Lub raj seamless yog tsim nyob rau hauv ib thooj, ncaj qha pierced los ntawm puag ncig steel, tsis muaj welds rau saum npoo, thiab muaj ntau yam kev siv. Vim tias cov txheej txheem tshwj xeeb ntawm seamless steel raj, carbon structural steel, tsis tshua muaj hlau alloy steel, thiab lwm yam. feem ntau yog siv rau ntau lawm, ...
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