Table 1 High-strength bolt materials for wind power,domestic and foreign brands,performance specifications,standard number,remarks,EU grades,Japanese grades,US grades,S-class Chinese grades(borrowed),Chinese grades,high-strength
Bolts,high-strength bolts in wind power equipment,mostly medium-carbon alloy steel,not only It is required to have high strength while still having sufficient toughness and plasticity.
Practice has proved that the bolt can have high strength,sufficient toughness and good fatigue resistance after quenching and tempering heat treatment.If the martensite is not fully quenched during quenching to obtain some non-martensitic structure,the strength,toughness and fatigue properties of the bolt will be reduced,especially when the ferrite is distributed along the grain boundary.The degree is even more serious.For this reason,for high-strength bolt quenching and quenching,it is required to obtain martensite over 90%of the entire section.
The main alloying elements contained in the medium carbon alloy steel are C',Ni,M+,M,and the like.Their main role is to increase the hardenability of medium carbon alloy steel,to ensure the martensite is obtained by quenching,and to have sufficient tempering stability when tempering at high temperature,and the tempered sorbite structure is strengthened after tempering.In fact,most of these elements are soluble in ferrite,which strengthens the ferrite.The content of such elements in the medium carbon alloy steel ensures that the ferrite is strengthened without significantly reducing its toughness,and even some can simultaneously improve its impact toughness.
