A cruise ship that has just been completed and left the factory is as strong as a rock. But what people didn't expect was that its hull suddenly broke from the inside in an instant, and it broke into two parts!
This seemingly absurd picture is not a special effects scene in a movie, but a scene that once took place in a shipyard in the United States. So, what is the ins and outs of this matter, and who is the "culprit" who caused the metal hull to become as fragile as tofu?
On January 16, 1943, a giant cruise ship that had just been completed stood proudly in the building of a large shipyard in Oregon, USA, waiting to be delivered to customers the next day before it was officially launched. However, in the middle of the night, the hull of the cruise ship suddenly made an earth-shattering loud noise, waking people up from their sleep.
The panicked workers followed the sound around the steamer, and they were stunned by the sight of the mighty and indestructible ship that had broken in the middle and broken in two. It's a nightmare that makes it impossible to believe your eyes.
The owner of the shipyard was the first to come to his senses, and he gasped, feeling both sad for the great loss of the cruise ship, and at the same time extremely glad that the ship had not yet been put into operation. Otherwise, if the cruise ship were to crack in the middle of the sea with a full load ......of passengers, the terrible consequences would be unimaginable
In order to investigate the truth of the matter, the United States organized a team of experts to go to the shipyard non-stop and conducted a thorough investigation.
The final investigation revealed that the ship's fracture was due to the widespread use of electric welding instead of the riveting process during production, and the high-temperature reaction during welding produced a large number of hydrogen atoms.
The excess hydrogen atoms are like pervasive ghosts, infiltrating every corner of the metal matrix, causing massive damage to its otherwise solid structure. At the same time, hydrogen atoms also cause the metal to flatulate, become brittle, and can break or suddenly brittle at any time.
In this case, even if the cruise ship was not launched and was not subjected to external forces, it was still very easy to break, so there was a terrible scene at the beginning of the article. In the scientific community, this bizarre phenomenon is known as "hydrogen embrittlement".
In addition to the shipbuilding industry, other manufacturing industries that use a lot of metal welding will be threatened and challenged by the "hydrogen embrittlement" phenomenon. And judging from the current level of science and technology, once the phenomenon of "hydrogen embrittlement" occurs, it is like a hidden disease left in the steel body, which is difficult to complete. Therefore, we must take the precautions ahead and increase investment in the detection of "hydrogen embrittlement".
At present, what are the scientific methods that can effectively detect the phenomenon of "hydrogen embrittlement"?
There are three main methods of "hydrogen embrittlement" detection that are most commonly used. The first method is to detect the metal fixtures by applying continuous stress, which professionals call the preload test parallel support surface method.
This method is mainly to put the metal fixture to be inspected into a special test fixture and subjected to continuous pressure for at least 48 hours. In this process, the hydrogen atoms inside the metal material are diffused by the force.
The operator needs to tighten the metal fastener again to the initial state every once in a while. At the same time, check and record whether the phenomenon of "hydrogen embrittlement" has occurred after the diffusion of hydrogen atoms.
This detection method has two obvious advantages, one is relatively low cost, and the other is simple operation. However, this method is also susceptible to many factors such as the material of the sample, the surface temperature, and the time to completion of the sample, which may lead to deviations in sensitivity and accuracy.
The second method is the silicone oil detection method, in which the operator soaks the metal sample to be tested in high-temperature silicone oil for more than five minutes and then observes the surface of the sample.
If there are continuous bubbles on the surface of the sample, hydrogen embrittlement has occurred. The disadvantage of this method is that the temperature of the silicone oil is too high, which can sometimes damage the metal sample.
The last method is acoustic emission detection. Acoustic emission technology is widely used in the detection of damage to the internal structure of metals, so it can also be applied to the detection of "hydrogen embrittlement".
Compared with the above two methods, the acoustic emission detection method can achieve non-destructive testing of metal samples, and the accuracy and rigor are also higher. However, this method has a high cost and certain professional requirements, so it has not yet been fully popularized.
Major engineering enterprises can choose the appropriate detection method according to their own situation. At the same time, in order to better prevent the occurrence of hydrogen embrittlement, there are many things to pay attention to in the production process.
For example, in the production process, the metal material should be fully dried to remove the moisture and impurities in it, so as to avoid the hydrogen atom being stimulated to reactIt is also possible to control the welding parameters and welding sequence during the welding process to avoid excessive welding stress and excessive welding temperatureAfter the end of production, we should not relax our vigilance, and should regularly inspect and maintain metal materials and products, and find and deal with abnormal phenomena in time.
In short, although "hydrogen embrittlement" is very terrible, with the continuous attempts of workers and the continuous development of scientific methods, the harm it causes to human beings is also decreasing. We also sincerely hope that there will be a more perfect solution in the near future, and completely put an end to the disasters and tragedies caused by "hydrogen embrittlement".