Chapter 1031 Laser Selective Melting

"Concentrate on conquering the material itself first?"

After hearing Chang Haonan's idea, Lu Qingsong's first reaction was disbelief:

"From a research perspective, this is indeed more reasonable, but Mr. Chang, won't it be too late in terms of time..."

Compared with developing a new material from scratch... the workload of processing based on the existing materials is always much smaller.

Including the reverse engineering of 4722 alloy according to the original plan, which is also a relatively long task.

Any sudden adjustment of the plan now will have a significant impact on the entire project.

But right now, Chang Haonan really has no choice.

"no way."

He replied somewhat helplessly:

"It is indeed a bit tight in terms of time, but since the attempt to use other titanium alloy substrates for testing and then present the results has been proven to be unfeasible, if we want to obtain the process parameters in a short time, we can only directly take enough 4722 alloy and establish a database and fitting formula for this series of materials alone. This way, the results will definitely be guaranteed to be accurate."

"Now if we want to get enough 4722 alloy, the easiest way is to ask Rolls-Royce for it according to the contract. But I don't want to return all the processing waste to them, because that would leak out too much... So, we can only make preparations for both situations."

"On the one hand, we will focus most of our efforts on the 4722 alloy material itself. Although we probably won't be able to make blades exactly the same as Rolls-Royce's in a short period of time, it would be best if we could come up with a substrate that meets the requirements. In this way, we can use our own materials to complete the computational modeling process without any risk of leakage..."

"Of course, on the other hand, the turbine processing task of the Trent 900 is definitely the most important, so we can't put all our hopes on it. If the alloy forming process still doesn't improve by the end of this year, we can only choose to ask the British for a second batch of follow-up samples..."

After hearing this explanation, Lu Qingsong nodded solemnly.

The same principle applies to technological blockades.

The main purpose is to increase the cost and time for others to catch up.

As long as the speed of technological iteration of latecomers is not as fast as mine, the entire market will still be in a monopoly state.

So, if possible, everyone wants to prolong this process as much as possible.

After a slight hesitation, he continued:

"Then if Xiluo Company wants to know the progress... you know, they are the client after all, we can't not reveal any information to them..."

Chang Haonan answered without hesitation:

"Just say that we are adjusting the process parameters... In addition, the several groups of scrapped products produced in this round of testing can also be disassembled and handed over to them in several batches. It should be enough to handle two or three months..."

"..."

Just when the two were ready to deal with the worst case scenario.

A figure appeared at the door of the office just in time...

It’s Hang Zhibin.

"Boss Chang, and Engineer Lu."

He walked in slowly, holding a folder that was almost identical to the one in front of Chang Haonan.

"We have trial-produced a batch of Ti-47Al-2Cr-2Nb based on the process deduced from the data."

This sentence really shocked Chang Haonan and Lu Qingsong who were just discussing this matter.

Especially the former.

Almost jumped out of the chair:

"Trial production is out? Rods or profiles?"

It’s really no wonder that Chang Haonan was so startled.

The main reason is that it has been less than 20 days since the research started.

In such a short period of time, it would be a bit difficult to develop a complete set of processes even based on existing experience.

Not to mention the output materials themselves.

Even with the help of the system, it wouldn't be so fast...

Looking at the two people with shocked faces, Hang Zhibin also showed a confused expression for a moment.

Then I realized that the other party had misunderstood.

Quickly shook his head:

"How can there be profiles and bars? We just used the atomization process we developed in the past to make a batch of metal powder..."

After hearing his explanation, Chang Haonan breathed a sigh of relief. While he was glad that scientific principles still existed, he couldn't help feeling a little regretful.

Of course, even if it is powder, 20 days is a very good progress.

Therefore, he certainly cannot show his regret:

"It's okay. I've read the information provided by Rolls-Royce. The blade blanks are produced using laser selective melting technology."

"With metal powder, we at least have a foundation for further research on the molding process... In addition, Engineer Lu and I are also considering adjusting our R&D plan. Together with you, we will focus on tackling the production technology of the substrate."

This laser selective melting molding process is a type of 3D printing.

It is not a new technology and has been used in small quantities since the late 90s.

However, at the beginning of the 21st century, it was not possible to directly beat finished products from powder as it was later done.

First, a rough blank is made, and then the traditional processing method is used for subsequent precision processing.

Although Hang Zhibin doesn't know what exactly happened at this moment, for him, having these two big guys joining is definitely not a bad thing.

So he nodded happily.

Then, he excitedly reported another progress:

"In fact, after the powder was produced, we also conducted two rounds of powder spreading and molding tests...but the results were not very good, so they were not included in this report."

"But since you, Mr. Chang, are going to be in charge of this area personally..."

Hearing this, Chang Haonan's eyes lit up again.

Without even waiting for the other party to finish speaking, he hurriedly said:

"Tell me more specifically!"

"Well...it's a trial production, so we made 10mm cubic specimens. However, only the upper and lower surfaces of the specimens are relatively flat. The side walls, especially the side edges, show obvious warping, burrs, and unfused defects. And from these defects, we can also..."

Since he didn't bring the sample testing report, Hang Zhibin could only organize his words while describing the situation, so he was inevitably a little stuck.

However, what he said was quite familiar to Chang Haonan.

So much so that he interrupted the other party midway:

"Are you trying to say that, with the defects at these side edges as the source, many macroscopic cracks have been generated, the kind that can be clearly observed with the naked eye?"

Hang Zhibin nodded immediately:

"right……"

Then I realized something immediately:

"Wait...Mr. Chang, how did you know that?"

"Ugh……"

Chang Haonan sighed:

“Because I have encountered almost the same problem.”

As he spoke, he handed the test report that Lu Qingsong had just brought to Hang Zhibin:

"Take a look. There's a picture on it. Is it the same as you..."

Chang Haonan's voice stopped abruptly halfway through.

Because at this moment, a thought flashed through his mind, sparking a series of sparks of inspiration.

Laser selective melting molding is a process that makes full use of the thermal effect of lasers.

The ultra-short laser processing here is to minimize the thermal effect.

But now the same problem has arisen on both sides...

As we all know, the direct cause of cracks is basically because the residual stress is greater than the tensile strength of the material itself.

However, current picosecond lasers are not actually sufficient to avoid all thermal effects.

In order to solve this problem, when Chang Haonan developed the ultra-short laser processing equipment, he immersed the workpiece to be processed in liquid.

If we have to say what is similar between the molding and processing processes, it is probably only this process.

It's not that the cooling method is the same -

Of course it is not possible to fill the powder with liquid during the molding process.

However, the higher temperature difference makes its heat transfer efficiency close to that of liquid cooling.

That is, the cooling rate is close to

In other words, the stresses themselves are likely to be generated during the cooling of the material.

In addition, the boundary between the unmelted powder and the molten powder will form a gap, increasing the surface freedom, so cracks are more likely to occur on the side of the sample. In contrast, since the upper surface is composed of the last melted molten pool, the surface quality is better and it is not easy to become a crack source.

This can explain why the upper surface of Hang Zhibin's cubic specimen is relatively smooth, while the side edges are in the worst condition.

"Researcher Hang..."

After a long time, Chang Haonan slowly said:

"I think... I've come up with a solution."