                      400

              652                      470

              1000                    600

Temperature Coefficient of Electrical Resistivity: At 0 ^oC, 0.03 nΩ ⋅ m per K

Electrochemical Equivalent: Valence 3, 0.17965 mg/C; valence 6, 0.08983 mg/^oC

Electrolytic Solution Potential: For valence 3,0.5 V versus hydrogen electrode

Hydrogen Over-voltage: 0.38 V

Temperature of Superconductivity: 0.08 K

Work Function: 0.7337 aJ

Magnetic Properties:

Magnetic Susceptibility: Volume: 4.5 x 10^-5 mks

Optical Properties:

Color: Steel gray

Reflectance:

67% at λ = 300 nm

            63% at λ = 1000 nm

            70% at λ = 500 nm

            80% at λ = 4000 nm

Refractive Index: 1.64 to 3.28 for λ from 257 to 608 nm

Absorptive Index: 3.69 to 4.30 for λ from 257 to 608 nm

 Nuclear Properties:

Stable Isotopes: ⁵⁰Cr, 4.31% abundant; ⁵²Cr, 83.76% abundant, ⁵³Cr 9.55% abundant, ⁵⁴Cr 2.38% abundant.

Unstable Isotopes:

              Isotope Number                              Half-life

                     48                                            23-24 h

                     49                                         41.7 - 41.9 min

                     51                                         27.5 - 27.9 days

                     55                                          3.52 - 3.6 min

                     56                                              5.9 min

Chemical Properties:

Resistance to Specific Corroding Agents: (A 10% solution at 12 ^oC was used unless otherwise noted.) Chromium is resistant to the following acids: acetic, aqua regia, benzoic (saturated), butyric, carbonic, citric, fatty, formic, hydrobromic, hydroiodic, lactic, nitric, oleic, oxalic, palmitic, phosphoric, picric, salicylic, stearic, and tartaric. Chromium is not resistant to hydrochloric acid or other halogen acids.

Chromium is Resistant to the Following Agents: Acetone, air, ethyl and methyl alcohol, higher alcohols, aluminum chloride, aluminum sulfate, ammonia, ammonium chloride, barium chloride, beer, benzyl chloride,(saturated and 100%) calcium chloride, carbon dioxide, carbon disulfide, carbon tetrachloride (saturated and 100%), dry chlorine, chlorobenzene (saturated and 100%), chloroform, copper sulfate, ferric chloride, ferrous chloride, foodstuffs, formaldehyde, fruit products, glue, hydrogen sulfide (100%), sulfur dioxide (100%), chlorinated water, distilled water, rainwater, zinc chloride, and zinc sulfate. 

Mechanical Properties:

Tensile Properties (For Re-crystallized, Swaged, and Arc Cast Electrolytic Chromium):

                       Tensile                                    Elongation    Reduction      Modulus of

                     Strength,      Proportional      in 25 mm,       in Area,        Elasticity,

  ^oC                    Ma             Limit, MPa              %                  %                  GPa

 20                     83                   __                       0                   0                    248

200                   234                   __                       0                   0                    __

300                 154(a)                11.7                     3                   4                   290

350                  197                   105                      6                   8                   168

400                 225(b)               132                      51                 89                  227

500                  __                    __                        30                 75                   __

600                 242                   69                        42                 81                  200

700                 203                   __                        33                 85                   __

800                 180                   97                        47                 92                  255

Recrystallized at 1200 ^oC in hydrogen. Strain rate of testing, 0.017 m/m per min. (a) Yield strength, 131 MPa. (b) Yield strength 140 MPa.