In the fields of mechanical machining and the manufacturing of wear-resistant parts, Cemented Carbide (often referred to as Tungsten Carbide) is the material of choice due to its high hardness, exceptional wear resistance, and rigidity. It is widely used in cutting tools, molds, and mining tools.
Among the various classifications, the YG Series is the most fundamental and commonly used category. This article breaks down the naming convention, composition, and selection logic of these grades to help you make the right choice.
1. Decoding the "YG" Designation
The designation "YG" is derived from the Pinyin initials of the Chinese terms for Hard (Ying) and Cobalt (Gu).
▶Composition: The basic composition consists of Tungsten Carbide (WC) as the hard phase and Cobalt (Co) as the binder phase (the bonding agent).
▶The Number: The number following "YG" roughly indicates the percentage of Cobalt content. For example, YG8 contains approximately 8% Cobalt.
2. The Logic: Hardness vs. Toughness
Cobalt acts like "glue" in the alloy structure, binding the extremely hard but brittle Tungsten Carbide particles together. The percentage of Cobalt directly determines the performance characteristics of the material:
▶Higher Cobalt Content: Increases toughness and shock resistance, but decreases hardness and wear resistance.
▶Lower Cobalt Content: Increases hardness and brittleness, but reduces toughness (making it more prone to chipping).
3. Common Grades and Their Applications
By adjusting the Cobalt content, manufacturers create specific grades for specific tasks. Here is a breakdown of the most common YG grades:
Low Cobalt: YG3 (~3% Co)
▶Characteristics: Highest hardness in the series, but relatively brittle.
▶Applications: Ideal for finishing cast iron or non-ferrous metals. It performs best in continuous cutting conditions where the machine tool has good rigidity.
Medium Cobalt: YG6 (~6% Co)
▶Characteristics: Strikes a good balance between hardness and toughness.
▶Applications: Commonly used for semi-finishing cast iron, stainless steel, or light-load milling operations.
Medium-High Cobalt: YG8 (~8% Co)
▶Characteristics: Significantly higher toughness than YG3 and YG6.
▶Applications: The preferred choice for roughing, interrupted cutting, or unstable machining conditions. It excels in milling cast iron parts or machining blanks with uneven surfaces.
High Cobalt: YG15 (~15% Co) & YG20 (~20% Co)
▶Characteristics: As Cobalt content rises to 15-20%, the hardness decreases significantly, but impact resistance and fatigue resistance increase drastically.
▶Applications: These grades are rarely used for cutting tools. Instead, they are engineered for non-cutting applications that must withstand heavy shocks or alternating loads, such as:
• Cold heading dies
• Wire drawing dies
• Rock drill bits
• Wear-resistant liners
4. Important Limitations: Don't Use YG on Steel
It is crucial to note that YG series cemented carbides do not contain Titanium or Tantalum.
▶The Risk: Therefore, they are not suitable for machining ordinary carbon steel or alloy steel. When cutting steel at high temperatures, the Tungsten Carbide reacts chemically with Iron (diffusion wear), leading to severe "sticking" and rapid tool failure.
▶The Solution: For machining steel, you should select YT (containing Titanium Carbide) or YW (Universal type) carbide grades.
5. Beyond the Grade: Other Factors
While selecting the right material grade (YG3 to YG20) is essential, optimal performance also depends on other variables. Even the toughest grade, like YG8, can suffer from abnormal wear if subjected to severe vibration or improper feed rates.
Always consider:
• Tool geometry
• Cutting parameters (Speed/Feed)
• Cooling methods
• Machine rigidity
Conclusion
The transition from YG3 to YG20 represents a sliding scale between Hardness and Toughness.
Understanding this basic logic allows manufacturers to lock in the appropriate material grade quickly. Whether your goal is achieving a mirror finish (Low Co) or withstanding heavy-duty impact (High Co), choosing the right grade prevents the inefficiency of "using a sledgehammer to crack a nut" or the waste of using a tool too fragile for the job.
Looking for the perfect Cemented Carbide solution? Contact us today for expert advice on material selection.
