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Materials and Results

The degree of hardness depends on the chemical analysis of the metal, with carbon being the principal controlling element. When heating and quenching rates are accurately controlled, any ferrous material which can be furnace hardened can be flame hardened to a higher degree of hardness. In choosing a material, availability, cost, hardness and machinability are factors to consider. Our technical staff can advise and discuss specific applications.Effects of flame hardening on steel and iron

Steel/Iron Type Hardness, Rockwell C
1020 mild steel
8620 carburised
1045
30 – 40
62+
55 – 60
1145*
1060
4140
55 – 60
62+
52 – 58
4150
6150
52100
58 – 62
58 – 62
55 – 62
Hardenable martensitic stainless steel
Pearlitic cast iron
(Ductile and grey)
50 – 60
50 – 60

* Fatigue proof, stress proof

Hardness range of plain carbon steels
Carbon Steels Hardness Range (Graph)
Typical hardness curve for flame hardened medium carbon steels.
Carbon Steels Hardness Curve (Graph)

Metal hardness conversion numbers (approx)

Rockwell C Scleroscope 10mm Steel Ball (HB)
66
65
64


701
86
671
63
62
61
84
82
81
656
642
628
63
62
61
84
82
81
656
642
628
60
59
58
80
78
77
613
600
584
57
56
55
76
74
73
574
561
548
54
53
52
71
70
69
536
524
512
51
50
49
67
66
65
500
488
476
48
47
46
63
62
61
464
453
442
45
44
43
59
58
57
430
419
408
42
41
40
56
54
53
398
387
377
39
38
37
52
51
50
367
357
347
36
35
34
48
47
46
337
327
318
33
32
31
45
44
43
309
301
294
30
29
28
42
41
40
286
279
272
27
26
25
39
38
37
265
259
253
24
23
22
36
36
35
247
241
235
21
20
34
33
230
220