HIP – densification of AM components

Additively manufactured components contain a certain degree of porosity which in part is affected by the process parameters used during printing. The pores in the component can act as sites for crack propagation which in turn leads to worsened mechanical properties. By using HIP, the pores can be closed which is key to achieving the desired mechanical properties of a printed component.

Combination of pressure and heat

Quintus Technologies AB is a Västerås-based company which is a world-leader in the manufacturing of HIP equipment. The press equipment installed in the Application Center for Additive Manufacturing is a QIH15L URC^® / URQ^®. The name refers to the size of the press but also indicates that we are equipped with two sets of ovens: one URC and one URQ (Uniform Rapid Cooling / Quenching).

The ovens are made from molybdenum and can achieve a maximum temperature of 1400 °C and a pressure of 207 MPa. The two ovens allow us to both cool in a controlled manner but also use rapid cooling. The pressure medium in the press is argon gas.

The materials that can be used in the HIP are metals and ceramics where the maximum temperature of the molybdenum furnace decides the compatibility with the material. The press can also be used for cast components or for PM. The dimensions of the component are limited by the size of the oven:

URC – 500 mm in height, 165 mm in diameter, 60 kg.
URQ – 250 mm in height, 155 mm in diameter, 40 kg.

Several processing steps in the same machine

The four main parameters that can be varied in the design of a HIP-cycle is pressure, temperature, hold time and cooling rate. A typical HIP-cycle may be to heat at 1200 °C with a pressure of 150 MPa for a duration of 2 hours followed by rapid cooling. The result of such a treatment for example may be full densification but too much grain growth. In that case the cycle can be varied to feature a slightly lower temperature but using a higher pressure instead.

In addition to a traditional HIP-treatment where densification is the main purpose it also possibly for us, using the rapid cooling functionality, to design a heat treatment cycle in the HIP. This can either be done under high pressure, a so-called High Pressure Heat Treatment (HPHT), or alternatively at a lower pressure which could be more similar to a conventional heat treatment. The great benefit of being able to perform a heat treatment in the HIP is that the number of process steps and the total processing time for a given component can be made shorter.

Are you interested in knowing more about how the HIP works or want to discuss the opportunities for your particular component or material? Please contact us for more information!