Description

SM50 steel is a carbon plastic mold steel. Its chemical composition is similar to that of high-strength medium-carbon high-quality structural steel-50 steel. However, the cleanliness of the steel is higher, the fluctuation range of carbon content is narrower, and the mechanical properties are more stable. The steel has certain hardness, strength and wear resistance after normalizing or quenching and tempering. The price is cheap and the cutting performance is good.

SM50

SM50 Steel Chemical Composition

CSiMnPS
0.47~0.530.17~0.370.50~0.80≤0.030≤0.030

SM50 Steel Mechanical Properties

Proof strength
Rp0.2(MPa)
Tensile strength
Rm(MPa)
Impact energy
KV(J)
Elongation at fracture
A(%)
Reduction in cross section on fracture
Z
(%)
As-Heat-Treated ConditionBrinell Hardness(HBW)
521(≥)756(≥)121123Solution and Aging,Annealing,Ausaging,Q+T,etc313

SM50 Steel Physical Properties

PropertyDensity
kg/dm3
Temperature T
°C/F
Specific heat
J/kgK
Modulus of elasticity
kN/mm2
959(≥)283(≥)3333114
Temp.
°C/°F
Creep strain limit
(10000h)
(Rp1,0)N/mm2
Creep rupture strength
(10000h)
(Rp1,0)N/mm2
Thermal conductivity
W/mK
Electric resistance
µΩ·cm
73489581332Solution and Aging,Annealing,Ausaging,Q+T,etc

Heat Treatment 

Critical temperature of SM50 steel

Critical pointAc1Ac3Ar3Ar1
Temperature (approximate) / ℃725760720690

Fully annealed

Heating at 810~830℃. Insulation, furnace cooling, hardness is 197~225HBS. The heating temperature is above the Ac3 line to get the pearlite + ferrite structure

Normalizing

Heating at 820~870℃. Heat preservation, air cooling, hardness is 217~248HBS, heating temperature is above the Ac3 line, refine grains, eliminate structural defects, and get pearlite + a small amount of ferrite structure

Quenching

Heating at 820~850℃. Insulation, water-oil cooling, hardness is 55~58HRC. Water cooling prevents tissue transformation at high temperatures and reduces thermal stress. Oil cooling reduces phase transformation stress and prevents deformation and cracking

Tempering

Heating at 200~600℃. Heat preservation for 2h, air cooling, hardness is 23~56HRC.

Tempering temperature/℃200300500550600
Tempering hardness/HRC5651423323

Features and Application


SM50 alloy steel is high-strength medium-carbon steel. It has low cold deformation plasticity, poor weldability and hardenability. But, it has no temper brittleness and general cutting performance. Use under normalizing or quenching and tempering. It is used to manufacture machined parts and spring parts with little dynamic load and impact. Such as forged gears, tie rods, rolls, shafts, friction discs, agricultural excavation ploughshares, heavy duty mandrels.

SM50 Products

Product typeProductsDimensionProcessesDeliver Status
Plates/SheetsPlates/Sheets0.08-200mm(T)*W*LForging, hot rolling, and cold rollingAnnealed, Solution and Aging, Q+T, ACID-WASHED, Shot Blasting
Steel BarRound Bar, Flat Bar, Square BarΦ8-1200mm*LForging, hot rolling and cold rolling, CastBlack, Rough Turning, Shot Blasting,
Coil/StripSteel Coil/Steel Strip0.03-16.0x1200mmCold-Rolled&Hot-RolledAnnealed, Solution and Aging, Q+T, ACID-WASHED, Shot Blasting
Pipes/TubesSeamless Pipes/Tubes, Welded Pipes/TubesOD:6-219mm x WT:0.5-20.0mmHot extrusion, Cold Drawn, WeldedAnnealed, Solution and Aging, Q+T, ACID-WASHED