Fang Guisheng only borrowed a briquette stove from the canteen when he was doing heat treatment before, and did not make another firewood stove like Zhou Jianhua, although he didn't know very well what Zhou Jianhua wanted to do, but he didn't say anything, and said in his heart that when the two section chiefs came, they would naturally know what they wanted, and I would see what kind of fame you could make.

Sure enough, Zhou Jianhua and the three of them waited for less than half an hour, and Director Chen Guodong accompanied Yan Donghai, section chief of the technical department of Changhong Coal Mine, and Wang Shiqing, section chief of the technical department of the Machinery Repair Plant of the Mining Bureau, to the machine repair class workshop. Everyone is an old acquaintance, only Zhou Jianhua, Yan and Wang, the two section chiefs, are meeting for the first time.

Chen Guodong enthusiastically introduced Zhou Jianhua to Yan and Wang, the two section chiefs, and when they said that Zhou Jianhua was still a junior high school student in school, their eyes widened in surprise, Yan Donghai and Wang Shiqing glanced at each other, and both shook their heads slightly with a wry smile.

Director Chen did not introduce Zhou Jianhua's situation on the phone before, but only said that there was a master who had a way to improve the service life of the repair chain and wanted to find J553 welding rod. It just so happened that the mining machinery repair plant was also trying to repair the mining chain at the request of the Changhong Coal Mine recently, but the effect has not been ideal, so as soon as Yan Donghai received a call from Director Chen, he hurriedly asked Wang Shiqing to take the time to come over to investigate.

Yan Donghai and Wang Shiqing were both college students in the early sixties. Today, Yan Donghai is the technical authority of Changhong Coal Mine and even the entire Jiancheng Minerals Bureau in the professional field of coal mining, and Wang Shiqing is a senior engineer in the machine repair factory directly under the Jiancheng Minerals Bureau. With the business experience and experience of the two of them, they can't believe that a small junior high school student can solve the professional technical problem in the field of industrial technology, and now when they see Zhou Jianhua, they are naturally disappointed.

Fortunately, Yan and Wang are both intellectuals who have recuperation, although they are very disappointed, they feel sorry for the precious time of this morning, and they blame Chen Guodong, who does not know how to do it, for treating it as a child's play, but because of the situation, it is not easy to say it in person, so he can only shake his head and smile bitterly, and he also said that he couldn't imagine that Zhou Jianhua would have a unique skill at such a young age, and he would be terrible in his later life.

As soon as Zhou Jianhua saw the changes in the faces of the two section chiefs, he knew that the two of them were insincere, and he didn't mind, so he replied politely with a faint smile:

"The two section chiefs have spoken, I'm just more interested in the technical aspects, and I learned something blindly without anything, but I didn't expect it to be used, and I will ask the two seniors for more advice in the future."

Yan Donghai half-jokingly responded: "Master Xiao Zhou is polite, although there are some new and old technical personnel who have graduated from colleges and technical colleges in Changhong Coal Mine and Mining Machinery Repair Factory, which are full of talents, there are indeed some practical technical problems in production that cannot be solved." No, I heard that you are sure to improve the service life of the repair mining chain, so I asked the section chief Wang of the mining machinery repair factory to come over and learn together! ”

Chen Guodong, who was accompanying him on the side, hurriedly said: "What is Section Chief Yan talking about, if you want to say that learning is also learning from you, you two are here to help guide you." ”

Chen Guodong also saw that the two section chiefs were quite disappointed after seeing Zhou Jianhua, and he was also unsure of Zhou Jianhua's ability in machine repair. Now Chen Guodong is also nervous, so he can only wait for Zhou Jianhua to finish and see the results, so he turned his head and asked Zhou Jianhua:

"Xiao Zhou, how are you preparing, can you start?"

"Hmmm! OK! Zhou Jianhua replied briskly: "Everything is ready, just wait for the east wind of the two section chiefs!" ”

Chen Guodong handed a small package of J553 welding rods brought by Yan Donghai to Zhou Jianhua, Zhou Jianhua took the welding rod and walked out of the workshop, and everyone followed.

Zhou Jianhua looked at the chain link that had been burned orange in the briquette furnace, felt that it was almost there, and the heating time was enough, so he turned on the welding machine, put on protective gloves and goggles, clamped the J553 welding rod on the welding tongs, and then pulled out the chain on the coal stove and put it on the iron plate that had already set up the ground wire, picked up the welding tongs and quickly welded the chain link interface that was replaced, and then knocked out the welding slag and quickly smoothed the weld with a hand mill, and then put the welded chain back into the furnace.

Zhou Jianhua put away the welding tongs, took out the broken ceramic jar that had accumulated a little urine and put it next to the briquette stove, poured in some salt from the canteen in advance, mixed some water into it, and stirred it a few times with the firewood sticks scattered next to it.

Soon, the chain was burned red again, Zhou Jianhua picked up the chain, threw the middle link and several other links connected into the ceramic jar, and a burst of water vapor with a sour smell immediately rushed out of the ceramic jar and filled the air.

