All of our 12.9 grade of track bolt,plow bolt,segment bolt and nut made in 40Cr or 42CrMo,black finished,hardness are HRC38-42. We are professional manufacture of earthmoving fastener,all of our fastener are made by high grade alloy steel,the surface hardness can reach HRC36-42,tensile strength is 170,000 P.S.I. There are 10.9,12.9 class of track bolt and nut,plow bolt and nut,segment bolt with ...