CHROMES

Commonly called chrome, the alloy referred to here is actually chromium. Chromium is added to steel in small quantities to improve strength, corrosion resistance and response to heat treatment. At 3% to 10% chromium, steel resists corrosion, but is not actually stainless. At 10.5% to 20% or more chromium, the steel is fully stainless. Chrome, super-chrome and hyper-chrome are steels below the stainless level with increasing chromium content. These metals are used in mildly corrosive environments containing chlorides, carbon dioxide and low hydrogen sulphate concentrations.

Chemical Composition of Common Grades

(Unless otherwise specified in the table, numerical value presents maximum)

Type

Grade

C

Si

Mn

P

S

Cr

Ni

Mo

Cu

V

Other


9Cr

80   ksi

0.09-0.15

1.00   

0.60   

0.020   

0.010   

8.00-10.00

0.25

0.90-1.10

0.25

-

Al   0.04


13Cr

80 ksi

0.18-0.22

0.15-1.10

0.40-1.00

0.020

0.005

12.50-14.00

0.20

0.50

0.20

1.000

-


25Cr

85   ksi

0.025

0.80   

0.80   

0.025   

0.002   

24.00-26.00

8.00   

3.00-4.00

2.00   

-



S13Cr

95/110 ksi

0.030

0.50

1.00

0.020

0.005

11.50-13.50

6.00

1.50-2.50

-

0.500

Ti 0.50


Alloy 28

UNS N08028

0.030   

1.00   

2.50   

0.030   

0.030   

26.00-28.00

30.00-34.00

3.00-4.00

0.60-1.40

-

-















Mechanical Properties of Commonly Strength Levels:

Type

Grade

Yield Strength (min)   
    Rp0.2 Mpa

Tensile Strength (min)   
    Rm Mpa

Elongation (min)   
    A%

Hardness (max.)
    HRC

9Cr

80   ksi

552-655

689

20

22

13Cr

80 ksi

552-655

689

20

22

25Cr

85   ksi

586

814

30

28

S13Cr

95 ksi

655-827

724

20

28

110 ksi

758-965

862

15

32

Alloy 28
    UNS N08028

110 ksi

758-965

793

11

35

125 ksi

862-1034

896

10

37

140 ksi

965-1103

1000

9

38