Have you ever wondered to yourself, "Self, what type of metal are these barrels made of?". No probably not, but I have the answer to those questions. The samples below were taken on Niton XL3t GOLDD+. The surface finish was ground off and cleaned and several samples were taken from the same spot to make sure the readings were accurate.
| Yugoslavian RPK (7.62x39)
|
|
Polish AK (7.62x39)
|
|
Egyptian Maadi (7.62x39)
|
| Element
|
Percent
|
+/-
|
Element
|
Percent
|
+/-
|
Element
|
Percent
|
+/-
|
| Chromium (Cr)
|
0.805
|
0.122
|
Chromium (Cr)
|
0.213
|
0.073
|
Chromium (Cr)
|
0.207
|
0.089
|
| Manganese (Mn)
|
0.584
|
0.174
|
Manganese (Mn)
|
0.710
|
0.171
|
Manganese (Mn)
|
0.602
|
0.193
|
| Iron (Fe)
|
96.79
|
0.60
|
Iron (Fe)
|
97.70
|
0.62
|
Iron (Fe)
|
97.91
|
0.67
|
| Copper (Cu)
|
0.310
|
0.141
|
---
|
---
|
---
|
---
|
---
|
---
|
| Molybdenum (Mo)
|
0.053
|
0.015
|
Molybdenum (Mo)
|
0.022
|
.011
|
---
|
---
|
---
|
| Likely Equivalent Carbon (LEC)
|
0.745
|
0.011
|
Likely Equivalent Carbon (LEC)
|
1.29
|
0.01
|
Likely Equivalent Carbon (LEC)
|
1.29
|
0.01
|
| Estimated Alloy
|
5130
|
Estimated Alloy
|
1095
|
Estimated Alloy
|
1095
|
| Russian AK-12 (5.45x39)
|
|
Russian Saiga (7.62x39)
|
|
Romanian 47 (7.62x39)
|
|
Bulgarian 74 (5.45x39)
|
| Element
|
Percent
|
+/-
|
Element
|
Percent
|
+/-
|
Element
|
Percent
|
+/-
|
Element
|
Percent
|
+/-
|
| Chromium (Cr)
|
1.14
|
0.15
|
Chromium (Cr)
|
0.181
|
0.086
|
Chromium (Cr)
|
0.227
|
0.100
|
Chromium (Cr)
|
0.171
|
0.070
|
| Manganese (Mn)
|
0.533
|
0.191
|
Manganese (Mn)
|
0.808
|
0.216
|
Manganese (Mn)
|
0.748
|
0.222
|
Manganese (Mn)
|
0.604
|
0.162
|
| Iron (Fe)
|
97.18
|
0.85
|
Iron (Fe)
|
97.47
|
.078
|
Iron (Fe)
|
97.61
|
0.85
|
Iron (Fe)
|
97.41
|
0.56
|
| ---
|
---
|
---
|
Zirconium (Zr)
|
0.038
|
0.018
|
---
|
---
|
---
|
---
|
---
|
---
|
| Molybdenum (Mo)
|
0.245
|
0.032
|
Molybdenum (Mo)
|
0.022
|
.011
|
Molybdenum (Mo)
|
0.032
|
0.015
|
---
|
---
|
---
|
| Likely Equivalent Carbon (LEC)
|
0.605
|
0.011
|
Likely Equivalent Carbon (LEC)
|
1.29
|
0.01
|
Likely Equivalent Carbon (LEC)
|
1.29
|
0.01
|
Likely Equivalent Carbon (LEC)
|
1.29
|
0.01
|
| Estimated Alloy
|
4140
|
Estimated Alloy
|
1095
|
Estimated Alloy
|
1095
|
Estimated Alloy
|
1095
|
Here are common elements that are added to steels and the properties they add.
| Element
|
Typical Range (%)
|
Principal Effects
|
| Aluminum (Al)
|
< 2
|
Aids nitriding; restricts grain growth.
|
| Sulfur & Phosphorus (S, P)
|
< 0.5
|
Improves machinability but reduces weldability, ductility, and toughness.
|
| Chromium (Cr)
|
0.3–4
|
Improves corrosion and oxidation resistance, hardenability, and high-temp strength; forms hard carbides.
|
| Nickel (Ni)
|
0.3-5
|
Promotes austenitic structure, improves toughness, mildly increases hardenability.
|
| Copper (Cu)
|
0.2-0.5
|
Enhances corrosion resistance by forming a protective oxide film.
|
| Manganese (Mn)
|
0.3-2
|
Increases hardenability, lowers hardening temperature, and counteracts sulfur’s brittleness.
|
| Silicon (Si)
|
0.2-2.5
|
Acts as a deoxidizer in steelmaking and increases toughness.
|
| Molybdenum (Mo)
|
0.1-0.3
|
Enhances hardenability, grain refinement, and high-temperature strength.
|
| Vanadium (V)
|
0.1-0.3
|
Promotes grain refinement, increases hardenability, forms wear-resistant carbides.
|
| Boron (B)
|
0.0005-0.003
|
Very small amounts significantly increase hardenability.
|
| Lead (Pb)
|
< 0.3
|
Added for improved machinability (does not strengthen).
|
| Nitrogen (N)
|
< 0.1
|
Acts like carbon in strengthening.
|
| Likely Equivalent Carbon (LEC)
|
---
|
An estimate of a steel's hardenability based on its carbon and alloy content.
|
| Zirconium (Zr)
|
0.01-0.10
|
Improves steel's toughness and ductility by refining grain size and controlling non-metallic inclusions.
|
Zirconium (Zr) improves steel's toughness and ductility by refining grain size and controlling non-metallic inclusions.
