24 July 2021 Gear Steel Bar
TL4227 Gear Steel Bar
TL4227 steel is mainly used in the manufacture of high-level auto parts, are special steel, the user of this steel annealing organization and performance has a high demand. Early, due to the user reflects the Baosteel Special Steel production TL4227 steel hardness is high, will give the corresponding impact on the quality of auto parts, and TL4227 steel hardness proposed a new request.
Chemical Composition:
| C | SI | Mn | P | S | Cr | Al | N |
|---|---|---|---|---|---|---|---|
| 0.14~0.22 | ≤0.12 | 1.00~1.50 | ≤0.035 | 0.020~0.035 | 0.80~1.30 | 0.015~0.040 | ≤0.015 |
a) S: In order to improve the machining performance, the drawing can specify the S content of 0.06-0.08%. In this case, the purity requirement A2 does not apply.
b) The ratio of Al to N must be at least 2:1.
Microstructure and physical properties
Purity grade
-The microstructure purity grade is based on the JK scale (Jernkontoret’s Inclusion Chart-Svensk Standard 111116 "Method for Evaluating the Content of Non-metallic Inclusions").
A2 B2 C1 D1
-Total characteristic value K (oxide) test according to DIN 50602.
-17＜d≤35 K3≤35
-35＜d≤70 K4≤30
-70＜d≤140 K4≤40
-Macro tissue purity grade
There are no cracks, rolled slag joints, and the bar must be suitable for forging.
Austenite grain size
Determination of austenite grain size after the following heat treatment:
Initial heat treatment: 40 minutes at 1200 degrees, water quenching or oil quenching;
Heating at t 8/5=(40-60) minutes, austenitizing at 1000°C and water quenching (1000°/4 hours/W).
According to DIN EN ISO 643 (also refer to DIN EN 10084), the grain size after quenching is 5 or finer.
Hardenability
For the determination of hardenability, the formulas in Tables 3a and 3b of SEP 1664:2004-06 are used. Only calculations based on barrel sample analysis are applicable.
J10=(26+17)HRC