According to materials.xml iron is stronger.
Code:
<material id="Miron">
<property name="damage_category" value="metal"/>
<property name="surface_category" value="metal"/>
<property name="forge_category" value="iron"/>
<property name="Hardness" type="float" value="1"/>
<property name="stepsound" value="metal"/>
<property name="stability_glue" value="300"/>
<property name="Mass" type="int" value="20"/>
<property name="explosionresistance" value="1.5"/>
<property name="MaxDamage" value="8000"/>
<property name="Experience" value="2"/>
</material>
<material id="Msteel">
<property name="damage_category" value="metal"/>
<property name="surface_category" value="metal"/>
<property name="forge_category" value="iron"/>
<property name="Hardness" type="float" value="1"/>
<property name="stepsound" value="metal"/>
<property name="stability_glue" value="300"/>
<property name="Mass" type="int" value="20"/>
<property name="explosionresistance" value="1.5"/>
<property name="MaxDamage" value="7000"/>
<property name="Experience" value="6"/>
</material>