There are many similarities between the heat treatment of metal explosive composite materials and the heat treatment of single metal materials. For example, the materials are heated to a predetermined high temperature at a certain heating rate, maintained at this temperature for a certain period of time, and then cooled at a certain rate. The whole process is carried out in air, in vacuum or in other media (water, oil). Take annealing as an example, divided into high temperature, medium temperature and low temperature annealing. The purpose is also to recrystallize or relieve stress. According to different material, organization, state and performance requirements, heat treatment under different processes.
The heat treatment of explosive composite materials also has its special features, that is, the two or more components that make up the composite materials must first be considered, their respective melting points and recrystallization temperatures, strength and plasticity, corrosion resistance and wear resistance, and ratios. Physical and chemical properties such as thermal and thermal expansion coefficients, especially their interaction characteristics at high temperatures. So as to correctly design the process parameters of heat treatment and predict the influence of heat treatment on their bonding zone structure, bonding strength and respective matrix structure and performance.
The heat treatment of explosive composite materials and the formulation of process parameters must correctly handle the above-mentioned many contradictions, and achieve the unity of process, organization and performance in the vastly different metal combinations, so as to provide reliable organization and performance for the normal use of explosive composite materials. Guarantee.
4.2 Annealing of explosive composite materials
Annealing is an important process that is frequently used in the subsequent processing of explosive composite materials. Annealing of this type of material has three purposes:
First, eliminate the residual stresses of different directions and magnitudes formed on the surface, interface, bottom surface and interior of the composite material during the explosive welding process, including the residual stress in the welds of the equipment and components made of explosive composite materials. This annealing temperature is the lowest.
Second, eliminate explosive hardening and explosive strengthening, creating conditions for subsequent mechanical processing of composite materials. For metal materials with higher original hardness and strength, their explosive hardening and explosive strengthening tendencies are stronger. At this time, this annealing is particularly important. Their annealing temperature is higher.
Third, recrystallization annealing. This kind of annealing can maximize the recrystallization of the deformed structure of the bonding zone, the composite layer and the base layer without severely losing the bonding strength of the composite material, thereby creating conditions for their subsequent pressure processing, mechanical processing and use. In the press working process, intermediate annealing is sometimes performed. The final product sometimes has to undergo finish annealing (soft state). This annealing temperature is the highest.
The annealing process of explosive composite materials is formulated according to the above-mentioned different purposes. A lot of practical experience points out that the principle of formulating the annealing process for this type of material is to first consider the melting point of the lowest melting point in the metal combination, and then consider whether the phase diagram based on the main element in the combined metal is a solid solution or contains intermetallic compounds, or Both. Especially important when annealing at high temperature.