A2 Tool Steel

One. Product Description

A2 Tool Steel is the most common grade of rebar used to make tools for forming metal, wood, and other materials. A2 medium carbon chromium alloy steel is a member of the cold work tool steel group designated by the American Iron and Steel Institute (AISI), including O1 low carbon steel, A2 steel and D2 high carbon high chromium steel.

A2 Tool Steel is a general purpose air hardening tool steel characterized by good toughness and excellent dimensional stability during heat treatment. The wear resistance of A2 tool steel is between that of O1 oil hardening tool steel and D2 high carbon and high chromium tool steel. A2 tool steel offers an effective combination of strength and toughness, tool performance, price and multiple product forms.

Two. Quality Standard

ASTM A681 Standard Specification

Three. Product Specifications

Four. Equivalent Grade of A2 Tool Steel - For Reference Only

Five. Product Features and Uses

Features:

1. Good machinability and grindability. Better machinability and grindability than SKD11, resulting in longer tool life and fewer machining hours.

2. Heat treatment advantage Quenching hardening energy is higher than SKD11, which can improve the defect of insufficient hardness during vacuum heat treatment.

3. Advantages of wire cutting process High temperature tempering can reduce residual stress, eliminate residual wrought iron, and prevent the trouble of cracking and deformation during wire cutting.

4. Advantages of surface hardening treatment After surface hardening treatment, the surface hardness is higher than SKD11, so the mold performance can be improved.

5. Advantages of repair welding operation Because the preheating and post heating temperature is lower than SKD11, repair welding operation is simpler, and small plastic molds can be provided.

Use:

Punch and mold, jigs, wood cutting tools, plastic injection tools, dowels, hammers, industrial knives and gauges A2 rebar comes in a variety of forms including square, round and rectangular. This highly versatile material can be used in a variety of tools that require wear resistance, such as industrial hammers, knives, slitters, punches, tool holders and woodworking cutting tools.

For blades and blades, A2 steel resists chipping and therefore lasts longer, generally making it a more economical choice than high carbon D2 steel. Commonly used for blanking of thread rolling molds, stamping molds, trimming molds, injection molds, mandrels, molds, and spindles.

Six. Product Detailed Information

A2 tool steel is also an air hardening tool steel, but it has less than half the chromium content (4.75–5.50%) of D2 steel and slightly lower carbon content (0.95–1.05%). It has a high degree of wear resistance and moderate toughness. Like D2 steel, it is incredibly resistant to deformation during heat treatment and can be moderately machined and ground.

Common hardness ranges for A2 tool steels are between 57–62 HRC and yield strengths in the range of 185 ksi–230 ksi.

Smelting Options

1. EAF: electric arc furnace.

2. EAF+LF+VD: refining-vacuum degassing.

3. EAF+ESR: electroslag remelting.

4. EAF+PESR: protective atmosphere electroslag remelting.

5. VIM+PESR: vacuum induction melting.

Molding Options

1. Rolling process.

2. Hot forging, electro-hydraulic, high-speed hydraulic, hydraulic, precision forging.

Heat Treatment Scheme

1. +A: Annealing (Full/Soft/Sphericalized).

2. +N: Standardization.

3. +NT: normalizing and tempering.

4. +QT: conditioning (water/oil).

Physical Properties

Density: 0.284 lb/in3 (7861 kg/m3).

Specific gravity: 7.86.

Elastic modulus: 30x106 psi(207GPa) (207GPa W/m/°K).

Machinability: 70% of 1% carbon steel.

Heat Treatment Instructions

Hardening

Critical temperature: Ac1: 1460℉ (793℃).

Preheat: Heat to 1150-1250°F (621-677°C) at a rate not to exceed 400°F per hour (222°C per hour) and equilibrate. Then heat to 1300-1400℉ (704-760℃).

Austenitizing (high temperature): Slow heating from preheating. Furnace or Salt: 1725-1750°F (941-954°C) for 30 minutes, 1 inch (25.4 mm) thick, 15 minutes for each 1 inch (25.4 mm) increment.

Quenching: Air, pressurized gas, or intermittent oil to 150-125°F (66-51°C).

Note: Dimensions over 3" (76.2mm) cross-section may not be cooled to full hardness in still air. Quenching cooling rates usually need to be increased to between 1400 and 900°F (760 and 482°C) by use of blast air , pressurized gas or intermittent oil quenching. For oil quenching, quench to black, approximately 900°F (482°C), then cool in still air to 150-125°F (66-51°C).

Tempering: Temper immediately after quenching. Hold at this temperature for 1 hour per inch (25.4mm) of thickness, a minimum of 2 hours, then air cool to ambient temperature. Typical tempering range is 350 to 500°F (177 to 260°C), in order to minimize internal stress in cross-sections larger than 6 inches (152.4mm) and to improve the stability of tools that will be EDMed after heat treatment, strong Soaking for 4 to 6 hours at tempering temperature is recommended.

Cryogenic treatment: Some prefer low temperature treatment as an extension of the austenitizing quench. Others prefer a low temperature treatment after tempering.

Annealing

Annealing must be done after hot working and before rehardening.

Heat to 1550°F (843°C) at a rate not to exceed 400°F (222°C per hour) and hold at that temperature for 1 hour per inch (25.4 mm) of maximum thickness; 2 hours minimum. Then cool slowly in the furnace to 1000°F (538°C) at a rate not to exceed 50°F (28°C) per hour. Continued cooling to ambient temperature in the furnace or in air should result in a maximum hardness of 235 HBW.

Nitriding

Nitriding will form a hard diffused surface layer that is very wear and corrosion resistant and also increases corrosion resistance. The surface hardness of AISI A2 steel nitrided in ammonia water at 975℉ (525℃) is about: 1000 HV1.