## 8 The Effect of Alloying Elements on Electrical Steel
### Effect of Manganese  
Manganese (Mn) is a beneficial element in alloys as it effectively increases electrical resistance, leading to reduced losses. It is essential to maintain low sulphur content to avoid the unwanted precipitation of MnS, enabling Mn to remain in a solid solution [85].  
Figure 12: Initial magnetization curves of 0.35 mm thick CoFe and NiFe [81].  
In S-free steel materials, Mn additives ranging from 0.25% to 0.64% by weight result in linearly reduced losses (approximately 2.40 W/Mn wt%) and increased permeability and grain development. Studies have shown that electrical steels with 0.3% to 1.25% wt% Mn in Si-free steels exhibit improved magnetic properties, but higher Mn content leads to smaller grains, which, in turn, led to a deterioration in magnetic losses [86]. In ultra-low S grades with 0.5% wt% Si, the precipitation of MnSiN\({}_{2}\) occurs, causing a decrease in grain size and an increase in [222] tissue components up to 0.94 wt% Mn [87].  
Alloying with manganese has demonstrated textural improvements in alloy steels with high Si content [88]. In high-purity 0.5% wt% Si steel, adding 1.3% wt% Mn results in a decrease in core loss and a slight increase in magnetic induction [89]. However, in 3.0% wt% Si steels, higher Mn content (up to 2.0 wt%) leads to a decrease in magnetic induction and an increase in core loss [90]. Yield strength increases through solid solution strengthening at a rate of around 33 MPa/1 wt% Mn, but it is important to control S content as increased S content adversely affects material properties at each manganese level [91]. To keep Mn in solid solution and prevent Mn precipitations such as oxides and sulphides, very low S and O proportions are essential for Mn-alloyed electrical steels.  
The overall impact of Mn on alloy steels with high silicon content is still a subject of debate due to contradictory findings, especially with respect to steels with low levels of damping elements. In high-alloy steel sheets, manganese increases electrical resistance by approximately 0.062 \(\mu\)\(\Omega\)m/1 wt%Mn, leading to decreased losses at frequencies above 100 Hz due to reduced dynamic iron losses [85].  
Numerous research studies have explored how manganese affects high silicon sheet electric steels with different levels of manganese (0.20%, 0.69%, and 1.38% wt%). The findings indicate that the addition of manganese offers several advantages: it reduces grain size, enhances electrical resistance, and lowers core losses at higher frequencies [91]. To achieve improved magnetic properties, the optimal range of manganese concentrations lies between 0.3% and 1.5% wt% in electrical steel [92]. However, surpassing this range results in undesired effects, such as smaller grains and increased magnetic losses. Interestingly, higher concentrations of manganese lead to a notable reduction in core loss and a slight increase in magnetic flux density [85]. These insights are crucial for optimizing the composition of electrical steels to meet specific industrial and electrical needs.  
In another study, it was demonstrated that manganese could diffuse into steel from a paste containing powdered manganese in a diluted silicone oil solution. The addition of manganese resulted in a remarkable reduction of up to 8% in power loss at 1.5 T in non-oriented 2.4 wt% silicon iron. This reduction can be attributed to a straightforward  
Figure 13: Typical iron losses of 0.35 mm thick CoFe and NiFe alloys at 400 Hz [38].  
increase in resistivity. These findings highlight the potential of manganese as an effective element for enhancing the magnetic properties of no SiFe materials [93].