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THYROPLAST

®

 2312 (Ultra Holder) 

Technical Data Sheet 

Chemistry 

Comparable Standard: DIN 1.2312   
Typical  

Mn 

Cr 

Mo 

  S 

             

Analysis %         0.4           1.5         1.9          0.2 

0.05        

Description 

•  THYROPLAST

®

 2312 is a pre-hardened single melt Extra Fine 

Structure (EFS) plastic mold steel. 

•  Re-sulphurized to improve machinability 

•  Supplied hardness of 280—325 HB (29-34 HRC) 

Characteristics 

•  Excellent machinability compared to THYROPLAST

®

  2311 

Applications 

• 

Injection molds where surface finish is not critical 

• 

Mold bases 

• 

Die holders 

• 

Ejector plates 

• 

Rubber molds 

Physical Properties 

 

 
 
 
 

Coefficient of 

Thermal  

Expansion

 

  

70

0

F – 200

0

F 

6.8 X 10

-6

 /

0

70

0

F – 400

0

F 

7.2 X 10

-6

 /

0

70

0

F – 575

0

F 

7.6 X 10

-6

 /

0

Thermal  

Conductivity

 

  

212

0

F 

276 Btu/in/ft

2

/

hr/

0

400

0

F 

280 Btu/in/ft

2

/

hr/

0

575

0

F 

270 Btu/in/ft

2

/

hr/

0

Heat Treatment 

Welding 

Soft Annealing 

 

Tempering (See tempering diagram below) 

 

•  Tempering hardness is approximate and based on two hours at 

temperature 

•  Please contact your Schmolz & Bickenbach heat treat representa-

tive for more detailed in

formation.

 

Temperature 

Cooling 

Hardness 

1310 

o

F - 1365

o

F Furnace 

 

235 HB 

Max 

Temperature 

o

F 

212

 

392

 

572

 

752

 

932

 

1112

 

Hardness

 

HRC 

51

 

50

 

48

 

46

 

42

 

36

 

1292 

28 

Polishing 

 THYROPLAST

®

 2312  is primarily used as a holder material for 

plastic molds and for die casting dies.  It is not intended for tools 
which require a high surface finish.  A Schmolz & Bickenbach 

representative should be consulted

 for additional information 

Density: 0.283 lbs/in

(room temperature) 

Mechanical Properties 

Hardness 

HRC 

51 50 48 46 42 36 

28 

Tensile 

Strength 

KSI 

251 242 228 215 193 165 

134 

32 

123 

All statements regarding the properties or utilization of the materials or 
products mentioned are for the purposes of description only.  Guarantees 
regarding the existence of certain properties or a certain utilization are 

General Note 

•  Preheat insert to 600

0

F to 700

0

F.  Maintain temperature above 

600

0

F during welding.   

•  Use TIG with D.C. positive polarity. 

•  Depending on the application, various welding rods can be used.   

P20 filler which will match the hardness of the base metal after 
welding and tempering is commonly used.  Please contact our 
heat treatment facility for recommendations. 

•  Slowly cool down to 100

0

F– 150

0

F , preferably under an insulat-

ing blanket, before post heat. 

•  Post heat at 1000

0

F

 

one hour per inch of weld depth plus one ad-

ditional hour—double temper if possible.  Exceeding 1050

0

could result in the loss of hardness. 

Tempering Diagram 

30

34

42

38

46

50

54

58

62

66

70

212 392 572 752 932 1112

0

1292 1472

Har

dness in HRC

Temperature °F

USA 800.323.1233  

CANADA 800.268.4977  

HEAT TREATMENT 800.265.0862 

 

www.schmolz-bickenbach.us 

   www.schmolz-bickenbach.ca