Aluminum alloy plate excellent in press formability and continuous resistance spot weldability and method for production thereof

Abstract

The invention offers an aluminum alloy plate with excellent press-formability and continuous resistance spot weldability, and a method of manufacturing such a plate. The aluminum alloy plate comprises, in % by mass, 0.3-1.0% of Mg, 0.3-1.2% of Si, 0.10-1.0% of Fe and 0.05-0.5% of Mn; where Fe+Mn≧0.2%; the remainder consisting of Al and unavoidable impurities; wherein an average value of recrystallized grain size is 25 μm or less; and at least 5000 particles/mm 2 of intermetallic compounds with a circle-equivalent diameter of 1-6 μm exist. It can further contain 0.5-1.0% of Cu, 0.1-0.4% of Zr, 0.05% or less of Ti or 0.05% or less of Ti together with 0.01% or less of B. The invention also offers a method of manufacturing an aluminum alloy plate comprising steps of pouring a melt consisting of the above composition into an opposing rotating belt caster that is forcibly cooled; casting the melt at a cooling rate of 40-90° C./sec to form a 5-10 mm thick slab; drawing said slab from the side opposite the side where the melt was poured; rolling directly or after winding into a coil; and subjecting to a solution heat treatment.

1 . An aluminum alloy plate with excellent press-formability and continuous resistance spot weldability comprising, in % by mass, 0.3-1.0% of Mg, 0.3-1.2% of Si, 0.10-1.0% of Fe and 0.05-0.5% of Mn; where Fe+Mn≧0.2%; the remainder consisting of Al and unavoidable impurities; wherein an average value of recrystallized grain size is 25 μm or less; and there are at least 5000 particles/mm 2  of intermetallic compounds with a circle-equivalent diameter of 1-6 μm.  
   
   
       2 . An aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 1 , further comprising 0.5-1.0% of Cu.  
   
   
       3 . An aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 1 , further comprising 0.1-0.4% of Zr.  
   
   
       4 . An aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 1 , further comprising 0.05% or less of Ti, or 0.05% or less of Ti and 0.01% or less of B.  
   
   
       5 . A method of manufacturing an aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 1 , comprising steps of pouring a melt consisting of the above-claimed composition into an opposing rotating belt caster that is forcibly cooled; casting the melt at a cooling rate of 40-90° C./sec to form a 5-10 mm thick slab; drawing said slab from the side opposite the side where the melt was poured; rolling directly or after winding into a coil; and subjecting to a solution heat treatment.  
   
   
       6 . An aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 2 , further comprising 0.1-0.4% of Zr.  
   
   
       7 . An aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 2 , further comprising 0.05% or less of Ti, or 0.05% or less of Ti and 0.01% or less of B.  
   
   
       8 . An aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 3 , further comprising 0.05% or less of Ti, or 0.05% or less of Ti and 0.01% or less of B.  
   
   
       9 . A method of manufacturing an aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 2 , comprising steps of pouring a melt consisting of the above-claimed composition into an opposing rotating belt caster that is forcibly cooled; casting the melt at a cooling rate of 40-90° C./sec to form a 5-10 mm thick slab; drawing said slab from the side opposite the side where the melt was poured; rolling directly or after winding into a coil; and subjecting to a solution heat treatment.  
   
   
       10 . A method of manufacturing an aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 3 , comprising steps of pouring a melt consisting of the above-claimed composition into an opposing rotating belt caster that is forcibly cooled; casting the melt at a cooling rate of 40-90° C./sec to form a 5-10 mm thick slab; drawing said slab from the side opposite the side where the melt was poured; rolling directly or after winding into a coil; and subjecting to a solution heat treatment.  
   
   
       11 . A method of manufacturing an aluminum alloy plate with excellent press-formability and continuous resistance spot weldability in accordance with  claim 4 , comprising steps of pouring a melt consisting of the above-claimed composition into an opposing rotating belt caster that is forcibly cooled; casting the melt at a cooling rate of 40-90° C./sec to form a 5-10 mm thick slab; drawing said slab from the side opposite the side where the melt was poured; rolling directly or after winding into a coil; and subjecting to a solution heat treatment.