Ai was appointed leader of the team, which consisted of 11 workers. He worked on technical breakthroughs by night as he still had work to complete during the day.

The extremely high temperatures posed a different problem.

When welding, copper must first be heated to over 700 C, and after an hour or two of experimenting, Ai would be soaked in sweat.

Undeterred by countless failures, he finally managed to make a successful weld on March 23, 1984, placing second in the National Prize for Progress in Science and Technology the following year.

Ai didn't enjoy the acclaim and turned down the well-paid posts he was later offered by other companies, deciding to stay at the factory and keep improving his skills.

He even started to learn how to use the computer and computer-aided design when he was 58.

In 2015, with the steel industry in a tight spot, Xiangtan was having difficulty. Ai, then 65 and ready to retire, agreed to stay and help the company out of its predicament.

"I had to stay when the company was having trouble. It made me who I am, and it was time for me to pay it back," he said in an interview with the Xiangtan Broadcast Station in late June.

Over the past 50 years, Ai said he has worked to a higher standard because he is a CPC member, not just a craftsman.

He said that a craftsman focuses more on improving skills, while a Party member also has the duty to serve as a role model for peers to follow.