Like molybdenum, tungsten is more efficient in high carbon steel than in low carbon steel.Titanium, niobium and zirconium are strong carbide and strong nitride forming elements, whose behavior is similar to vanadium.These elements have little or no solubility in austenite and contribute little to hardenability.Boron is a powerful element in increasing hardenability, and its influence on hardenability is unique and complex.Boron has two states in steel, the solid solution state and the combination state.Only when boron is dissolved in austenite can it play a role in increasing hardenability.Boron with oxygen and nitrogen form boron oxide and nitride, caused quite a number of boron content in combining with the state, and thus lose the ability to increase the hardenability, therefore, should be taken to protect the method of boron and boron and reserved for the combination state and moved to the solid solution, become later after quenching can work on hardenability of the so-called "effective boron.

Effect of alloying elements on tempering transformation of quenched steel: Compared with carbon steel, Q345B alloyed round steel has higher tempering softening resistance, and can show secondary hardening in some cases.The reason why Q345B alloy resistance round steel has the emstabilization martensite decomposition, residual austenite transformation and cementite precipitation and agglomeration are pushed to a higher temperature range in different degrees under the condition of adding alloying elements. Different alloy elements play different roles in slowing down temperature forming nickel softeningide. and weak carbide forming elements manganese have little softening effect on tempering steel, and the carbide forming element is more effective in resisting tempering softening.

Carbide forming elements can keep more carbon in martensite, thus hinder the decomposition of martensite. Among them, strong carbide forming element vanadium action *** is the most significant, tungsten, molybdenum is the second, chromium is the second. also hinder the residual austenite transformation and the agglomeration of the alloy cementite, so that the q345B alloy round steel containing the carbide forming elements can keep the fine cementite particles at higher temperature temperature.The non-carbide forming element silicon plays in a unique ro transition, and silicon does not diffuse at low temperature. The decomposition temperature of martensite can be increased by adding Shifeng. Silicon also impedes agglomeration and growth of cementite particles.

Influence of alloying elements and impurity elements in Q345B round alloy steel on mechanical Properties of Quenched and tempered steel The influence of alloying elements and impurity elements on mechanical properties of steel is closely related to the microstructure state of the steeled. The hardness of Q345B alloy round steel only depends on the carbon content in the martensite and has nothing to do with its alloying elements. However, after tempering, the plasticity and toughness of the steel under a given yield strength are closely related to the composition of the steel.