Effects of Common Alloying Elements

Effects of Common Alloying Elements in Steel



By definition, steel is a combination of iron and carbon. Steel is alloyed with various elements to improve physical properties and to produce special properties such as resistance to corrosion or heat. Specific effects of the addition of such elements are outlined below:

Carbon (C)

The most important constituent of steel. It raises tensile strength, hardness, and resistance to wear and abrasion. It lowers ductility, toughness and machinability.

Chromium (CR)

Increases tensile strength, hardness, hardenability, toughness, resistance to wear and abrasion, resistance to corrosion, and scaling at elevated temperatures.

Cobalt (CO)

Increases strength and hardness and permits higher quenching temperatures and increases the red hardness of high speed steel. It also intensifies the individual effects of other major elements in more complex steels.

Columbium (CB)

Used as stabilizing elements in stainless steels. Each has a high affinity for carbon and forms carbides, which are uniformly dispersed throughout the steel. Thus, localized precipitation of carbides at grain boundaries is prevented.

Copper (CU)

In significant amounts is detrimental to hot-working steels. Copper negatively affects forge welding, but does not seriously affect arc or oxyacetylene welding. Copper can be detrimental to surface quality. Copper is beneficial to atmospheric corrosion resistance when present in amounts exceeding 0.20%. Weathering steels are sold having greater than 0.20% Copper.

Manganese (MN)

A deoxidizer and degasifier and reacts with sulfur to improve forgeability. It increases tensile strength, hardness, hardenability and resistance to wear. It decreases tendency toward scaling and distortion. It increases the rate of carbon-penetration in carburizing.

Molybdenum (MO)

Increases strength, hardness, hardenability, and toughness, as well as creep resistance and strength at elevated temperatures. It improves machinability and resistance to corrosion and it intensifies the effects of other alloying elements. In hot-work steels and high speed steels, it increases red-hardness properties.

Nickel (NI)

Increases strength and hardness without sacrificing ductility and toughness. It also increases resistance to corrosion and scaling at elevated temperatures when introduced in suitable quantities in high-chromium (stainless) steels.

Phosphorus (P)

Increases strength and hardness and improves machinability. However, it adds marked brittleness or cold-shortness to steel.

Silicon (SI)

A deoxidizer and degasifier. It increases tensile and yield strength, hardness, forgeability and magnetic permeability.

Sulfur (S)

Improves machinability in free-cutting steels, but without sufficient manganese it produces brittleness at red heat. It decreases weldability, impact toughness and ductility.

Tantalum (TA)

Used as stabilizing elements in stainless steels. Each has a high affinity for carbon and forms carbides, which are uniformly dispersed throughout the steel. Thus, localized precipitation of carbides at grain boundaries is prevented.

Titanium (TI)

Used as stabilizing elements in stainless steels. Each has a high affinity for carbon and forms carbides, which are uniformly dispersed throughout the steel. Thus, localized precipitation of carbides at grain boundaries is prevented.

Tungsten (W)

Increases strength, wear resistance, hardness and toughness. Tungsten steels have superior hot-working and greater cutting efficiency at elevated temperatures.

Vanadium (V)

Increases strength, hardness, wear resistance and resistance to shock impact. It retards grain growth, permitting higher quenching temperatures. It also enhances the red-hardness properties of high-speed metal cutting tools.

Data is typical and should not be construed as actual values for any catagory.
Applications and technical information require engineers and tool designers to exercise independent judgement.

