For nearly seven years, Li Wei rose before dawn for his 10-hour shift at the steel plant, returning home each night soaked in sweat, the clank of heavy machinery still ringing in his ears. But last month, the 31-year-old welder stood outside the plant with hundreds of co-workers, picketing against pay cuts and singing patriotic battle hymns. Within a week, the authorities declared their strike illegal, threatening fines and imprisonment. The police descended on the plant by the hundreds, tearing down signs and ordering the protesters to go back to work. “I’ve sacrificed my life for this company,” Mr. Li told officers as they sought to disperse the workers. “How can you do this?” As China ’s economy slows after more than two decades of breakneck growth, strikes and labor protests have erupted across the country. Factories, mines and other businesses are withholding wages and benefits, […]