General Information for Steel 4140
| Material Group |
P-Steel |
| Sub-Grou |
Low Alloy Steel |
| Tensile Strengt |
740-1080[N/mm^2] |
| Machinability |
70% |
MACHINABILITY OF 4140 STEEL
SAE 4140 is chromium-molybdenum steel produced with 0.15–0.25% of molybdenum, and 0.80–1.10% of chromium content. It has high hardenability; good fatigue, abrasion, and impact resistance; and can be nitrated for maximum wear and abrasion resistance. 4140 Steel is used where fatigue, abrasion, and impact resistance are needed. 4140 steel is used for high-strength machine parts such as connecting rods, crankshafts, steering knuckles, axles, pump parts, gears, and pinions. It is also used in the production of cutting tools.
The hardness of these steels depends on the heat treatment:
195 HB- Anealed.
240-300 HB- Normalized.
230-340 HB- Quenched
The average machinability rating of 4140 steel is 70% (Annealed condition)
SUMMARY:
For turning operations on steel 4140, it is best to use inserts with thick CVD coating and medium hardness. For milling, any all-around carbide grade is suitable.
For detailed carbide grades recommendations, check the table below.
Recommended Cutting speed range for turning at stable conditions is 850 - 1160 [SFM] / 260 - 355 [m/min].
Recommended Cutting speed range for milling with stable clamping and short over hang is 520 - 720 [SFM] / 160 - 220 [m/min]
For detailed cutting speed recommendations,check the table below.
Equivalent International Designations for Steel 4140
| Standard |
Name |
| SAE |
4140 |
| WNR |
1.7225 |
| DIN |
42CrMo4 |
| BS |
708M40 |
| SS |
2244 |
| ANFOR |
42CD4 |
| UNI |
42CrMo4 |
| UNF |
42CrMo4 |
| JS1 |
SCM440(H) |
Chemical Composition for Steel 4140
| Element |
Amount |
| Chromium(Cr)) |
.80-1.10% |
| Manganese(Mn) |
.75-1.00% |
| Carbon(C) |
.38-.43% |
| Molybdenum(Mo) |
.15-.25% |
Cutting Speeds Recomendations for Steel 4140
| Application |
Vc (m/min) |
Vc (SFM) |
| Turning |
260-355 |
850-1160 |
| Milling |
160-220 |
520-720 |
| Parting |
125-170 |
410-560 |
| Grooving |
145-200 |
480-660 |
| Drilling |
105-140 |
340-460 |
Important! The speed estimation is given for an ideal situation:
- Most suitable carbide grade
- Stable tool clamping
- Stable workpiece clamping
- Good quality raw material
- A short overhang of the cutting tool.
- Nominal hardness of the material.
- etc.
Recommended Carbide Grades for Steel 4140
Grade for Milling (Indexable)
Recommended Insert Cutting Edge Geometry for Steel 4140
| Honing Siz |
0.05-0.08 mm / 0.002-0.003" |
| Rake Angl |
11° -13° |
| Land Angl |
Positive |
| Land Widt |
0.20-0.30 mm / 0.008-0.012" |
