Chapter 1032 Luo Luo's ingenious plan to bring peace to the world
If the reason for all this is really a problem with the cooling rate, then for Chang Haonan's processing task, all he needs to do is increase the liquid preheating temperature and reduce the cooling rate.
Of course, this is just a principle.
In specific implementation, considering that the neutral salt solution originally used has a high thermal conductivity, and if the preheating temperature is high there will be problems of evaporation or even boiling, there are still some areas that need to be overcome.
Adding another set of pressurization equipment for this purpose will further increase the complexity of the system.
But if I change the type of liquid, it seems that I can’t think of anything that particularly meets the requirements.
The material forming is more complicated.
For conventional metallurgical processes, a dedicated stress relief annealing process can be set up.
However, as a powder forming process, laser selective melting actually cools while processing.
In other words, even for a 10mm cubic specimen, cracks have already formed before the entire forming process is completed.
Therefore, it is definitely too late to anneal afterwards.
Only real-time post-processing can be considered.
That is, annealing is performed while processing.
Fortunately, annealing is essentially a process of slow heating and then slow cooling.
In theory, this could be accomplished with an annealing laser following the processing laser.
If we want to think of other solutions, it will be the metallographic issue.
According to the previous material characterization and the results of calculations conducted by Chang Haonan, the eutectic reaction a→γ+β is very sensitive to the cooling rate. Therefore, a large number of a2 phases with a close-packed hexagonal lattice structure will be formed inside the matrix. This structure has fewer slip systems and is a typical brittle phase. Therefore, the tensile strength of the area containing more a2 phase is lower. When the residual stress is large, it is more likely to become the initiation and expansion area of cracks.
In other words, by reducing the proportion of a2 brittle phase, the occurrence of cracks can be suppressed.
However, the process of melting and forming itself will affect the phase composition of the final product, so one move will affect the whole body, and it is not much simpler than the idea of annealing while processing...
In short, there is no way to solve the problem by just doing something casually.
But at least the research direction can be determined.
After sorting out his thoughts in his mind, Chang Haonan quickly tidied up his desk and then briefly explained his ideas to the other two.
Then, there was a long silence...
Finally, it was Lu Qingsong who spoke first:
"Although there is little evidence...but at least the speculation is reasonable."
Hang Zhibin then said:
"We can specially prepare a batch of samples with different molding progress ranging from 20% to 90%, and then take them for scanning electron microscopy and X-ray diffraction analysis. This can quickly determine whether Mr. Chang's two intermediate speculations, that is, cracks are generated simultaneously during the molding process, and that the content of a2 brittle phase affects the difficulty of crack generation, are correct."
"If both of these are correct, then although it is not particularly rigorous, it can be basically assumed that the crack generation mechanism mentioned by Mr. Chang is correct."
If the mechanism is fine, then there will be no problem with the subsequent solution.
Therefore, the three of them quickly reached a consensus on the matter.
"Then the next step..."
Just as Chang Haonan was about to formally arrange the follow-up work, Hang Zhibin suddenly changed the subject:
"Wait, there's one more thing..."
Chang Haonan and Lu Qingsong turned to him at the same time.
"This process requires multiple comparisons with the samples provided by the British side, and we were also going to conduct comparative tests on the mechanical processing properties of the materials later..."
Hang Zhibin explained:
"So, we need more samples, I mean...semi-finished samples provided by the British side."
Hearing this request, Lu Qingsong was a little hesitant.
"But the number is not enough now..."
However, Chang Haonan agreed readily:
"That's okay. We can just ask Luo Luo for a second batch of samples."
"what?"
Lu Qingsong looked at Chang Haonan in confusion.
The latter replied indifferently:
"The contract does not specify the specific use of these samples, but only requires us to return them after testing."
"We don't want to use it because we're worried about leaks, but Researcher Hang's test is to reverse engineer them, and there are no secrets to leak..."
The confusion on Lu Qingsong's face suddenly turned into enlightenment——
I am still trapped by the fixed mindset...
……
Soon, Rolls-Royce received a request to provide a second batch of processed samples.
In addition, according to the contract, the first batch of consumed samples were also returned to Xiro Company at the same time.
The latter brought it to the UK as quickly as possible in the form of human courier.
The low-pressure turbine assembly is relatively small, and the number of samples themselves is limited, so there is no need to bring a cargo box like last time.
The person in charge of this human courier was Adam Whittle, one of the two British representatives of Silo Company.
As soon as he got off the plane, he was taken directly to the Rolls-Royce headquarters in Derbyshire.
Almost one-third of the Trent 900 project team's executives, including Lapworth, Bodie, and process group leader Nate McGill, were already waiting here.
This posture surprised and delighted Whittle, who had been away from Rolls-Royce's core circle for many years.
"Is this the waste product produced during the Huaxia people's process testing?"
Lapworth carefully pulled out a leaf mold from the sample bag, frowned, and asked.
Although she was addressing Whittle, he was clearly not high on her priority list for answering questions.
McGill, who was sitting next to him, leaned over to take a look and gave a direct affirmative answer:
"Yes, we made special marks on the root and tip of the blade before shipping. This one has obviously not been swapped."
"no……"
Lapworth held his forehead helplessly:
"I mean... the nickel-based alloy blades they brought out last time were perfect, but how come this..."
As she spoke, she turned the blade around and showed it to the other people around her.
Then, there was a collective gasp in the conference room.
The entire upper surface is almost covered with tiny cracks visible to the naked eye.
Without even using any testing equipment, you can tell it's absolute waste.
It is completely different from the samples used in the previous trial production process.
"I would say this is normal."
McGill is responsible for process development and has a clear understanding of the difficulty of this process:
"The processing characteristics of titanium alloys and nickel alloys are very different. They obviously had no experience in this area in the past, so they can only explore from scratch..."
At this point, he took the leaf in his hand, looked at it for a while, and then smiled:
"Moreover, only in this way can we fully understand the Chinese people's research and development process, and thus deduce the specific process routes they used, and even... the process parameters."
Bodi, who had been silent just now, frowned:
"Don't rely on these too much, McGill."
"You know, the results obtained by reverse analysis like this may not always be completely correct...it may even interfere with the normal research and development process."
In fact, he was not very supportive of reverse engineering at first, but McGill persuaded the head of the Trent 900 project, who was also their direct superior, to turn his suggestion into a decision.
After hearing this, the latter returned the blade in his hand to Lapworth, wiped the unknown liquid off his hand and said:
"So... I divided my people into two groups. One group will be responsible for cooperating with Oxford Optical Instruments to continue forward development, and the other group will work with me to try to find something useful from the Chinese test samples."
"And judging from the current situation, the Chinese...are not aware of our methods..."