Table – Hardness Conversion

Hardness Conversion Table

RELATIONSHIP BETWEEN BRINELL, ROCKWELL, AND TENSILE STRENGTH FOR TOOL AND ALLOY STEELS
3000 KG. LOAD 10 MM BALL C SCALE B SCALE 1000 POUNDS PER SQ. IN. 3000 KG. LOAD 10 MM BALL C SCALE B SCALE 1000 POUNDS PER SQ. IN.
IMP. DIA. M M. HARD NESS NO. 150 KG. SCALE 100 KG. BALL IMP. DIA. MM. HARD- NESS NO. 150 KG. SCALE 100 KG. BALL
2.20 780 68 382 4.15 212 17 95 104
2.25 745 66 365 4.20 207 16 95 101
2.30 712 65 349 4.25 201 15 94 99
2.35 682 63 334 4.30 197 14 93 97
2.40 653 62 320 4.35 192 13 92 95
2.45 627 60 307 4.40 187 11 91 93
2.50 601 58 294 4.45 183 10 90 91
2.55 578 57 283 4.50 179 9 89 89
2.60 555 55 272 4.55 174 7 88 87
2.65 534 53 261 4.60 170 6 87 85
2.70 514 52 252 4.65 167 5 86 84
2.75 495 50 242 4.70 163 3 85 82
2.80 477 49 234 4.75 159 2 84 80
2.85 461 48 226 4.80 156 1 83 79
2.90 444 46 217 4.85 152 0 82 77
2.95 429 45 210 4.90 149 81 75.
3.00 415 44 203 4.95 146 80 74
3.05 401 42 196 5.00 143 79 72
3.10 388 41 112 190 5.05 140 78 71
3.15 375 40 111 184 5.10 137 77 70
3.20 363 39 110 178 5.15 134 75 69
3.25 352 38 109 172 5.20 131 74 67
3.30 341 37 108 167 5.25 128 73 66
3.35 331 36 108 162 5.30 126 72 65
3.40 321 35 107 157 5.35 123 71 63
3.45 311 34 106 152 5.40 121 70 62
3.50 302 33 106 148 5.45 118 68 61
3.55 293 32 105 144 5.50 116 67 60
3.60 285 30 104 140 5.55 114 66 58
3.65 277 29 104 136 5.60 111 65 57
3.70 269 28 103 132 5.65 109 63 56
3.75 262 27 102 128 5.70 107 62 55
3.80 255 26 101 125 5.75 105 60 54
3.85 248 25 100 122 5.80 103 58 53
3.90 241 23 100 118 5.85 101 58 52
3.95 235 22 99 115 5.90 99 56 51
4.00 229 21 98 112 5.95 97 55 50
4.05 223 20 97 109 6.00 95 54 49
4.10 217 18 96 106
Data is typical and should not be construed as actual values for any category.
Applications and technical information require engineers and tool designers to exercise independent judgement.

Welding of Tool Steel

Welding of Tool Steel

It is sometimes necessary to weld finished or partly finished tool steel parts. Welding tool steels differs from welding the low carbon machinery steels since tool steels, because of their alloy content and the welding temperatures will actually harden to maximum hardness in and near the area welded. Such localized hardening can cause severe cracking and it is, therefore, necessary that all possible precautions be taken to prevent, or at least reduce, the stresses that cause this cracking.

We offer the following suggestions for optimum results in the welding of tool steel parts with the warning that as the alloy content and the hardness of the steel to be welded increases the danger of post-weld cracking increases. Note also that while the heat of welding will harden the higher alloy tool steels, it may actually soften the lower alloy grades to an unacceptable degree and the part may have to be re-heat treated after welding. Even in the higher alloys there will be a soft or overtempered zone between the weld and the base metal, but in these grades this soft zone is generally acceptable.

PROCEDURE

Preheat the part to as high a temperature as is consistent with the final hardness requirements, preferably in the range of 400-1000F (250-538C). The preheat temperature for hardened tools should not exceed the original draw temperature.  Furnace preheating is desirable but torch preheat is widely practiced. Welding may then be performed using either shielded arc techniques (Heliarc or Atomic Hydrogen) with uncoated tool steel welding wire or electric arc methods using specially coated electrode.

Often a stainless rod is used for non-critical areas. After welding, equalize in a furnace at the preheat temperature and cool slowly to room temperature. Following this you must slow cool with a tempering treatment at a temperature just below the original tempering temperature.  Postheat hardened tools for 1 hour per inch, 2 hours minimum, at 50F below the original tempering temperature.  Annealed tools should be re-annealed.  This serves both as a stress relieving operation as well as to minimize the hardness gradient across the weld area. Local conditions may vary the welding methods, but the principle of preheating and slow cooling should be respected to minimize risks.

Data is typical and should not be construed as actual values for any category.
Applications and technical information require engineers and tool designers to exercise independent judgement.

