Vacuum Brazing Cr12MoV Tool Steel to Tungsten Steel

A cutting tool may seem simple at first glance. However, it is actually a carefully designed blend of materials, processes, and precision control. The main challenge arises when a tool needs to be very hard at the cutting edge, while also being tough and reliable in its body. No single material can meet both needs perfectly.

This is why the world of high-performance tooling often combines the best of both worlds: the extreme, diamond-like hardness of Tungsten Steel (Carbide) and the high-strength, shock-absorbing toughness of Cr12MoV die steel.

But how do you join two metals with differing thermal expansion properties? Traditional welding often leads to thermal cracking or internal stress. Vacuum brazing has proven to be the most reliable and industrially accepted method for joining two metals that breathe differently when heated, without compromising material properties.

Thermal Expansion Coefficients

Cr12MoV: ≈11-12 * 10^-6/k

WC-Co carbide: ≈5-6*10^-6/k

Chemical composition of Cr12MoV (mass%):

C: 2.0 – 2.3

Cr: 11.0 – 13.0

Mo: 0.4 – 0.6

V: 0.15 – 0.30

Mn, Si: about 0.2 – 0.6 each

Fe: balance

Mechanical Properties after HT: 58 – 62 HRC, very good wear resistance, high hardenability, and dimensional stability

In a vacuum furnace, Cr12MoV can be:

a. Austenitized typically at 1000 - 1040  (depending on section size and requirements)

b. Oilquenched, gasquenched, or interrupted cooled

c. Tempered 2–3 times, usually at 180 - 520  depending on the required hardness

Tungsten Steel, Typical WC-Co grade:

• WC (tungsten carbide): 88-94 %
• Co (binder): 6-12 %
• Hardness: 88-93 HRA (about 1600-1900 HV)
• Very high wear resistance, good hot hardness, relatively brittle

Conventional welding methods generate high local temperatures and steep thermal gradients. When used with Cr12MoV and tungsten steel, these conditions frequently cause residual stress, interface cracking, oxidation, and carbide degradation. Although a joint may appear satisfactory externally, internal defects can substantially decrease tool life during service. Such risks are unacceptable for high-performance and high-value tools.

Vacuum Brazing Process

Vacuum brazing is a joining process in which the base materials remain solid while a brazing filler alloy melts and flows into the joint gap. This process occurs within a high-vacuum furnace, which removes oxygen and contaminants. The controlled environment ensures oxidation-free surfaces and enables the filler metal to form a strong metallurgical bond between Cr12MoV and tungsten steel without damaging either material.

Technical specifications for a perfect joint

Feature                                                        Technical Detail

Base Material                           Cr12MoV (High carbon, high chromium cold-work die steel)

Tip Material                              Tungsten steel/Cemented Carbide (YG8 or YG15)

Vacuum Level                            10^⁻2 and 10^⁻3 pa for optimal purity

Filler Material                           Silver-based or copper-based alloys (depending on tool application)

Bond Integrity                           Zero porosity, high shear strength

A key advantage of vacuum brazing is its ability to provide uniform heating and cooling. Gradual temperature changes minimize thermal stress, which is particularly important when joining materials with different thermal expansion coefficients, such as Cr12MoV steel and cemented carbide. This results in joints with high strength, excellent dimensional accuracy, and long-term stability.

Brazing Filler Materials and Process Temperature

The selection of the brazing filler alloy is critical to joint performance. The filler must effectively wet both materials and maintain strength during service. In industrial applications, nickel-based or nickel-containing brazing alloys are frequently used for Cr12MoV–tungsten steel joints due to their excellent wettability and diffusion bonding behavior. Brazing temperatures typically range from 750°C to 1100°C, depending on the filler alloy and tool design, to ensure reliable alloy flow without altering the base material structure.

Stable vacuum levels, typically between 10^⁻2 and 10^⁻3 pa, are required to prevent oxidation and ensure clean joints. Precise temperature uniformity across the heating chamber allows complex tools to be brazed with consistent quality. Advanced vacuum furnaces, such as those developed by Normantherm, provide the necessary control for repeatable, industrial-scale production.

Industrial Applications

Vacuum-brazed Cr12MoV–tungsten steel tools are widely used in cold stamping, metal cutting, forming, and wear-resistant applications. In these environments, vacuum-brazed joints consistently outperform mechanically assembled tools and conventionally welded components, offering improved reliability and reduced maintenance costs.

Normantherm Vacuum Brazing Furnaces

Normantherm vacuum furnaces are specifically designed to meet the stringent requirements of brazing tool steels and cemented carbides. By combining stable high-vacuum performance, accurate temperature control, and reliable process repeatability, Normantherm systems enable manufacturers to achieve consistent, high-quality brazed joints. Vacuum brazing in a Normantherm vacuum furnace represents an optimal solution for joining Cr12MoV tool steel and tungsten steel in industrial applications.

Edited by: Shristi Paudyal

© 2026 Normantherm Vacuum Furnace. All rights reserved.

Related Products: Vacuum Brazing Furnace (V1300 series)