The firearm industry relies on tooling and precipitation hardening to deliver steel with enhanced properties such as hardness, strength, and resistance to high temperatures. Shifting barrels and other malfunctions are unacceptable, so heat treatment is a necessity to provide accurate and long-lasting firearm parts. Here, we will discuss how tooling and precipitation hardening work and the advantages it provides to the firearm industry.
What Is Tool Steel?
Tool steel is a carbon alloy steel that is preferable for tool manufacturing applications. The properties that make it ideal for tool manufacturing include its wear resistance, abrasion resistance, shape retention at high temperatures, and hardness. Manufacturers often heat treat tool steel to increase its hardness. Tool steel typically contains various combinations of tungsten, molybdenum, vanadium, and chromium. It may also contain nickel or cobalt for added temperature resistance.
Tool steel comes in various grades, including:
- Air Hardening. This type of tool steel is all-purpose and very versatile. It has high toughness, wear resistance, and good machinability. It is best known for its minimal distortion under heat treatment due to its increased chromium content.
- D Type. This tool steel contains high carbon and chromium contents. It is known for its air-hardening characteristics and abrasion resistance.
- Oil Hardening. This general-purpose tool steel features good toughness and resistance to abrasion.
- Shock Resisting Type. This grade delivers shock resistance at a range of extreme temperatures. It has lower abrasion resistance, but its low carbon content offers toughness and impact resistance.
What Is Precipitation Hardening?
Precipitation hardening is a treatment that applies heat to various alloys to improve their strength. Heat causes solid impurities or precipitates to form on the steel’s surface, reducing dislocation movement and hardening the steel to increase its durability.
Firearm manufacturers can observe the following benefits from precipitation hardening:
- Improved yield and tensile strength
- Decreased flexibility
- Enhanced machinability
- Increased durability and overall strength
Barrels, pistol safeties, receivers, bolts, and other firearm parts benefit from the improved corrosion and heat resistance that precipitation hardening delivers.
The Precipitation Hardening Process
Precipitation hardening is a three-phase process. Solution treatment is the initial phase, which involves dissolving the precipitates and decreasing segregation in the alloy. As the material soaks, the precise application of heat allows it to reach its solvus temperature and create a uniform solid solution. The goal is to remove precipitates and prepare the material for the quenching phase.
Quenching is the next phase of the precipitation hardening process, which involves rapidly cooling the alloy. Quick cooling allows the material to form a supersaturated solid solution with increased copper elements. The rapidity of quenching does not permit diffusion of nucleation sites or the formation of precipitates on the alloy.
The final step of the process is aging. During this phase, the material is heated again but below its solvus point. Heating to this point causes atoms to only diffuse at a small distance, creating a layer of finely dispersed precipitate that strengthens the alloy by decreasing dislocation movement. Aging forms a lattice structure within the material to significantly improve the material’s strength.
S.M. Engineering and Heat Treating for Tooling and Precipitation Hardening Firearms
Tooling and precipitation hardening deliver various benefits for the firearm industry, such as increased durability, reduced flexibility, and enhanced strength. These properties are crucial in ensuing long-lasting and accurate firearm products.
At S.M. Engineering & Heat Treating, we have over 60 years of experience serving various industries with heat treating solutions. We are ISO 9001 certified and provide a wide range of furnace and oven heat treating services. For more information about our tooling and precipitation hardening capabilities, contact us or request a quote today.