If the set collarend hardness is lower than HRC40, should first on the end surface again a built-up welding hard alloy, after the polish repackaging.
如果固定环端面硬度低于HRC40，则应先在端面上重新堆焊一层硬质合金，经磨光后再装配。
2
"If I wore a white shirt to school, by the end of the day it would be brown, " recalls He, who was born in 1974, "and there would be a ring of black soot under the collar."
他回忆说：“如果我穿一件白衬衫去上学，一天下来衬衫就变成了棕褐色。 领子下面还有一圈黑黑的烟灰。”
3
But they're hard to miss in foundering blue-collar and low-end service communities across the country.