Home   >   Blog

Rockwell B to C Hardness Conversion Chart

In this blog post, you’ll read:While the Rockwell hardness testing scale is prevalent, it is best to consider the material thickness and softness to select the most suitable scale between Rockwell B (HRB) and Rockwell C (HRC). This article compares two types of Rockwell hardness to help you find the most ideal of the two for your hardness testing and conversion needs.

Table of Contents

The design and manufacture of metallic components require that designers specify the hardness of the metal parts. However, designers often have difficulty deciding what hardness scale to use in their specifications. Most designers try to convert their hardness testing scales to more suitable ones like Rockwell hardness B and C scales. This article compares two types of Rockwell hardness to help you find the most ideal of the two for your hardness testing and conversion needs. 

 

Rockwell B to C Hardness

I. What is Rockwell Hardness B?

Rockwell hardness testing method is widely accepted in many industries with different scales. The Rockwell hardness B scale has more accuracy when testing soft metals like brass, aluminum, and mild steel. Its use often involves an indenter with a known shape and load to cause a depression that is measured to ascertain the hardness of the material. Further, it uses a steel ball hardened to have a more indentation effect on the material. The ball’s weight is usually 100kg, and its hardness value is identified with HRB.

Related Article: Rockwell B Scale

 

II. What is Rockwell Hardness C?

With an indenter with a diamond tip and a cone shape, the Rockwell hardness C uses a weight of 150kg to cause a measurable depression on the material surface, which gives the material hardness. However, Rockwell hardness C is more suitable for harder materials and, as such, is often applicable to testing materials that include hard steel. HRC is used to measure the hardness value for Rockwell scale C, and it helps to identify it when converting it to other hardness scales. 

 

III. Which is Harder Rockwell C or B?

When deciding the hardness testing scale to use between Rockwell hardness C and B, it is often best to confirm the material’s hardness or softness and thickness. This information helps to determine which is more suitable for testing the material. However, the Rockwell hardness scale C is harder than B and unsuitable for thin and soft materials like aluminum and brass. It is often used for harder and very thick materials like hardened steel. 

 

IV. What is the Difference between Rockwell B and C?

Some differences make the Rockwell B and C hardness scale suitable for specific uses. Some of these differences are obvious, and others are not. The indenter types are one of the apparent differences as Rockwell hardness B uses a hardened ball made of hardened steel while the Rockwell C scale uses a cone-shaped indenter with a diamond tip. Also, the weights of the indenters used are pretty different as type B indenter ball weighs 100kg while type C weighs 150kg. Furthermore, they are used for different levels and thicknesses of material samples.

 

V. Can you Convert HRB to HRC?

Converting hardness Rockwell B (HRB) to hardness Rockwell C (HRC) is a usual practice for many designers when specifying the hardness value of a material. This conversion is possible using charts and tables calculated using formulas to get approximate but acceptable values that can be interchanged for the different Rockwell hardness testing scales.

 

VI. Rockwell B to C Hardness Conversion Chart

Rockwell Hardness Conversion Table

Rockwell B (HRB)

Rockwell C (HRC)

100kg 1/16″

Ball

150kg

Brale

70

69

68

67

66

65

64

63

62

61

60

59

58

57

56

120

55

120

54

119

53

119

52

118

51

117

50

117

49

116

48

116

47

115

46

115

45

114

44

113

43

113

42

112

41

112

40

111

39

110

38

110

37

109

36

109

35

108

34

108

33

107

32

106

31

105

30

104

29

104

28

103

27

103

26

102

25

101

24

100

23

99

22

98

21

97

20

96

18

95

16

94

15

93

13

92

12

91

10

90

9

89

8

88

7

87

6

86

5

85

4

84

3

83

2

82

1

81

0

Conclusion

In conclusion, identifying the best hardness testing scale to use will depend on the level of hardness testing of the material. While the Rockwell hardness testing scale is prevalent, it is best to consider the material thickness and softness to select the most suitable scale between Rockwell B (HRB) and Rockwell C (HRC). This will ensure the accuracy of the result of the hardness testing value. 

Related Article: HRC to Vickers Hardness Conversion Chart

Related Article: Rockwell C to Brinell Hardness Conversion Chart