S1 Tool Steel - Shock-Resisting Steel (UNS T41901)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
     Forging
     Annealing
     Stress Relieving
     Hardening
     Martempering
Tempering

Introduction

Shock-resisting tool steels are designated as group S steels according to the AISI classification system. S1, S2, S5, S6, and S7 are the types of shock-resisting steels. The hardenability of group S steels can be controlled by varying their composition instead of adjusting the melting procedures and grain size. These steels can obtain optimum hardness at higher austenitizing temperatures. The tempering resistance of group S steels can be enhanced by the addition of silicon, which also forms a microstructure to resist distortion in tempered conditions.

The following section will discuss in detail about S1 shock-resisting tool steels.

Chemical Composition

The following table shows the chemical composition of S1 tool steels.

Element Content (%)
C 0.40-0.55
Mn 0.10-0.40
Si 0.15-1.20
Cr 1.00-1.80
Ni 0.3
Mo 0.5
V 0.15-0.30
Cu 0.25
P 0.03
S 0.03
W 1.50-3.00

Physical Properties

The physical properties of S1 tool steels are given in the following table.

Properties Metric Imperial
Density (@20°C/68°F) 7.89 g/cc 0.285 lb/in3

Mechanical Properties

The mechanical properties of S1 tool steels are tabulated below.

Properties Metric Imperial
Hardness, Rockwell C (air cooled from 899°C, 30 mins) 54.5 54.5
Hardness, Rockwell C (air cooled from 927°C, 30 mins) 56 56
Hardness, Rockwell C (air cooled from 982°C, 30 mins) 56.5 56.5
Modulus of elasticity 207 GPa 30000 ksi
Charpy impact (V-notch; oil quenched from 954°C; 149°C temper temperature) 10.8 J 8.00 ft-lb
Charpy impact (V-notch; oil quenched from 954°C; 625°C temper temperature) 29.8 J 22.0 ft-lb
Machinability (1% carbon steel) 70.0 - 75.0% 70.0 - 75.0%
Poisson's ratio 0.27-0.30 0.27-0.30

Thermal Properties

The following table shows the thermal properties of S1 tool steels.

Properties Conditions
T (°C) Treatment
Thermal expansion 12.4 x 10-6/ºC 20-100 -

Other Designations

Other designations that are equivalent to S1 tool steels include:

  • AFNOR 55 WC 20
  • DIN 1.2550
  • UNI 58 WCr 9 KU
  • ASTM A681
  • FED QQ-T-570
  • SAE J437
  • SAE J438
  • UNS T41901
  • ASTM A681
  • DIN 1.2542

Fabrication and Heat Treatment

Forging

S1 tool steels are uniformly preheated at 1000°C (1832°F). These steels are then forged at temperatures ranging from 800 to 1000°C (1472 to 1832°F). This process is followed by cooling in a furnace to avoid stress.

Annealing

Annealing is carried out in S1 tool steels by uniformly heating the steels to 770°C (1418°F) followed by equalization. These steels are then cooled in the furnace.

Stress Relieving

S1 tools steels are heated up to 700°C (1292°F) before hardening, equalized, and then slowly cooled in order to remove stresses during heavy machining operations.

Hardening

S1 tools steels are preheated to 650°C (1202°F) and soaked. They are then continuously heated to the final temperature that ranges from 900 to 950°C (1652 to 1742°F). Finally, the steels are quenched in oil.

Martempering

Martempering is performed in the case of S1 tool steels as an alternative procedure for hardening. This is carried out in a salt bath equipment.

Tempering

S1 tool steels are tempered by uniformly heating the steels at the preferred tempering temperature followed by holding for an hour.

Comments

  1. Vedant Bhayani Vedant Bhayani India says:

    I am continually use S 1 toll steel to crop 6 to 16 mm angles. With 54 to 56 HRC . Is it ok or need to changes?
    I have received better results in round hole punching then cropping. You can give me suggestions to improve life of tools.
    I m tool manufacturer , so it is my first requirement.

    • Keyur Bhayani Keyur Bhayani India says:

      it is ok

  2. naga arjun naga arjun India says:

    HELLO!!!!! EVERYONE  iam nagarjun i need help.where i can get this material in india r chennai. and also i need price for 1kg. please kindly reply me.

    • Keyur Bhayani Keyur Bhayani India says:

      300 rs/kg

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoM.com.

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