NADCA Specifications for Die Steels

NADCA 207-2003

NADCA 207-2003 introduced two acceptance levels for AISI H13 for the die casting industry: the premium level and the superior level.

Premium Level

The premium criteria for H13 material under the NADCA 207-2003 specification does not deal with the steel making practices or the forging practices of the steel manufacturer. Rather the specification calls for improved levels of cleanliness, a reduction in micro and macro banding, and for certification of impact toughness levels for material capability at an 8 ft-lbs average with a 6 ft-lbs single minimum value. Combined with NADCA recommended vacuum austenitizing and pressurized gas quenching choosing steels that meet this specification can lead to success in production in the die-casting process. Now known as NADCA Grade A.

Superior Level

When dealing with superior grade H13, the steel making process needs to include secondary refining, either ESR (electro-slag remelting) or VAR (vacuum arc remelting). Additionally the specification calls for improved levels of cleanliness, a reduction in micro and macro banding, and for certification of impact toughness levels for material capability at a 10 ft-lbs average with 8ft-lbs single minimum value. This type of manufacturing technique combined with NADCA recommended vacuum austenitizing and pressurized gas quenching can lead to success in production where high volume production or critical performance in the die casting process is required. Now known as NADCA Grade B.

NADCA 207-2008

While H13 is good for most general applications in die casting, alternative grades are available that can address specific needs within the die casting environment. NADCA 207-2008 combines the specifications for Premium and Superior Levels of H13 from NADCA 207-2003, and adds additional controls for other hot work tool steels. All of the alternative grades must be remelted.

Grade A: The premium level of H13 is now referred to as NADCA Grade A.

Uddeholm Orvar Supreme and Bohler W302 Isobloc meet the requirement for NADCA Grade A

Grade B: The superior level of H13 is now referred to as NADCA Grade B.

Uddeholm Orvar Superior and Bohler W302 Superior meet the requirement for NADCA Grade B

Grade C: In applications where higher temper resistance is required to minimize the loss of hardness at elevated temperatures, there are hot work tool steels available to improve the die's performance. These grades are based on a 1.2367 chemistry, but they have been enhanced to improve performance as a die casting material.

Uddeholm Dievar and Bohler W403 VMR meet the requirement for NADCA Grade C

Grade D: In applications where high toughness is required due to gross cracking or heat checking issues, but temper resistance is not as critical, an H11 type alloy can be considered. These hot work tool steels have a capability requirement of 14ft-lbs minimum average Charpy V-notch toughness at 44-46HRC. These grades are also required to be remelted, which further adds to the overall uniformity of the product.

Uddeholm Vidar Supreme and Bohler W300 Isobloc meet the requirement for NADCA Grade D.

Grade E: This category of hot work tool steels contains those grades which have been modified to enhance the characteristics of the H11 type alloy. Therefore, these grades are modifications to those alloys contained in Grade D. Further enhancing the toughness of the H11 family, these grades contain some of the toughest hot work tool steel grades. Modifications to the refining process through enhanced remelting, and the chemistry changes make this possible.

Uddeholm Vidar Supreme and Bohler W400 VMR meet the requirement for NADCA Grade E