High density tungsten alloy has excellent mechanical property, anti burning property and absorption ability to radiation. Therefore, it is used in explosive parts such as armor piercing bomb. Normally, the part should keep well after impacted by the front end explosion, but in the test, the component breaks without external force.
In order to make analysis of the failed component’s fracture failure, the fractured explosive component and different batch of standard components meeting the requirements are compared and analyzed to confirm the failure reason of the explosive component, after makes chemical element analysis, mechanical property test, fracture macro morphology analysis and fracture micro morphology analysis on failed component and standard component , the conclusions can be drawn as follow:
1.0 Through the macroscopic morphology analysis of the fracture, the mode of the failed component is brittle fracture under external impact. The explosive part has been made non-destructively test before it is put into service, and no obvious crack or hole is found in the inside. Therefore, it can determine that the internal factor of the component is the main reason to lead to failure and fracture, and the explosion impact is the inducing factor for the component failure.
2.0 Analyzing the chemical element of the failed part, it shows that the chemical component of the failed part is normal, the microstructure is abnormal and the mechanical property is unqualified. Through metallographic structure and micro morphology analysis, it can be found that there is obvious difference between the internal structure and standard part of the failure part, after investigation it shows that the average temperature zone of the vacuum annealing furnace does not meet the requirement, which leads to the heat treatment temperature of the explosive parts not met the requirement of the technology parameter, so the performance of the explosive part has problem.
3.0 Technology parameters such as heat treatment temperature and holding time should be strictly controlled to limit the use range of the uniform temperature zone of the vacuum annealing furnace, further improve the product qualification test plan for explosive part, give advice and make reasonable plan of the number and location of the test rods along with the furnace.
