Engineering Machinery Steel
The engineering machinery steel are mainly applied to the mechanical equipments demanded by the companies specialized in machinery, coal, transportation, mine and every kind of construction, such as drilling machine, electric furnace, electric tipper, excavator, loader, earthmover, all kinds of hoisting equipment and mining hydraulic support etc. It not only owns considerable high strength, but also has high wear-resistance, plasticity and good weldablity. Product with grade LG600, LG700, LG700T, LG700QT, LG900QT 、LG960QT、LG1100QT can be supplied.
 
Delivery Standard

Category	Steel Grade	Standard	Application
Engineering Machinery Steel	LG600、LG700、LG700T、LG700QT、LG900QT、LG960QT、LG1100QT	Agreement	The product is used for autocrane jib,turnable autocrine jib, ridge beam of lengthened (weighted) container, heavy engineering structure part, heavy automotive structure etc.
High Strength Structural Steel	Q390、Q420、Q460、Q500、Q550、Q620、Q690、Q800、Q890、Q960 、Q1100	GB/T 16270-2009	Has high strength and good plasticity. Widely used in equipment structures and welding structure parts of bridge making, chemical industry, engineering machinery etc.
Steel for ATM Machine	LG600A	User Agreement	ATM Machine Cabinet

 
Product Precision:
Length: 0-10mm in accordance with the sheet length.
Width: 0-6mm for the sheet with side trimming, the width shall be controlled by mill for the sheet without side trimming.
Profile: the unflatness of the sheet≤5mm within 1000mm.
The stress shall be released through high straightening force and high deformation force.
 
Main Applications:
The engineering machinery steel of LY Steel are mainly applied to the equipments demanded by the companies specialized in machinery, coal, ATM machine, transportation, mine and every kind of construction, such as electric tipper, crane and coal hydraulic support etc.



Main Features:
1、Low carbon chemistry design is adopted with low carbon equivalent CEQ and cold crack sensitivity PCM.
2、The product has good low temperature toughness after welding, which can reach to 50J with the impact un- der -40℃.
3、The weld joint has good cold bending plasticity, for the 900MPa above grade, the surface remains good when the bending diameter is 6 times of the thickness with 90°bending under normal temperature.
4、The product has good weldability, the butt welding, overlap welding and angle joint welding, etc. with medium restriction can be carried out under normal temperature without being preheated.

 
Welding and Processing
Hot-rolled  high-strength  steel  possesses  good weldability through low-carbon and low-alloy design to decrease carbon equivalent and cracking sensibility index, and advanced smelting equipment and technology integrated with micro-alloy strengthening technology.

 
Cracking Sensitivity Test of Welding
According to CTS test, all the rates of crack are 0% which proves that there are almost no cracks for high-strength steel during all kinds of welding with the temperature of above 0℃.
 
Hardness of Welded Joint
The maximum hardness of welded joint of high-strength steel is less than HV350, and HAZ exists in softened zone which is relatively narrow. It is better to take low heat input and quick welding to narrow the width of softened zone.
 
Welding Parameter
When the ambient temperature is higher than 0℃ , high strength steel plate can be welded directly without being preheated, and cold cracks are difficult to generate. MAG is recommended for welding. And it is better to use 80%Ar+20%CO as welding gases with flow rate 18~25l/min. 
The recommended welding wire is applied to all-position welding.   
Upward welding is recommended during welding in vertical position, so as to avoid welding defects. Hot rolled high strength steel is applicable to various types of welding joint. Common joint types are butt joint, angle joint and overlap joint. Common groove weld types are I groove, V groove and double V groove. During welding, if incomplete penetration occurred, check that whether the gap is big enough and arc is perpendicular to the plate surface.
Backing weld can be used in droplet transfer with smaller parameters, that is small current and voltage with quick welding. As to the crucial structure, TIG can be used as backing weld. To avoid crack during fixed-position welding, weld length should be at least longer than 50mm with droplet transfer of bigger parameters. As to MAG, take weld wire φ1.2mm as an example, typical welding parameters of backing weld are 100~200A，12-19V，2.5~7mm/s; Typical parameters of fixed-location weld are 200~250A，20~23V，4.0~6.5mm/s.
Droplet transfer and spray transfer with bigger parameters can be used in filling and cosmetic welding. As to MAG, take weld wire φ1.2mm as an example, typical welding parameters recommended to filling and cosmetic welding are 200~250A，20~23V，4.0~6.5mm/s (droplet transfer).
 
Recommended Process Parameters of Welding

Steel Grade	Thickness of Flitch Plate (mm)	Heat Input Range (KJ/cm)	Recommended Parameters
			Current (A)	Voltage (V)	Gas Flow Rate (L/min)	Welding Stick Recommended
Q460	3-25	4-15	150-250	15-25	15-25	ER70-6
LG600	3-12	4-10	150-250	18-25	15-20	ER90-G
LG700 LG700T LG700E	3-12	4-10	150-250	18-25	15-20	ER100S-G
LG600A	12-13	5-12	150-200	15-25	10-20	KOBELCO Steel KM-60AS
LG900QT LG960QT	4-20	5-8	100-200	15-25	18-23	ER120S-G