This standard specifies the internally threaded cylindrical pins with a nominal diameter of d=6 to 50 mm, a tolerance of m6, and materials made of unhardened steel and austenitic stainless steel.
GB/T 120.1-2000 history
2000GB/T 120.1-2000 Parallel pins with internal thread,of unhardened steel and austenitic stainless steel
1986GB/T 120-1986 Parallel pins with internal thread