Grade Compositions

Grade Compositions

Grade C CO CR MN MO NI P S SI V W
1018 Cold Roll0.15 - 0.20 0.60 - 0.90 0.04 Max.0.05 Max.
4100.15 Max. 11.50 - 13.501.00 Max. 0.40
4140 Annealed0.38 - 0.43 0.80 - 1.100.75 - 1.000.15 - 0.25 0.04 Max.0.04 Max.0.14 - 0.35
4140 Heat Treated0.38 - 0.43 0.80 - 1.100.75 - 1.000.15 - 0.25
4140 Super Brake Die0.37 - 0.44 0.75 - 1.200.75 - 1.000.15 - 0.25 0.04 Max.0.04 Max.0.14 - 0.35
4150 Heat Treated0.48 - 0.53 0.80 - 1.100.75 - 1.000.15 - 0.25 0.04 Max.0.04 Max.0.15 - 0.30
4200.15 Min. 12.00 - 14.501.00 Max. 1.00 Max.0.30
43400.38 - 0.43 0.70 - 0.900.65 - 0.850.20 - 0.301.65 - 2.000.04 Max.0.04 Max.0.15 - 0.30
440C0.95 - 1.20 16.00 - 18.001.00 Max.0.75 Max. 0.04 Max.0.03 Max.1.00 Max.
61500.48 - 0.53 0.80 - 1.100.70 - 0.90 0.04 Max.0.04 Max.0.15 - 0.300.15 Min.
86200.18 - 0.23 0.40 - 0.600.70 - 0.900.15 - 0.250.40 - 0.700.04 Max.0.04 Max.0.15 - 0.30
A-101.25 - 1.50 1.60 - 2.101.25 - 1.751.55 - 2.05 1.00 - 1.50
A-20.95 - 1.05 4.75 - 5.500.40 - 1.000.90 - 1.40 0.10 - 0.500.15 - 0.50
A-36 Hot Roll Plate0.25 0.80 - 1.20 0.04 Max.0.05 Max.0.40 Max.
A-36 XL Plate0.25 0.80 - 1.20 0.04 Max.0.05 Max.0.40 Max.
A-60.65 - 0.75 0.90 - 1.401.80 - 2.500.90 - 1.40 0.10 - 0.70
A-80.50 - 0.60 4.75 - 5.500.20 - 0.501.15 - 1.65 0.03 Max.0.03 Max.0.75 - 1.10 1.00 - 1.50
CPM 10V®2.45 5.25 1.30 9.75
CPM 15V®3.40 5.250.501.30 0.070.9014.50
CPM 1V®0.55 4.50 2.75 1.002.15
CPM 3V®0.80 7.50 1.30 2.75
CPM 9V®1.80 5.250.501.30 0.909.00
CPM REX 76®1.508.503.750.30 Min.5.25 0.06 Min.0.303.109.75
CPM REX M-4®1.30 4.000.304.50 0.03 Max.0.304.005.50
CPM REX T-15®1.605.004.000.30 0.06 Min.0.304.9012.00
CPM S90V®2.30 14.00 1.00 9.00
D-21.40 - 1.60 11.00 - 13.000.10 - 0.600.70 - 1.20 0.10 - 0.600.50 - 1.10
D-72.15 - 2.50 11.50 - 13.500.10 - 0.600.70 - 1.20 0.10 - 0.603.80 - 4.40
H-110.33 - 0.43 4.75 - 5.500.20 - 0.601.10 - 1.60 0.80 - 1.250.30 - 0.60
H-130.32 - 0.45 4.75 - 5.500.20 - 0.601.10 - 1.75 0.80 - 1.250.80 - 1.20
L-60.65 - 0.75 0.60 - 1.200.25 - 0.800.501.25 - 2.000.03 Max.0.03 Max.0.500.20 - 0.30
Low Carbon0.15 - 0.25 0.60 - 1.20 0.04 Max.0.05 Max.
M-20.78 - 1.05 3.75 - 4.500.15 - 0.404.50 - 5.500.30 Max.0.03 Max.0.03 Max.0.20 - 0.451.75 - 2.205.50 - 6.75
M-41.25 - 0.14 3.75 - 4.750.15 - 0.404.25 - 5.50 0.20 - 0.453.75 - 4.505.25 - 6.50
M-421.05 - 1.157.75 - 8.753.50 - 4.250.15 - 0.409.00 - 10.00 0.15 - 0.650.95 - 1.351.15 - 1.85
O-10.85 - 1.00 0.40 - 0.701.00 - 1.40 0.10 - 0.500.30 Max.0.40 - 0.60
O-61.25 - 1.55 0.30 Max.0.30 - 1.100.20 - 0.30 0.55 - 1.50
P-200.28 - 0.40 1.40 - 2.000.60 - 1.000.30 - 0.55 0.03 Max.0.03 Max.0.20 - 0.80
P-20 HI HARD0.28 - 0.40 1.40 - 2.000.60 - 1.000.30 - 0.55 0.03 Max.0.03 Max.0.20 - 0.80
P-20-320.28 - 0.40 1.40 - 2.000.60 - 1.000.30 - 0.55 0.03 Max.0.03 Max.0.20 - 0.80
S-10.40 - 0.55 1.00 - 1.800.10 - 0.400.50 Max. 0.03 Max.0.03 Max.0.15 - 1.200.15 - 0.301.50 - 3.00
S-50.50 - 0.65 0.10 - 0.500.60 - 1.000.20 - 1.35 1.75 - 2.250.15 - 0.35
S-70.45 - 0.55 3.00 - 3.500.20 - 0.901.30 - 1.80 0.20 - 1.000.35 Max.
T-10.65 - 0.80 3.75 - 4.500.10 - 0.40 0.20 - 0.400.90 - 1.3017.25 - 18.75
T-151.50 - 1.604.75 - 5.253.75 - 5.000.15 - 0.401.00 Max. 0.15 - 0.404.50 - 5.2511.75 - 13.00
VERTEX1.00 8.250.502.25 1.000.40
W-10.70 - 1.50 0.15 Max.0.10 - 0.400.10 Max. 0.10 - 0.400.10 Max.0.15 Max.

