*BK1系列材質為優質氮化鋼38CrMoAl、SACM645*氮化保溫：505℃38小時、550℃34小時*氮化層深：單邊0.48mm以上*氮化層硬度：HV960 以上*直線度每米小于0.06*料管生產范圍：內孔（?14-?250）長度5000mmBK1 series(nitride barrel)*BK1 series is made of high quality nitride steel 38CrMoAl、SACM645*nitride insulation:38 hours of 505℃,34 hours of 550℃*nitride layer deep:unilateral more than 0.48 mm*the hardness:HV960 above*straighthess is less than 0.06 per meter*feed barrel production within the scope of hole (?14-?250)length is 5000mm