Zhou Jianhua didn't stop, picked up the chain from both sides of the ceramic jar, turned around and put it on the simple firewood stove that was burning firewood next to it, so that the chain link to be repaired was still hanging down on the firewood that was burning violently. Zhou Jianhua picked up a few pieces of firewood and threw them into the stove, let them burn slowly, then turned around and smiled at everyone and said: "That's basically fine, let this fire keep burning for an hour, and then leave it in the stove to cool down naturally." ”

During the whole process of Zhou Jianhua's operation, everyone was carefully observing every step of his operation, no one spoke, everyone was watching and thinking intently.

Fang Guisheng, the head of the machine repair team, had been watching every step and action of Zhou Jianhua's electric welding and heat treatment just now, and found that Zhou Jianhua's welding and grinding techniques were completely the work of a skilled technician, and his skills were obviously not worse than his own, and he was secretly surprised, and his heart was unbalanced. At this time, hearing Zhou Jianhua say, "It's okay", Fang Guisheng couldn't help sneering in his heart, and couldn't help but smile at Zhou Jianhua:

"Is that all there is? You only did quenching and tempering, not even annealing, and if you do this, I'm afraid it will break if you don't even use it for two days! ”

Fang Guisheng said that, shook his head disdainfully, and stood aside and looked at Zhou Jianhua gloatingly.

Seeing Fang Guisheng's appearance, Zhou Jianhua pursed his lips and smiled faintly, and explained to everyone:

"The annealing process of 25MnV alloy steel is very demanding in terms of temperature and time control curves, and the slightest deviation in control can lead to severe embrittlement of the material. But with us, including the mining machine repair plant, the existing heat treatment equipment is certainly not up to this level of control. So, for us, the best way to do it is to abandon the annealing process. Although the best effect cannot be achieved without annealing, at least it can ensure that it is not brittle, and the original good toughness of this alloy steel can be maintained above a certain level......"

"What Master Xiao Zhou said is right!" When Wang Shiqing, the section chief of the mining machinery repair factory, heard Zhou Jianhua say this, he looked at Zhou Jianhua again with wide eyes in disbelief, and interjected in surprise: "I and the masters of the mining machinery repair factory have also found the situation you said after testing many times, so we no longer do annealing treatment when we repair this chain later." I really didn't expect that Master Xiao Zhou could think of this for the first time when he did this, and sure enough, there were two hits! ”

"Hehe, that's what the hero sees." Zhou Jianhua nodded to Wang Shiqing and continued to explain:

"Moreover, before quenching, I kept it at a temperature of 750 to 900 degrees, including before and after welding and the surface grinding of the weld is about 800 degrees Celsius, which ensures that the stress of the weld is minimized, and this operation also has a certain annealing effect."

Zhou Jianhua paused, turned his head again, smiled at the other party, Gui Sheng said:

"Master Fang, the two chain links you repaired before were quickly worn and corroded in less than three days, I guess the main reason is because you have carried out annealing treatment, but you have not been able to control the temperature and time of annealing, resulting in brittle materials, so that the repaired chain links are strongly used in use, and the surface quickly produces many fine cracks due to fatigue, so that it is eroded by groundwater rich in chemicals, which eventually leads to its rapid wear."

"Oh...... Is that so...... I thought it was ......," Fang Guisheng muttered in a low voice.

After listening to Zhou Jianhua's explanation and Section Chief Wang's words just now, Fang Guisheng had already understood at this time, it turned out that he was pretending to be smart, so that he appeared in front of everyone, and immediately blushed in shame, shrunk aside and stopped talking.

"But I still don't understand a question, and I want to ask Master Xiao Zhou for advice." Wang Shiqing spoke again.

Zhou Jianhua's operation and explanation just now made Wang Shiqing realize that the young man in front of him was by no means ordinary, so he was also respectful to Zhou Jianhua in terms of words.

Zhou Jianhua hurriedly owed Wang Shiqing, and said modestly: "Section Chief Wang, you are too polite, you don't dare to ask for advice, if you have any problems, you can say it, let's discuss it together." ”

"Hehe, you're welcome, I'm really going to ask you for advice." Wang Shiqing smiled humbly and said: "We all know that the use of high-temperature tempering for quenching and tempering treatment helps to improve the strength and toughness of this material, but you use a wood stove for low-temperature tempering, what is this for?" ”

Wang Shiqing obviously came prepared, and he has a very clear understanding of the conventional heat treatment process of 25MnV alloy steel.

"Section Chief Wang, you have asked this very good question!" Zhou Jianhua nodded to Master Wang with great appreciation and replied:

"As you said, if you use high-temperature tempering treatment, it can indeed improve its strength and toughness. However, 25MnV steel has a very special place, it will produce very obvious tempering brittleness when tempered at high temperature, and the increase in brittleness will also lead to similar results as Master Fang's heat treatment method, the surface of the chain link will produce fine cracks, and eventually lead to premature wear failure. ”

"You have a point! Yes, yes! That's how it should be! The service life of the chain links repaired by our factory cannot be improved, and it is likely that this is the main reason! Wang Shiqing was mentioned by Zhou Jianhua, and immediately realized the crux of the unsuccessful repair of the chain link in the previous mining machine repair plant, and couldn't help but nod his head in admiration.