Designing Tools to Avoid Failure

Designing Tools to Avoid Failure

Tools and machine parts made from tool steels are often subjected to high stress in operation. These parts also have a certain amount of internal stress as a result of their fabrication and heat treatment. When these stresses, either singly or in combination, exceed the strength limits of the steel, cracking, breaking or warping of the part results. Many fully hardened tool steels, particularly highly alloyed types, can withstand relatively high compressive loading, but only limited tensile loading. Tool engineers should seek to minimize tensile stresses through proper design and use of support tooling so as to permit use of the highest performance die steels on crucial components. When required tooling designs must involve significant tensile stresses, then selection of a tougher tool steel with reduced wear resistance, most likely one of the shock resisting grades, is advised.

Common Errors in Tool Design

  • Use of sharp corners.
  • Failure to use fillets or adequate radii.
  • Presence of non-uniform sections in tooling causing variation in stress distribution in service as well as variable quenching rates during hardening.
  • Use of improper clearance between punch and die edges.
  • Tool designs involving excessive unit stresses or overloading during operation. Tools should be redesigned to operate at a lower unit stress.

Sensitive Tooling Designs

If sharp corners and variable sections cannot be avoided in the design of a part the use of an air hardening die steel is essential for greatest safety in hardening. Cracking and/or distortion are more apt to occur on such sensitive sections when liquid quenching is employed during hardening.

Proper Tool Clearance

Tool clearance is the distance between adjacent punch and die edges. In general the press load required for a given operation decreases as clearance increases, so tools are more highly stressed with a small degree of punch and die clearance. Enlarging clearance from 5 to 10% of stock thickness usually will improve tool life. Although the finish of the sheared edges of parts may improve with small clearance, tool life will be shortened. Breakage due to misalignment may also result.

While acceptable clearance is often 10% of the stock thickness, this subject is debatable since many variables besides stock thickness influence clearance, including stock material, hardness and surface (scale condition and finish) and the required finish on the shear cut.

Data is typical and should not be construed as actual values for any catagory.
Applications and technical information require engineers and tool designers to exercise independent judgement.