Metal Technology Co. Ltd.





These FAQs were answered during the MTC webinar. Please click here for more details.


What metals are suitable for bonding using the HIP process?

Most metals can be HIPed and some of the common metals we process are copper, aluminum, stainless steel, titanium, and tantalum, etc. Please contact us with your specific needs.

What is the level of precision of the bonded section for the two processes of HIPping and hot press?

The hot press bond is 99% when the component processing accuracy and conditions are met and 100% when the HIP conditions are met.

What is the required surface roughness for the bonding surface?

It is approximately Ra6.3.

What is the bonding strength at the bonding interface?

It depends on the combination of joining materials. For example, the combination of SUS304 and C1020 has higher joint surface strength than the base material of C1020.

Are there any alloys that are difficult to bond with the HIP process?

There are some challenging materials when using the HIP process, however HIP is excellent at bonding dissimilar materials.

Are special finishes required for bonding surface processing?

No, basically, there is no problem with normal metal processing.

What is the percentage drop in bonding strength in homogeneous metals compared to the base metal strength?

It depends on the bonding conditions. In the best case of bonding, the strength of the bond is equal to that of the base metal.

Is there a way to distinguish which dissimilar metals are easy to bond?

Combinations that have large solid solution limits to each other in the two-dimensional state diagram are easy to diffusion bond.

Is there a way to distinguish which dissimilar metals are difficult to bond?

Metals with very different expansion coefficients and melting points do not match well.

If I want to increase the bonding strength of dissimilar metals, which has a greater impact, temperature or pressure?

Temperature has a greater impact.

In bonding dissimilar materials, do intermetallic compounds form as in welding?

Some types of metal components tend to form intermetallic compounds. If a large number of intermetallic compounds are formed, they will break off from there, so it is necessary to create a combination that prevents the formation of intermetallic compounds. MTC has both the experience and know-how to resolve this issue if required.

Doesn't the capsule material bond to the product when HIPping?

Yes, the capsule does bond to the product but this is removed after HIPping or Heat Treatment through pickling or machining. MTC has extensive experience with capsule removal and techniques to ensure the products integrity.

What is the result of the bonding process at the interface?

Since the atoms at the bonding interface are diffusion bonded together, the layer is very thin, about 1 micron.

Are capsules made for each product?

Yes, in rare cases two components are placed in one capsule, but basically they are made product by product.

Are capsules used for HIP reusable?

Each capsule is only used once.

What is the standard capsule material?

Metals with good weldability, such as iron-based and stainless steel-based metals, are generally used.

Is a capsule also necessary in the case of HIP for the purpose of removing internal defects?

Defects that are not externally exposed (meaning internal defects) do not require canning (encapsulation). HIP is possible with the bulk material as it is.

Does MTC have experience with diffusion bonding CoCr and a titanium alloy?

Here at MTC we have processed several combinations of materials including pure titanium and pure copper. Please contact us for a specific combination of materials.

I want to bond aluminum and copper together by methods other than brazing.

MTC can offer alternative options to match your needs and requirements through diffusion bonding processes. As each case is specific and MTC matches the process to the customers needs we suggest that you contact us with the details and we can provide you with a customer specific suggestion.

Is it possible to join metal and ceramics?

Depending on the shape of the bonded part, brazing is recommended if it is metal and ceramics; MTC normally braze's metal and alumina. There is no established technique for bonding metals and ceramics by HIP.

Is it possible to bond (braze) alumina, metal or brittle materials to each other?

Depending on the shape of the bonded part, it is possible to bond alumina and metal by brazing. Bonding of brittle materials is also possible if sufficient diffusion occurs. However, due to the effect of different expansion coefficients between the capsule material and the product, the capsule often cracks after HIP.

Why is it difficult to bond ceramics to ceramics?

Canning (encapsulation) is also required when ceramics are bonded together by HIP. This is because it is difficult to produce a capsule that can withstand the temperature at which ceramics diffuse.

SUS and Ti cannot be bonded by welding, but can they be bonded by HIP?

It is possible to bond by HIP. However, there are various conditions for titanium. Please contact us for details.

Is it possible to make mille-feuille shaped products?

If canning (encapsulation) is possible, it is possible.

Are there any methods of diffusion bonding thin sheets with HIP? (e.g. several mm in thickness and 300φ in diameter)

Hot press is more suitable for diffusion bonding of thin plate products than HIP. It is also less expensive. Hot pressing is also available at MTC, so please contact us.

Is the aluminum 7000 series not suitable for HIP bonding?

HIP bonding slowly cools strong metals, resulting in annealing.

At the time of diffusion bonding of SUS304, if the surface phase of the part is Ra6 or less, it will be a mirror surface. A carbon pressure jig is recommended, but can the two react?

SUS304 and carbon jig may react a little and fuse. Basically, it is better to include the finishing process after bonding.

Are there no internal stresses after HIP?

Internal stress is generated. However, since the cooling rate of the bonded interface is slow, the stress is generally released.

How do you pressurize the HIP unit?

There is a high-pressure compressor on the outside of the unit which pressurizes the HIP during processing.

Is there any possibility of metal recrystallization during the HIP process?

HIP at a temperature higher than the recrystallization temperature will cause recrystallization. Whether recrystallization should occur depends on the mechanical properties (strength/viscosity) the product is intended for, so please contact us for details.

What happens if you create a space inside and HIP it?

As long as it is open to the atmosphere, no deformation will occur. Any openings or porosity that is not exposed to the atmosphere, will be eliminated. If the space is internal it will be closed by the HIP process.


How does the hot press process compare to HIP for cost?

Since HIP requires additional processes, such as capsule design, construction, and evacuation inside the capsule, processing products with HIP tends to be more expensive than the Hot Press process. However, there are several advantages to both processes depending on the result desired by the customer. comment - Link to HIP -

How can I decided what the best process is to match my cost and bond surface requirements?

Here at MTC we have vast experience in using both processes and a wide selection of equipment which we can propose to achieve the best and most suitable bonding method in terms of cost for the required quality.


How many hot press units does MTC have?

MTC has nine Hot Press units with a variety of working zones and pressures.

What is the maximum size diameter that can be handled for pressure sintering of metal powders?

The Giga-HIP (equipment name) at Himeji Plant can be used up to about φ1900.


What kind of methods are available for evaluation and inspection of bonded surfaces for diffusion bonding and HIP treatment?

We perform leak inspections (Helium leak test) and tensile tests.

When you manufacture mass produced parts how do you ensure the quality?

Here at MTC we have and utilize constant process control and quality assurance guaranteeing the process is performed correctly and accurately every time.

Is the temperature during heat treatment controlled by a heat pattern?

Temperature is controlled by attaching thermocouples inside the furnace. If requested, we can also attach thermocouples to the actual product for entity temperature control.

Is the success or failure of the HIP process only confirmed by cross-sectional observation?

This can be confirmed by X-ray inspection and ultrasonic testing.

How do you control the purity of Ar?

We regularly measure the purity of the Ar gas we use.

Compact electron beam irradiation device

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Any request about products, and ask for quotation can be made here. Other questions and requests about the company can also be made here.

Document download

  • Company information
  • Technology information (Japanese)
  • Technology information (English)
  • HIP unit list
  • Hot press equipment list
  • Possible material combinations for brazing
  • MICROTRON Test Machine MIC1
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