7Cr17MoV vs 7Cr17 Stainless Steel
7Cr17MoV stainless steel is the Chinese GB standard grade martensitic steel created by adding a little Molybdenum (Mo) and Vanadium (V) to 7Cr17 stainless steel to heighten its wear resistance and hardness.
7Cr17 itself is known as a high carbon Chinese chromium martensitic steel that has a better quenching hardness than 2Cr13 stainless steel. 7Cr17 stainless steel has great hardness and strength under tempering and quenching conditions, and also features excellent corrosion and stainless resistance.
International stainless steel grades that are quite similar to these are the Japanese SUS 440A, and the United States AISI 440A. These particular stainless steels are used mainly for creating high-grade, high-hardness, and high-wearing components like knives and scissors, and also medical equipment. The VICTORINOX swiss army products including their very famous knives and multi-tools, are made out of this particular grade of stainless steel.
7Cr17MoV vs 7Cr17: Chemical Composition Comparison
| Chemical Composition % | ||
|---|---|---|
| Steel Grade | 7Cr17Mov | 7Cr17 (68Cr17) |
| C | 0.60-0.75 | 0.60-0.75 |
| Si (≤) | 1 | 1 |
| Mn (≤) | 1 | 1 |
| P (≤) | 0.04 | 0.04 |
| S (≤) | 0.03 | 0.03 |
| Cr | 16.00-18.50 | 16.00-18.00 |
| Ni (≤) | 0.6 | 0.6* |
| Mo (≤) | 0.75 | 0.75* |
As can be seen from the above table, the two stainless steels are almost identical when their chemical compositions are compared. Note: 68Cr17 is the new designation for 7Cr17.
7Cr17MoV vs 7Cr17: Mechanical and Physical Properties
The chemical properties are very similar between these two stainless steels, so we will now look at both of their mechanical and physical properties as one.
Mechanical Properties
Starting off for steel plate and strip the metal after annealing:
- Elongation: ≥ 15%
- Extension strength: ≥ 245 MPa
- HBW: ≤ 255
- HV Hardness: ≤ 269
- Material HRC Hardness: ≤ 25
- Tensile strength: ≥ 590 MPa
And then for stainless steel bar:
- Material HBW Hardness: ≤ 255 (Annealing)
- Material HRC Hardness: ≥ 54 (Quenched & Tempered)
Physical Properties
Physical properties of a material are used to measure and observe a material without changing the composition of the material. These include: texture, boiling point, density, polarity, appearance, color, melting point, odor and many more. The physical properties of both 7Cr17MoV and 7Cr17 are as follows:
- Coefficients for Linear Thermal Expansion (10-6/K): 10.2 (0-100 ℃); 11.7 (0-500 ℃)
- Density (g/cm3: 7.78
- Electrical Resistivity (μΩ·m): 0.6 at 20 ℃
- Longitudinal Modulus for Elasticity (kN/mm2): 200 at 20 ℃
- Melting Point: 1371-1508 ℃
- Specific Heat Capacity (J/Kg·K): 160 at 0-100 ℃
- Thermal Conductivity (W/m·K): 21.2 at 100 ℃
So what do all of these figures mean to normal people and in easy-to-understand language? Well take a look below and we will run through what all of these properties represent in the real-world:
Corrosion Resistance
7Cr17MoV and 7Cr17 both offer quite good corrosion resistance, due to the amount of Chromium within the metal. They will withstand the test of time and will take longer to corrode and rust than other metals.
Edge Retention (For Knives and Scissors etc.)
Both of these metals again have a decent amount of edge retention. They are not top-of-the-line, but as these materials are generally used for budget knives and scissors, it is satisfactory.
Sharpness
These stainless steels are not very hard metals, so sharpening would not be a very hard task to complete.
Toughness
This is where a metal’s properties that are relative to one another come into play. As both of these stainless steels have great corrosion resistance, and decent hardness, this results in these low-end metals having a low toughness, not the worst, but quite low.
Wear Resistance
Each metal features over 0.5% of Carbon, so it has good wear resistance for any price point, but for a low-end steel, it is great wear resistance for the money.
Applications for 7Cr17MoV and 7Cr17
The one application that these stainless steels are known for above all others are for low-end, budget knives. They are Chinese grade, and are known for their decent performance for the price.
Due to their great corrosion resistance, but not so great edge retention and toughness, they are recommended to be used for kitchen knives, as their longevity is prioritised and not its performance in cutting. If used for hunting or outdoor applications, it is a good idea to bring a sharpening belt or rock with you as you may find yourself with a blunt knife after a short length of time.
Some other applications for 7Cr17MoV and 7Cr17 are:
- Army knife
- Chef knife
- Forged knife
- Outdoor knife
- Scissors
- Stainless steel ball